Summer is an ideal time to take a hike, especially if you have the opportunity to explore one of our country’s many state and national parks. But if you venture far from home, it’s essential to make sure you’re prepared for the local climate and other conditions you may encounter on the trail, especially if you’re not an experienced hiker. Higher temperatures than you’re accustomed to or other extreme weather can be deadly.

“If you’re taking a hike in mid-July in the Arizona desert, there’s a very different list of considerations than if you’re in the mountains of Montana or the forests of North Carolina,” says Dr. N. Stuart Harris, chief of the Division of Wilderness Medicine at Harvard-affiliated Massachusetts General Hospital. Here’s a run-down of what to consider before you hit the trail.

Traveling companions, safety notifications, and orientation

First, it’s safer to travel in pairs or a group of people. But always tell someone not on your hike where you’re going, your anticipated route, and when you expect to return. National parks often require reservations or permits for overnight stays or treks to certain locales, and keep a record of day-hikers, so sign up as requested. If you end up getting injured or lost, the information can make a huge difference in locating you more quickly.

Remember to bring a map and know how to orient yourself. In many wilderness areas, cell service may be spotty or nonexistent, so don’t count on using your phone’s GPS.

In the desert, you may be able to see for 50 miles in the distance. But if you’re in a steep, wooded area, you might not be able to see 100 yards ahead and it’s much easier to become disoriented, says Dr. Harris.

Be ready for heat, humidity, and other weather hazards

Check forecasts first. Always check the forecast so you can be prepared for weather changes. Temperatures may drop and wind may increase as you climb higher. If you’re in an area prone to thunderstorms, lightning injury should definitely be on your radar, says Dr. Harris. Learn these lightning safety tips from the Centers for Disease Control and Prevention. Because these storms usually strike in the afternoon, you can minimize your risk by hiking in the earlier part of the day.

Hydrate well. During any type of exercise — especially hiking, which often demands a fair bit of exertion — be sure to drink extra water to replace the fluid you lose from sweating. On a warm day, you might not notice you’re sweating if it’s breezy. Pay attention to any signs or alerts advising hikers on how much water is best to carry.

Consider humidity. Temperature isn’t the only consideration, however. “If you’re in Arizona and the temperature is over 100° F, your body may be better able to release heat by sweating than if you’re in a very humid area,” says Dr. Harris. In the Great Smoky Mountains, for example, the temperature in July may be only in the high 80s. But humidity levels usually hover around 75% or higher. That means your sweat will evaporate more slowly, so your body’s natural cooling mechanism doesn’t work as efficiently. Be sure to rest and hydrate if you start feeling overheated.

What to wear and bring

Many park websites offer detailed safety tips specific to the terrain and weather you may encounter on a hike, so check before you go. Five basics to consider are as follows:

• If your hike involves rocky or uneven terrain, hiking boots will offer more support than tennis shoes.
• You’ll be more comfortable in lightweight, moisture-wicking clothing, but bring extra layers and rain gear, if the weather forecast suggests this is appropriate. Temperature drops can be surprising in some places when the sun wanes, so be prepared to layer up as needed if you’re out longer than expected.
• Wear a wide-brimmed hat and sunglasses to shield you from the sun’s glare — and don’t forget to apply sunscreen to all exposed skin before you set off.
• Along with plenty of fluids, bring high-energy snacks. If you get off course or encounter a problem, you’ll be glad you did.

Additionally, depending on where you’re hiking, you may need to dodge rash-inducing plants, including stinging nettles, poison oak, or poison ivy. Bring insect repellent to fend off biting insects and follow prevention strategies for ticks, which may harbor bacteria responsible for Lyme disease and other illnesses. Finally, carry a first aid kit with bandages for cuts and scrapes and moleskin for blisters.

About the Author

Julie Corliss, Executive Editor, Harvard Heart Letter

Julie Corliss is the executive editor of the Harvard Heart Letter. Before working at Harvard, she was a medical writer and editor at HealthNews, a consumer newsletter affiliated with The New England Journal of Medicine. She … See Full Bio View all posts by Julie Corliss

About the Reviewer

Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing

Dr. Howard LeWine is a practicing internist at Brigham and Women’s Hospital in Boston, Chief Medical Editor at Harvard Health Publishing, and editor in chief of Harvard Men’s Health Watch. See Full Bio View all posts by Howard E. LeWine, MD

When you live in a coastal area, preparing early for potential hurricanes is a must. Storms can develop quickly, leaving little time to figure out where you’ll be safe or which items to pack if you have to evacuate. And health care necessities, such as medications or medical equipment, are often overlooked in the scramble.

“People might bring their diabetes medication but forget their blood sugar monitor, or bring their hearing aids but forget extra batteries for them,” says Dr. Scott Goldberg, medical director of emergency preparedness at Brigham and Women’s Hospital and a longtime member of a FEMA task force that responds to hurricane-damaged areas.

Here’s some insight on what to expect this hurricane season, and how to prioritize health care in your hurricane kit.

What will the 2024 hurricane season look like?

This year’s hurricane predictions underscore the urgency to start preparations now.

Forecasters with the National Oceanic and Atmospheric Administration’s National Weather Service expect above-normal activity for the 2024 hurricane season (which lasts until November 30).

Meteorologists anticipate 17 to 25 storms with winds of 39 mph or higher, including eight to 13 hurricanes — four to seven of which could be major hurricanes with 111 mph winds or higher.

What kinds of plans should you make?

Preparing for the possibility of big storms is a major undertaking. Long before ferocious winds and torrential rains arrive, you must gather hurricane supplies, figure out how to secure your home, and determine where to go if you need to evacuate (especially if you live in a flood zone). Contact the emergency management department at your city or county for shelter information.

If you’ll need help evacuating due to a medical condition, or if you’ll need medical assistance at a shelter, find out if your county or city has a special needs registry like this one in Florida. Signing up will enable first responders to notify you about storms and transport you to a special shelter that has medical staff, hospital cots, and possibly oxygen tanks.

What should you pack?

While a shelter provides a safe place to ride out a storm, including bathrooms, water, and basic meals, it’s up to you to bring everything else. It’s essential to pack medical equipment and sufficient medications and health supplies.

“It’s natural to just grab the prescription medications in your medicine cabinet, but what if it’s only a two-day supply? It might be a while before you can get a refill. We recommend at least a 14-day or 30-day supply of every prescription,” Dr. Goldberg says. “Talk to your doctor about the possibility of getting an extra refill to keep on standby for your go bag.”

Other health-related items you’ll want to pack include:

• medical supplies you use regularly, such as a blood pressure monitor, heart monitor, CPAP machine, wheelchair, or walker
• over-the-counter medicines you use regularly, such as heartburn medicine or pain relievers
• foods for specific dietary needs, such as gluten-free food if you have celiac disease (if you have infants or children, you’ll need to bring foods they can eat)
• healthy, nonperishable snacks such as nuts, nut butters, trail mix, dried fruit, granola bars, protein bars, and whole-grain bread, crackers, or cereals
• hygiene products such as soap, hand sanitizer, toothbrushes and toothpaste, shampoo, deodorant, infant or adult diapers, lip balm, moist towelettes, and toilet paper — because shelters often run out of it.

Remember the basics

In some ways, you can think of shelter living like camping. You’ll need lots of basic supplies to get through it, including:

• a sleeping bag or blanket and pillow for each person in your family
• clean towels and washcloths
• a few extra changes of clothes per person
• a first-aid kit
• flashlights and extra batteries
• chargers for your electronic gadgets
• rechargeable battery packs.

Bring important paperwork

In addition to supplies, bring important documents such as:

• a list of your medications, vitamins, and supplements (include the name, dose, and frequency of each one)
• a list of the names, addresses, and phone numbers of your primary care provider and any specialists who treat you
• a list of your emergency contacts and their phone numbers
• your pharmacy’s phone number and address
• copies of your birth certificate and driver’s license
• copies of home, car, or life insurance policies
• copies of your health insurance cards
• a copy of your advance directive — which includes your living will and health care proxy form.

“Store these documents on a flash drive. Also make photocopies of them, which are easiest for doctors to consult in an emergency setting. Place them in a plastic zip-top bag to keep them dry,” Dr. Goldberg advises.

Prepare right now

Start today. Gather as many go-bag supplies as you can, including the bags. A small suitcase, backpack, or duffel bag for each person in your family will work well.

And try not to put off these important preparations. “Hurricanes are major stressors. You might be worried, sleep deprived, fatigued, and emotional,” Dr. Goldberg says. “All of that will make it hard to think clearly. You’ll do yourself and your family a favor by having discussions now and getting started on your hurricane plan.”

About the Author

Heidi Godman, Executive Editor, Harvard Health Letter

Heidi Godman is the executive editor of the Harvard Health Letter. Before coming to the Health Letter, she was an award-winning television news anchor and medical reporter for 25 years. Heidi was named a journalism fellow … See Full Bio View all posts by Heidi Godman

About the Reviewer

Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing

Dr. Howard LeWine is a practicing internist at Brigham and Women’s Hospital in Boston, Chief Medical Editor at Harvard Health Publishing, and editor in chief of Harvard Men’s Health Watch. See Full Bio View all posts by Howard E. LeWine, MD

Trees enhance life in a multitude of ways. They combat climate change by reducing greenhouse gases in the atmosphere. They muffle sound pollution and reduce air pollution, drawing in carbon dioxide and releasing oxygen. When rain pours from the skies, trees decrease stormwater runoff, preventing flooding and soil erosion. They also provide valuable habitats to support biodiversity in insects, birds, and other animals, and microorganisms. The list goes on.

Equally important is accumulating evidence that simply spending time around trees and green spaces uplifts our health and mood. Below are a few of the biggest benefits we reap.

Keeping it cool: Trees help prevent heat-related illness

Climate change is causing rising temperatures and more heat waves across the US. These effects are worse for those who live in neighborhoods known as urban heat islands, where asphalt and concrete soak up heat during the day and continue to radiate it at night. Temperatures can reach 7° F hotter than suburban, rural, or simply wealthier and leafier neighborhoods.

Trees and their leafy canopy provide shade that helps to prevent urban heat islands. What does that mean for individuals? It translates to fewer heat-related health illnesses, which strike outdoor workers and younger, older, and medically vulnerable people more often. A study published in The Lancet calculated that increasing tree canopy to 30% coverage in 93 European cities could prevent an estimated four in 10 premature heat-related deaths in adults in those cities.

How trees help children: Better mood, behavior, attention, and more

Spending more time in nature has been linked with better health outcomes like lower blood pressure, better sleep, and improvement in many chronic conditions in adults. These findings are prompting a growing interest in forest therapy, a guided outdoor healing practice that leads to overall improved well-being. But what’s also remarkable are the varied benefits of trees and nature for children.

One study of children 4 to 6 years old found that those who lived close to green space demonstrated less hyperactive behavior and scored more highly on attention and visual memory testing measures compared with children who did not.

Just seeing trees can have mental health benefits. In Michigan, a study of children between the ages of 7 and 9 demonstrated that students who could see trees from their school windows had fewer behavioral problems than those with limited views.

In Finland, researchers modified daycare outdoor playscape environments to mimic the forest undergrowth. These daycares were compared to control standard daycares and nature-oriented daycares where children made daily visits to nearby forests. At the end of 28 days, the children in the daycares with modified forest undergrowth playscapes harbored a healthier microbiome and had improved markers of their immune systems as compared to their counterparts.

How green space helps communities

Having green space in neighborhoods also does a lot to enrich the well-being of communities. A randomized trial in a US city planted and maintained grass and trees in previously vacant lots. Researchers then compared these green spaces to lots that were left alone.

In neighborhoods below the poverty line, there was a reduction in crime for areas with greened lots compared to untouched vacant lots. Meanwhile, residents who lived near lots that were greened reported feeling safer and increased their use of the outside space for relaxing and socializing.

How can you help?

Unfortunately, urban tree canopy cover has been declining over the years. To counter this decline, many towns and nonprofit organizations have programs that provide trees for planting.

A few examples in Massachusetts are Canopy Crew in Cambridge and Speak for the Trees in Boston. (Speak for the Trees also offers helpful information on selecting and caring for trees). Neighborhood Forest provides trees for schools and other youth organizations across the US. Look for a program near you!

Planting trees native to your region will better suit the local conditions, wildlife, and ecosystem. Contact your regional Native Plant Society for more information and guidance. If you are worried about seasonal allergies from tree pollen, many tree organizations or certified arborists can give you guidance on the best native tree selections.

If planting trees is not for you but you are interested in contributing to the mission, consider donating to organizations that support reforestation, like The Canopy Project and the Arbor Day Foundation.

About the Author

Wynne Armand, MD, Contributor

Dr. Wynne Armand is a physician at Massachusetts General Hospital (MGH), where she provides primary care; an assistant professor in medicine at Harvard Medical School; and associate director of the MGH Center for the Environment and … See Full Bio View all posts by Wynne Armand, MD

Ever wonder if every medical test or treatment you've taken was truly necessary? Or are you inclined to get every bit of health care you can? Maybe you feel good about getting the most out of your health insurance. Perhaps a neighborhood imaging center is advertising discounted screening tests, your employer offers health screens as a perk, or you're intrigued by ads touting supplements for a seemingly endless number of conditions.

But keep in mind: just because you could get a particular test or treatment or take a supplement doesn't mean you should. One study suggests that as much as 20% of all health care in the US is unneeded. In short: when it comes to health care, more is not always better.

Isn't it better to be proactive about your health?

We're all taught that knowledge is power. So it might seem reasonable to want to know as much as possible about how your body is working. And isn't it better to take action before there's a problem rather than waiting for one to develop? What's the harm of erring on the side of more rather than less?

The truth is that knowledge is not always power: if the information is irrelevant to your specific situation, redundant, or inaccurate, the knowledge gained through unnecessary health care can be unhelpful or even harmful. Unnecessary tests, treatments, and supplements come with risks, even when they seem harmless. And, of course, unnecessary care is not free — even if you're not paying a cent out of pocket, it drives up costs across health systems.

Screening tests, wellness strategies, and treatments to reconsider

Recommended screening tests, treatments, and supplements can be essential to good health. But when risks of harm outweigh benefits — or if proof of any benefit is lacking — think twice. Save your time, money, and effort for health care that is focused on the most important health threats and backed by evidence.

Cancer screening: When to stop?

Screening tests for some cancers are routinely recommended and can be lifesaving. But there's a reason they come with a recommended stop age. For instance, guidelines recommend that a person at average risk of colorectal cancer with previously normal colonoscopies stop having them once they turn 75. Similar limits apply to Pap smears (age 65) and mammograms (age 75). Studies suggest that beyond those ages, there is little benefit to continuing these screens.

Watch out for wellness marketing

Dietary supplements are a multibillion-dollar industry. And a whopping 70% or more of US adults take at least one, such as vitamin D, fish oil, or a multivitamin. People often consider them as insurance in case vital elements are missing from their diet, or they believe supplements can prevent dementia, heart disease, or another condition.

Yet little evidence supports a benefit of routine supplement use for everyone. While recent studies suggest a daily multivitamin might slow cognitive decline in older adults, there's no medical consensus that everyone should be taking a multivitamin. Fish oil (omega-3) supplements haven't proven to be as healthful as simply eating servings of fatty fish and other seafood low in toxic chemicals like mercury and PCBs. And the benefits of routinely taking vitamin D supplements remain unproven as well.

It's worth emphasizing that dietary supplements clearly provide significant benefit for some people, and may be recommended by your doctor accordingly. For example, if you have a vitamin or mineral deficiency or a condition like age-related macular degeneration, good evidence supports taking specific supplements.

Reconsider daily aspirin

Who should be taking low-dose aspirin regularly? Recommendations have changed in recent years, so this is worth revisiting with your health care team.

• Older recommendations favored daily low-dose aspirin to help prevent cardiovascular disease, including first instances of heart attack and stroke.
• New recommendations favor low-dose aspirin for people who've already experienced a heart attack, stroke, or other cardiovascular disease. Adults ages 40 to 59 who are at a high risk for these conditions and low risk for bleeding also may consider it.

Yet according to a recent study, nearly one-third of adults 60 and older without past cardiovascular disease take aspirin, despite evidence that it provides little benefit for those at average or low risk. Aspirin can cause stomach bleeding and raise risk for a certain type of stroke.

Weigh in on prostate cancer screening

Men hear about prostate cancer often. It's common, and the second leading cause of cancer deaths among men. But PSA blood tests and rectal exams to identify evidence of cancer in the prostate are no longer routinely recommended for men ages 55 to 69 by the United States Preventative Services Task Force.

The reason? Studies suggest that performing these tests does not reliably reduce suffering or prolong life. Nor do possible benefits offset downsides like false positives (test results that are abnormal despite the absence of cancer). That can lead to additional testing, some of which is invasive.

Current guidelines suggest making a shared decision with your doctor about whether to have PSA testing after reviewing the pros and cons. For men over age 70, no screening is recommended. Despite this, millions of men have PSA tests and rectal examinations routinely.

Not everyone needs heart tests

There are now more ways than ever to evaluate the health of your heart. But none are routinely recommended if you're at low risk and have no signs or symptoms of cardiovascular disease. That's right: in the absence of symptoms or a high risk of cardiovascular disease, it's generally safe to skip EKGs, stress tests, and other cardiac tests.

Yet many people have these tests as part of their routine care. Why is this a problem? Having these tests without a compelling reason comes with risks, especially false positive results that can lead to invasive testing and unneeded treatment.

Four more reasons to avoid unnecessary care

Besides the concerns mentioned already, there are other reasons to avoid unnecessary care, including:

• The discomfort or complications of testing. If you're needle-phobic, getting a blood test is a big deal. And while complications of noninvasive testing are rare (such as a skin infection from a blood test), they can occur.
• The anxiety associated with waiting to find out test results
• False reassurance that comes with false negatives (results that are normal or nearly so, suggesting no disease when disease is actually present)
• All treatments have side effects. Even minor reactions — like occasional nausea or constipation — seem unacceptable if there's no reason to expect benefit from treatment.

The bottom line

You may believe your doctor wants you to continue with your current schedule of tests and treatments, while they might think this is your preference! It's worth discussing if you haven't already, especially if you suspect you may be taking pills or getting tests you don't truly need.

If your doctor says you can safely skip certain tests, treatments, and supplements, it doesn't mean that he or she is neglecting your health or that you don't deserve great health care! It's likely that the balance of risks and benefits simply doesn't support doing these things.

Less unnecessary care could free up resources for those who need it most. And it could save you time, money, and unnecessary risks or side effects, thus improving your health. It's a good example of how less can truly be more.

About the Author

Robert H. Shmerling, MD, Senior Faculty Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing

Dr. Robert H. Shmerling is the former clinical chief of the division of rheumatology at Beth Israel Deaconess Medical Center (BIDMC), and is a current member of the corresponding faculty in medicine at Harvard Medical School. … See Full Bio View all posts by Robert H. Shmerling, MD

Cancer treatment can involve difficult tradeoffs, and that's also true of the testosterone-blocking drugs used in treating prostate cancer. These drugs work in two different ways. Androgen deprivation therapies (ADT) shut down the body's production of testosterone, a hormone that fuels prostate cancer growth. A newer class of drugs called androgen-receptor signaling inhibitors (ARSIs) block testosterone by deflecting the hormone from its cell receptor.

ADT can slow or control prostate cancer, and mounting evidence shows that adding ARSIs also improves survival when the disease is in advanced stages. This treatment combination is called intensified ADT. Researchers are now testing intensified ADT for some men with early-stage prostate cancer as well.

However, all drugs that block testosterone have challenging side effects, including metabolic changes that can compromise cardiovascular health. In June, British researchers reported that cardiovascular risks worsen when ADT and ARSIs are given together. The authors concluded that men who get intensified ADT should be counseled about the risks, and monitored for signs of heart disease before and after the treatment begins.

Study goals and results

The findings were derived from a systematic review of 24 clinical trials that assessed ADT and ARSI treatment for prostate cancer. Published between 2012 and 2024, the trials enrolled a combined total of 22,166 men ages 63 to 77. Their diagnoses ranged across the prostate cancer spectrum, from nonmetastatic cancer with aggressive features to metastatic prostate cancer that no longer responded to ADT by itself.

The goal of the systematic review was to compare ADT and intensified ADT with respect to cardiac events, including hypertension, cardiac arrhythmias (abnormal heartbeats), blood clots, or — in the worst case — heart attack or stroke.

Results showed that adding an ARSI to ADT approximately doubles the risk of a cardiac event across all prostate cancer states. Risks for severe "grade 3" events that can require hospitalization ranged between 7.8% and 15.6%. Notably, giving two ARSIs — abiraterone acetate and enzalutamide — led to a roughly fourfold increase in cardiac risk. Mounting evidence shows that combining abiraterone acetate and enzalutamide worsens side effects without improving prostate cancer survival. The use of that combination is now broadly discouraged by expert groups around the world.

The authors emphasize that intensified therapy is riskier for men with pre-existing cardiac conditions than it is for healthier men. In an accompanying editorial, Dr. Katelyn Atkins, a radiation oncologist at Cedars-Sinai Medical Center in Los Angeles, noted that cardiovascular disease is the second leading cause of death among men with prostate cancer.

Candidates for traditional or intensified ADT, Dr. Atkins wrote, should be assessed for atherosclerosis, fatty plaques in coronary arteries that can accumulate asymptomatically. Fortunately, cardiac risk factors are treatable by lowering blood pressure, eating a heart-healthy diet, exercising, and in some cases using a cholesterol-lowering drug called a statin.

Experts comment

"More and more research shows that intensive therapy prolongs survival, and may in some men even evoke a cure," said Dr. David Crawford, head of urologic oncology at the University of Colorado Anschutz Medical Campus who was not involved in the study. "We have learned time and again from the treatment of many cancers that it is not one drug followed by another and another that results in the best outcomes. Rather, it is combining drugs more effectively to treat the cancer.

"Still, we need to tackle the challenges of prostate cancer treatment and focus on preventing cardiovascular events and other side effects of ADT. As clinicians and in clinical studies, we have seen that men who maintain their weight, exercise, expand muscle mass, and maintain normal lipids and blood pressure do much better than men who gain weight and have a lot of cardiovascular risk factors."

"This important study re-emphasizes the necessity to keep a patient’s cardiovascular history front and center when treatment choices are made, " said Dr. Marc Garnick, the Gorman Brothers Professor of Medicine at Harvard Medical School and Beth Israel Deaconess Medical Center, and editor-in-chief of the Harvard Medical School Guide to Prostate Diseases.

"Intensification of treatment — that is, adding several drugs earlier and earlier in prostate cancer management — is to be both encouraged and cautioned. The caution is for physicians to consider and discuss pre-existing risk factors and how to modify them when deciding upon treatment programs. The ARSI class of drugs have greatly improved outcomes. The goal is to maximize the best outcomes while minimizing the side effects."

About the Author

Charlie Schmidt, Editor, Harvard Medical School Annual Report on Prostate Diseases

Charlie Schmidt is an award-winning freelance science writer based in Portland, Maine. In addition to writing for Harvard Health Publishing, Charlie has written for Science magazine, the Journal of the National Cancer Institute, Environmental Health Perspectives, … See Full Bio View all posts by Charlie Schmidt

About the Reviewer

Marc B. Garnick, MD, Editor in Chief, Harvard Medical School Annual Report on Prostate Diseases; Editorial Advisory Board Member, Harvard Health Publishing

Dr. Marc B. Garnick is an internationally renowned expert in medical oncology and urologic cancer. A clinical professor of medicine at Harvard Medical School, he also maintains an active clinical practice at Beth Israel Deaconess Medical … See Full Bio View all posts by Marc B. Garnick, MD

Months after actor and comedian Robin Williams took his own life in August 2014, autopsy results revealed he had a devastating disease: Lewy body dementia (LBD). Unlike Alzheimer’s disease and even frontotemporal dementia, this brain disorder has tended to hide in the shadows. But work is underway to change that, says Dr. Stephen Gomperts, an assistant professor of neurology at Harvard Medical School and director of the Lewy Body Dementia Unit at Harvard-affiliated Massachusetts General Hospital.

Perhaps surprisingly, LBD is the second most common cause of neurodegenerative dementia after Alzheimer’s disease. How do its symptoms differ? Who is at risk? And how is it diagnosed and treated?

What is Lewy body dementia?

First, it’s important to know that there are two main types of this dementia. One is called dementia with Lewy bodies, or DLB. A second type, known as Parkinson’s disease dementia, or PDD, may arise late in the course of that illness.

These disorders stem from an abnormal buildup of protein deposits in the brain called Lewy bodies. The deposits, formed from a protein called alpha-synuclein, settle in brain areas affecting thinking, behavior, perception, and movement.

Much like Alzheimer’s disease, LBD is progressive and ultimately fatal. But while the median lifespan of people who have this illness is seven years, there is a high degree of variation in the duration of disease, says Dr. Gomperts. “Many people respond well to medicines that aim to improve their ability to function and quality of life.”

How common is it?

More than a million Americans live with Lewy body dementia. Others who likely have the disease may not have sought care or have been misdiagnosed, Dr. Gomperts says. “In the past, LBD was often subsumed under the general umbrella of ‘dementia’ or ‘Alzheimer’s.’ It’s still significantly underdiagnosed, but that’s getting better.”

Most people with LBD develop symptoms after age 50, so the numbers are likely to grow as the population continues to age.

How is Lewy body dementia similar to Alzheimer’s disease?

As with Alzheimer’s, LBD affects a person’s ability to think clearly, remember details, solve problems, focus on tasks, and eventually to care for themselves. “Gradually progressive trouble with thinking is the key shared feature between the two. This initially doesn’t impact activities of daily living, but ultimately it does,” he explains.

How does Lewy body dementia differ from Alzheimer’s disease?

In Alzheimer’s disease, memory problems usually occur early and are the dominant problem. In contrast, in LBD, difficulties with problem-solving or spatial problems tend to arise before memory difficulties. But any of these symptoms can occur first or in combination, and they may fluctuate. Perception is often affected, which can manifest as visual hallucinations. Delusions (false beliefs) are also common as the disease progresses.

“Whereas hallucinations and delusions are common late in the course of Alzheimer’s disease, visual hallucinations often arise early in LBD. For example, a person with LBD might see people or animals that aren’t there,” he says. “Such hallucinations are only rarely perceived as threatening.”

Other differences are:

• Acting out dreams. People with LBD may act out their dreams. Known as REM sleep behavioral disorder, this problem often arises even before thinking problems start.
• Changes in movement. People with Lewy body dementia often move slowly and stiffly, developing tremors and gait changes and becoming prone to falls. When people have PDD, progressive movement problems arise early and are the rule. This symptom leads to the initial diagnosis of Parkinson’s disease. In DLB, movement is often but not always affected.

How do experts distinguish between PDD and DLB?

It’s all in the timing of key symptoms. A “one-year rule” distinguishes each disorder.

• PDD: When someone diagnosed with Parkinson’s develops memory and thinking problems that impair activities of daily living more than a year after their movement problems arise, PDD is diagnosed.
• DLB: When cognitive problems arise earlier, or come without movement problems, dementia with Lewy bodies is diagnosed.

“But this one-year rule is somewhat arbitrary,” Dr. Gomperts says. “Increasingly we think of this as a spectrum of disease.”

Who is at risk for Lewy body dementia?

Age is considered the biggest risk factor for the disease. Most cases have no known trigger, although a handful of gene mutations can predispose someone to LBD.

Several lifestyle factors such as diet, lack of exercise, and toxic exposures have been linked to Parkinson’s disease risk. However, little research has been done to examine whether these factors are linked to LBD. People who have suffered head trauma appear to develop LBD and Parkinson’s more often. Both conditions also disproportionately affect men. “We think that’s telling us something important, but it’s not yet clear what,” Dr. Gomperts says.

How is Lewy body dementia diagnosed?

The diagnosis of DLB is made when key clinical features are present — trouble thinking, fluctuations in thinking, movement problems, and REM sleep behavioral disorder — in the absence of other causes. The diagnosis of PDD is made when dementia arises in Parkinson’s disease.

Diagnosing DLB is challenging because early symptoms are often confused with symptoms that arise in other brain or psychiatric disorders. Many people don’t receive an accurate diagnosis until their symptoms become more advanced, Dr. Gomperts says.

An array of tests and imaging exams is deployed to tease out LBD from other conditions that can trigger similar symptoms, such as Alzheimer’s disease, vascular disease, thyroid disorders, or vitamin B12 deficiency.

“Not all cases are clear-cut and not all physicians are skilled at making the diagnosis,” he says. “Accuracy is also lower in early disease.”

Are there treatments for Lewy body dementia?

Yes. Although there’s no cure, treatments like medications, physical therapy, and counseling can help with specific symptoms of LBD, such as thinking problems, hallucinations, and sleep disturbances. LBD-related movement symptoms can also be treated with some medications used for Parkinson’s. This makes it easier to walk and do other activities.

“We’ve also learned that several medications can cause or worsen certain symptoms, such as confusion, delusions, hallucinations, and movement problems,” Dr. Gomperts says. “In fact, some medications that target hallucinations and delusions often worsen motor function and can even be fatal in LBD. They need to be avoided.”

About the Author

Maureen Salamon, Executive Editor, Harvard Women's Health Watch

Maureen Salamon is executive editor of Harvard Women’s Health Watch. She began her career as a newspaper reporter and later covered health and medicine for a wide variety of websites, magazines, and hospitals. Her work has … See Full Bio View all posts by Maureen Salamon

About the Reviewer

Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing

Dr. Howard LeWine is a practicing internist at Brigham and Women’s Hospital in Boston, Chief Medical Editor at Harvard Health Publishing, and editor in chief of Harvard Men’s Health Watch. See Full Bio View all posts by Howard E. LeWine, MD

Each year, more than 4.5 million dog bites occur in the United States. Despite what you might assume, most of these incidents don’t happen when an unfamiliar dog attacks someone in a park or another outdoor location. Instead, most dog bites are inflicted by a pet dog in a home.

Here’s advice for avoiding these upsetting and potentially serious injuries — and the steps you should take if you sustain a dog bite.

Why do dog bites happen?

Some dog bites happen by accident when people wrestle or play tug-of-war with their dog. But most of the time, dogs bite people as a reaction to feeling stressed, threatened, scared, or startled, according to the American Veterinary Medical Association (AVMA). More than half of dog bites occur in children, and they’re far more likely to be seriously injured than adults.

“People don’t always heed the behavioral signals that a dog is uncomfortable,” says Dr. Christopher Baugh, associate professor of emergency medicine at Harvard Medical School. For example, some dogs are highly territorial and will bark, growl, snap, and lunge if outsiders enter their space — whether that’s an apartment, yard, or crate. Or dogs may exhibit resource guarding, which shows up as anxious, aggressive behavior around food, toys, or beds.

“These situations can be high-risk, and children in particular have less awareness of that risk,” says Dr. Baugh, who has children and two mixed-breed rescue dogs, Harley and Roxi.

What can you do to prevent dog bites?

Any dog — even a sweet, cuddly dog — can bite if provoked, according to the AVMA. Never leave young children alone with a dog without adult supervision. And teach children to never disturb a dog while it’s eating, sleeping, or caring for puppies.

In a study of 321 facial dog bites treated at Harvard-affiliated Massachusetts General Hospital over a 20-year period, 88% of the bites were from known dogs. Most were in adults and occurred after playing with the dog, feeding the dog, and placing their face close to the dog. However, the hand (usually a person’s dominant hand) is probably the most common location for a dog bite in an adult, says Dr. Baugh.

Other tips from the CDC to prevent dog bites include the following:

• Always ask a dog’s owner if it’s okay to pet their dog, even if the dog appears friendly.
• Make sure the dog sees and sniffs you before reaching out to pet it.
• Don’t pet a dog that seems to be hiding, scared, sick, or angry.

What if an unfamiliar dog approaches you? Remain calm and still, avoiding eye contact with the dog. Stand with the side of your body facing the dog and say “no” or “go home” in firm, deep voice. Wait for the dog to retreat or move yourself slowly away.

What should you do if you’re bitten by a dog?

Clean the wound with mild soap and running water, then cover it with a clean bandage or cloth. Some online resources recommend applying an antibiotic ointment or cream. But these products are recommended only for people with clear evidence of an infection, such as redness, pus, pain, swelling, or warmth, according to the American Academy of Dermatology.

If the injury is serious — with a bite on the face, heavy bleeding, or a possible broken bone — go to the emergency room. That’s also a good idea if you’re bitten by an unknown or stray dog, in the rare event that you might need medicines to prevent rabies (rabies post-exposure prophylaxis).

“Often, people are shocked after being bit and will understandably focus all their attention on their wound,” says Dr. Baugh. The dog’s owner may check in to see if you’re okay, but then walk away. But you should get the person’s contact information and make sure the dog is vaccinated against rabies, he says.

Keep in mind that:

• Emergency rooms are often crowded with long waits, so an urgent care clinic is a good option if the injury doesn’t require immediate attention.
• Some wounds require stitches, ideally within 12 to 24 hours.
• The doctor may prescribe antibiotics to prevent possible infections, especially if you have health problems such as a weakened immune system or diabetes.
• You may also need a tetanus booster if you haven’t had one in the past 10 years. If your vaccine history isn’t available or you can’t remember, you’ll get a tetanus booster just in case.

What if a dog bite is less serious?

Let’s say you have a less serious bite from a family dog known to have a current rabies vaccine. Bites that don’t require stitches can be cleaned with mild soap and running water, then evaluated by your regular health care provider. They may tell you to simply monitor the wound for signs of infection.

“Doctors are trying to be more thoughtful about prescribing antibiotics and limit their use in low-risk situations, because overuse contributes to antibiotic resistance and exposes people to potential side effects without any benefit,” says Dr. Baugh.

About the Author

Julie Corliss, Executive Editor, Harvard Heart Letter

Julie Corliss is the executive editor of the Harvard Heart Letter. Before working at Harvard, she was a medical writer and editor at HealthNews, a consumer newsletter affiliated with The New England Journal of Medicine. She … See Full Bio View all posts by Julie Corliss

About the Reviewer

Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing

Dr. Howard LeWine is a practicing internist at Brigham and Women’s Hospital in Boston, Chief Medical Editor at Harvard Health Publishing, and editor in chief of Harvard Men’s Health Watch. See Full Bio View all posts by Howard E. LeWine, MD

Animals renowned for their outstanding night vision include owls, cats, tarsiers (a tiny primate in Southeast Asia) — and even the dung beetle.

But humans? Not so much.

Over time, many people suffer from night blindness, also known as nyctalopia. This condition makes seeing in dim or dark settings difficult because your eyes cannot adjust to changes in brightness or detect light.

What are the dangers for those experiencing night blindness?

Night blindness is especially problematic and dangerous when driving. Your eyes cannot adjust between darkness and the headlights of oncoming vehicles, other cars may appear out of focus, and your depth perception becomes impaired, which makes it difficult to judge distances.

Night blindness also may affect your sight at home by making it hard for your vision to quickly adjust to a dark room after turning off the lights. “This can cause people to bump into furniture or trip and suffer an injury,” says Dr. Isabel Deakins, an optometrist with Harvard-affiliated Massachusetts Eye and Ear.

What happens in the eye to create night blindness?

The ability to see in low-light conditions involves two structures in the eye: the retina and the iris.

The retina, located in the back of the eye, contains two types of light-detecting cells called cones and rods. The cones handle color vision and fine details while the rods manage vision in dim light.

The iris is the colored part of your eye. It contains muscles that widen or narrow the opening of your pupil to adjust how much light can enter your eyes.

If your irises don’t properly react, the pupils can dilate and let in too much light, which causes light sensitivity and makes it hard to see in bright light. Or your pupils may remain too small and not allow in enough light, making it tough to see in low light.

What causes night blindness?

Night blindness is not a disease but a symptom of other conditions. “It’s like having a bruise on your body. Something else causes it,” says Dr. Deakins.

Several conditions can cause night blindness. For instance, medications, such as antidepressants, antihistamines, and antipsychotics, can affect pupil size and how much light enters the eye.

Eye conditions that can cause night blindness include:

• glaucoma, a disease that damages the eye’s optic nerves and blood vessels
• cataracts, cloudy areas in the lens that distort or block the passage of light through the lens
• dry eye syndrome.

However, one issue that raises the risk of night blindness that you can’t control is age. “Our eyes react more slowly to light changes as we age, and vision naturally declines over time,” says Dr. Deakins.  “The number of rods in our eyes diminish, pupils get smaller, and the muscles of the irises weaken.”

What helps if you have night blindness?

If you notice any signs of night blindness, avoid driving and get checked by an eye care specialist like an optometrist or ophthalmologist. An eye exam can determine if your eyeglass prescription needs to be updated.

“Often, a prescription change is enough to reduce glare when driving at night," says Dr. Deakins. “You may even need separate glasses with a stronger eye prescription that you wear only when driving at night.”

Adding an anti-reflective coating to your lens may help to cut down on the glare of the headlights of an oncoming car. However, skip the over-the-counter polarized driving glasses sold at many drug stores. "These may help cut down on glare, but they don't address the causes of night blindness," says Dr. Deakins.

An eye exam also will identify glaucoma or cataracts, which can be treated. Glaucoma treatments include eyedrops, laser treatment, or surgery. Cataracts are corrected with surgery to replace the clouded lens with an artificial one. Your eye care specialist can also help identify dry eye and recommend treatment.

Ask your primary care clinician or a pharmacist if any medications that you take may cause night blindness. If so, it may be possible to adjust the dose or switch to another drug.

Three more ways to make night driving safer

You also can take steps to make night driving safer. For example:

• Wash the lenses of your glasses regularly. And take them to an optician to buff out minor scratches.
• Keep both sides of your front and rear car windshields clean so that you can see as clearly as possible.
• Dim your dashboard lights, which cause glare, and use the night setting on your rearview mirror.

About the Author

Matthew Solan, Executive Editor, Harvard Men's Health Watch

Matthew Solan is the executive editor of Harvard Men’s Health Watch. He previously served as executive editor for UCLA Health’s Healthy Years and as a contributor to Duke Medicine’s Health News and Weill Cornell Medical College’s … See Full Bio View all posts by Matthew Solan

About the Reviewer

Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing

Dr. Howard LeWine is a practicing internist at Brigham and Women’s Hospital in Boston, Chief Medical Editor at Harvard Health Publishing, and editor in chief of Harvard Men’s Health Watch. See Full Bio View all posts by Howard E. LeWine, MD

If you’re struggling with depression, the most important question about taking an antidepressant is whether it will work. But another question on your mind may be whether it will fuel weight gain.

A new study provides some context by suggesting how much weight, on average, people taking one of eight commonly used antidepressants might expect to gain. This insight is valuable, since people with depression often stop taking antidepressants because they don’t like the effect on their weight, a Harvard expert says.

“It’s important to acknowledge that weight gain is a key reason that some people decide to stop antidepressants, even if they’re otherwise working well,” says Dr. Roy Perlis, associate chief of psychiatric research at Massachusetts General Hospital. “It’s also a reason people may be reluctant to start them in the first place, even if they’re quite depressed or anxious.”

What did the study look at?

Published July 2024 in Annals of Internal Medicine, the new study drew on data from more than 183,000 people between ages 20 and 80. Their average age was 48, and 65% were women. Most were overweight or obese at the study’s start.

The researchers analyzed participants’ electronic health records and body mass index. They gauged weight gain or loss at regular intervals — six, 12, and 24 months — after people began taking an antidepressant for the first time.

The study compared the weight-related effects of sertraline (Zoloft) to seven other antidepressant medications:

• escitalopram (Lexapro)
• paroxetine (Paxil)
• duloxetine (Cymbalta)
• citalopram (Celexa)
• fluoxetine (Prozac)
• venlafaxine (Effexor)
• bupropion (Wellbutrin).

What did the research find?

The antidepressants led to the following average weight gain:

• sertraline: Nearly 0.5 pounds at six months; 3.2 pounds at 24 months
• escitalopram: 1.4 pounds at six months; 3.6 pounds at 24 months
• paroxetine: 1.4 pounds at six months; 2.9 pounds at 24 months
• duloxetine: 1.2 pounds at six months; 1.7 pounds at 24 months.

Citalopram, fluoxetine, and venlafaxine didn’t confer lower or higher odds of weight gain than Zoloft, the study found. And only bupropion was associated with a small amount of weight loss — 0.25-pounds — at six months. But that trend reversed at 24 months, when bupropion led to an average weight gain of 1.2 pounds.

What does the study tell us?

“Weight gain is common among antidepressant users, even if the amounts gained on average are modest,” says Dr. Perlis, who was not involved in this new study. It underscores similar findings from other studies of antidepressants, including research he published with colleagues a decade ago.

“While differences in weight gain for specific antidepressants tend to be small, there are certainly some — like bupropion — that tend to cause less weight gain,” he notes.

It’s crucial to keep in mind that the study points out average weight gain. Many people taking antidepressants won’t gain any weight and others could gain more. “Still, having average values to work with — and seeing that these averages line up well with prior studies — at least lets us give people a sense of what they might expect,” he says.

“One caution is that some people lose weight as a result of depression, which can impact appetite,” he adds, “so some of what we’re seeing may be people regaining weight they’d lost as their depression or anxiety improves.”

What additional limitations did the study have?

Other limitations may have shaped the findings. The study was observational, meaning it cannot prove that antidepressants cause weight changes, only that they were linked with them. It wasn’t a randomized, controlled trial — considered the gold standard in research — and the participants taking antidepressants weren’t compared to a control group not taking the medications.

Additionally, only about one in three participants was still taking their initially prescribed medication six months after the study started. That makes it difficult to link any later weight changes with a specific medication.

“As with any study that’s not randomized, we don’t know if the differences between medicines could reflect other differences in who gets prescribed these medicines,” Dr. Perlis says. “But, for circumstances where a randomized trial is unrealistic, health records can be a helpful way of trying to study side effects and at least generate a partial answer to these important questions.”

What else should you consider?

Another thing to consider, if you’re taking an antidepressant, is what types of side effects you’re willing to tolerate in pursuit of its mood-smoothing benefits.

“The best way to manage side effects is to anticipate them — to have an open conversation with your doctor about the potential risks and how we’ll manage them if they occur,” Dr. Perlis says.

What can you discuss with your doctor?

If weight gain is a particular concern for you, you may also wish to consider nondrug treatments for depression. They include:

• Cognitive behavioral therapy (CBT), a type of psychotherapy that teaches people to become aware of their thought patterns and adjust them during stressful moments to reframe their thinking.
• Repetitive transcranial magnetic stimulation (rTMS), a brain stimulation therapy that is noninvasive. It uses an electromagnetic coil placed on the scalp to deliver magnetic pulses that stimulate nerve cells to brain regions involved in depression.

“We know that certain kinds of talk therapies, especially cognitive behavioral therapy, can be very effective for treating depression and anxiety disorders,” Dr. Perlis says. “Whether people choose talk therapy or antidepressant medications can depend on their preference. It’s important to have multiple options.”

About the Author

Maureen Salamon, Executive Editor, Harvard Women's Health Watch

Maureen Salamon is executive editor of Harvard Women’s Health Watch. She began her career as a newspaper reporter and later covered health and medicine for a wide variety of websites, magazines, and hospitals. Her work has … See Full Bio View all posts by Maureen Salamon

About the Reviewer

Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing

Dr. Howard LeWine is a practicing internist at Brigham and Women’s Hospital in Boston, Chief Medical Editor at Harvard Health Publishing, and editor in chief of Harvard Men’s Health Watch. See Full Bio View all posts by Howard E. LeWine, MD

Not so long ago, a friend texted me from a coffee shop. He said, "I can't believe it. I'm the only one here without a tattoo!" That might not seem surprising: a quick glance around practically anywhere people gather shows that tattoos are widely popular.

Nearly one-third of adults in the US have a tattoo, according to a Pew Research Center survey, including more than half of women ages 18 to 49. These numbers have increased dramatically over the last 20 years: around 21% of US adults in 2012 and 16% of adults in 2003 reported having at least one tattoo.

If you're among them, some recent headlines may have you worried:

              Study Finds That Tattoos Can Increase Your Risk of Lymphoma (OnlyMyHealth)

              Getting a Tattoo Puts You At Higher Risk of Cancer, Claims Study (NDTV)

              Inky waters: Tattoos increase risk of lymphoma by over 20%, study says (Local12.com)

              Shocking study reveals tattoos may increase risk of lymphoma by 20% (Fox News)

What study are they talking about? And how concerned should you be? Let's go through it together. One thing is clear: there's much more to this story than the headlines.

Why are researchers studying a possible link between tattoos and lymphoma?

Lymphoma is a type of cancer that starts in the lymphatic system, a network of vessels and lymph nodes that twines throughout the body. With about 90,000 newly diagnosed cases a year, lymphoma is one of the most common types of cancer.

Risk factors for it include:

• advancing age
• certain infections (such as Epstein-Barr virus, HIV, and hepatitis C)
• exposure to certain chemicals (such as benzene, or possibly pesticides)
• family history of lymphoma
• exposure to radiation (such as nuclear reactor accidents or after radiation therapy)
• having an impaired immune system
• certain immune diseases (such as rheumatoid arthritis, Sjogren's disease, or celiac disease).

Tattoos are not known to be a cause or risk factor for lymphoma. But there are several reasons to wonder if there might be a connection:

• Ink injected under the skin to create a tattoo contains several chemicals classified as carcinogenic (cancer causing).
• Pigment from tattoo ink can be found in enlarged lymph nodes within weeks of getting a tattoo.
• Immune cells in the skin can react to the chemicals in tattoo ink and travel to nearby lymph nodes, triggering a bodywide immune reaction.
• Other triggers of lymphoma, such as pesticides, have a similar effect on immune cells in lymph nodes.

Is there a connection between tattoos and lymphoma?

Any potential connection between tattoos and lymphoma has not been well studied. I could find only two published studies exploring the possibility, and neither found evidence of a compelling link.

The first study compared 737 people with the most common type of lymphoma (called non-Hodgkin's lymphoma) with otherwise similar people who did not have lymphoma. The researchers found no significant difference in the frequency of tattoos between the two groups.

A study published in May 2024 — the one that triggered the scary headlines above — was larger. It compared 1,398 people ages 20 to 60 who had lymphoma with 4,193 people who did not have lymphoma but who were otherwise similar. The study found that

• lymphoma was 21% more common among those with tattoos
• lymphoma risk varied depending on how much time had passed since getting the tattoo:
  • within two years, lymphoma risk was 81% higher
  • between three and 10 years, no definite increased lymphoma risk was detected
  • 11 or more years after getting a tattoo, lymphoma risk was 19%

There was no correlation between the size or number of tattoos and lymphoma risk.

What else should you know about the study?

Importantly, nearly all of the differences in rates of lymphoma between people with and without tattoos were not statistically significant. That means the reported link between lymphoma and tattoos is questionable — and quite possibly observed by chance. In fact, some of the other findings argue against a connection, such as the lack of a link between size or number of tattoos and lymphoma risk.

In addition, if tattoos significantly increase a person's risk of developing lymphoma, we might expect lymphoma rates in the US to be rising along with the popularity of tattoos. Yet that's not the case.

Finally, a study like this one (called an association study) cannot prove that a potential trigger of disease (in this case, tattoos) actually caused the disease (lymphoma). There may be other factors (called confounders) that are more common among people who have tattoos, and those factors might account for the higher lymphoma risk.

Do tattoos come with other health risks?

While complication rates from reputable and appropriately certified tattooists are low, there are health risks associated with tattoos:

• infection, including bacterial skin infections or viral hepatitis
• allergic reactions to the ink
• scarring
• rarely, skin cancer (melanoma and other types of skin cancer).

The bottom line

Despite headlines suggesting a link between tattoos and the risk of lymphoma, there's no convincing evidence it's true. We'll need significantly more research to say much more than that. In the meantime, there are more important health concerns to worry about and much better ways for all of us to reduce cancer risk.

About the Author

Robert H. Shmerling, MD, Senior Faculty Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing

Dr. Robert H. Shmerling is the former clinical chief of the division of rheumatology at Beth Israel Deaconess Medical Center (BIDMC), and is a current member of the corresponding faculty in medicine at Harvard Medical School. … See Full Bio View all posts by Robert H. Shmerling, MD