MS risk is shaped by geography, not just genes

Latitude—and related vitamin D exposure—seems to affect MS risk. People who migrate from a high-risk MS latitude (like northern Europe or the northern US) to a lower-risk latitude (like tropical areas) before age 15 tend to adopt the lower risk of their new country—suggesting there's a critical window for environmental exposure.

Cigarette smoke exposure boosts MS risk by up to 55%, though smokeless tobacco doesn't

The components of the smoke itself are associated with these significantly increased risks, so it's something beyond nicotine itself that drives that risk. What's more, smoking also increases the risk of developing antibodies to MS-treating drugs.

Epstein-Barr virus—the cause of 'kissing disease' mononucleosis—may be the leading cause of MS

A Harvard study with data from more than 10 million US military personnel found that people that contracted Epstein-Barr virus had a roughly 32-fold increased risk of developing multiple sclerosis. The work, published in 2022, found that Infection of the virus preceded MS onset by a median of five years, raising questions about better Epstein-Barr virus management and potential disease prevention.

A vaccine against Epstein-Barr virus, researchers hypothesize, could potentially prevent MS

As many as a quarter of MS patients have antibodies in their blood that bind to both a central protein in Epstein-Barr virus and a protein made in the brain and spinal cord that—when attacked—leads to a breakdown of protective nerve fiber insulation. This suggests the immune system's primed to attack the nervous system after mounting a defense against Epstein-Barr.

Autoimmune disease prevalence and incidence are on the rise—but no one knows why

Researchers theorize that environmental factors, including shifts to less healthy diets, air pollution, infections, stress, climate change, and exposures to xenobiotics—substances like pesticides, plastics, and toxins that incite immune responses—may all be fueling epigenetic changes to our bodies that make people's immune responses go awry.

MS can damage the brain up to 7 years before symptoms appear

Recent research scouring blood samples from 134 people with MS, both before and after their diagnosis, found that about seven years before these patients were diagnosed, there was a spike in a protein called myelin oligodendrocyte glycoprotein—indicating disease-associated damage to the protective myelin around nerve fibers.

People with blue eyes appear to be at elevated risk of developing macular degeneration, perhaps because more light can penetrate their eyes.

MS Drugs reduce inflammation, helping reduce relapses and slow disease progression

Disease-Modifying Drugs calm the body's inflammatory response to help stave off relapses—when new or existing MS symptoms show up for a day or longer. Avoiding smoking, exercising, reducing stress via mindfulness, checking for vitamin D deficiencies, drinking more water and eating well, all can slow disease progression. [The jury's still out on if HRT around the time of menopause may reduce dementia risk](https://www.thelancet.com/journals/lanhl/article/PIIS2666-7568(25)00122-9/fulltext) Estrogen can reduce inflammation and support neural growth in the brain, and some research has suggested that beginning hormone replacement therapy around menopause—versus later in life—reduces Alzheimer's disease risk. Still, a recent systematic review concluded that taking HRT didn't affect dementia risk, regardless of when women started taking it, so the science remains unsettled.

Females are diagnosed with MS roughly 3 to 4 times more often than males

This PBS documentary traces a filmmaker's personal journey with MS after being diagnosed at age 26. It encompasses both his efforts to stymie the disease's progression and his search for answers about the disease, when, statistically, he seemed at low risk due to his gender, lack of known family risk, and other factors.

Vitamin D supplement pills are linked to rising cases of vitamin D toxicity in the US

Vitamin D deficiency is common. But taking Vitamin D supplements in doses exceeding 4,000 IU/day (a measurement of vitamin biological activity) for prolonged periods can raise bodily concentrations of this vitamin to dangerous values. US National Poison Data indicates that the annual average of vitamin D poisonings from 2000-05 was 196, but this rose by 1,600% to 4,535 per year for the period of 2005-11.

Risk factors linked with ASD include older parents, preterm births, and toxic prenatal exposures

Though researchers agree that there is a strong genetic component to ASD development, certain environmental factors heighten that risk, with studies suggesting older parents, premature birth, maternal obesity, and air pollution exposure in utero all elevate risks of ASD development. There is no connection between receiving vaccines and ASD development.

Eczema appears to heighten the risk of developing shingles.

Caucasians are at the greatest risk of developing macular degeneration

A 2016 analysis across ethnic groups found, among other things, that white participants had the highest incidence of the disease, followed by Chinese, Hispanic, and Black participants. This study did not answer why that may be the case.

Some data links schizophrenia to older paternal age and birth complications

Yet both associations are not yet considered firm enough to definitively be causative. Schizophrenia is a multi-causal syndrome and a mixture of factors, including genetics, are widely believed to be behind its development.

Stroke risk doubles each decade after age 55

While age is the greatest risk factor, genetics, diet, and overall health play a prominent role in determining individual stroke risk. Prevention focuses heavily on modifiable risk factors. High blood pressure is the single most important controllable risk factor, contributing to both types of stroke.

Environmental conditions, shifting immunity, and viral strain could help explain 2025 spike

The surge in HFMD in the summer and early fall of 2025 in the mid-Atlantic could be the result of a confluence of factors, including a more virulent strain of disease-causing virus, good environmental conditions for the virus to spread—hot, humd—and a potential immunity gap among kids due to milder HFMD outbreaks the previous year.

Unlike America's recommendations, Australian authorities don't encourage routine sunscreen use for darker skin tones—reasoning that melanoma risk is low, and it's better to get UV exposure to help the body naturally produce vitamin D.

Even if you have some ASD-linked gene variations you may not develop ASD

Individual environment and life experiences affect how genes perform in the body, potentially adding methyl groups to DNA that affect their function and turning genes on and off—which may heighten or reduce disease risk.

Vitamins can slow macular degeneration

Research published in 2022 affirmed that vitamin formulations containing vitamins C and E, copper, zinc, lutein, and zeaxanthin—but no beta carotene—can enhance eye health and slow the progression of macular degeneration.

More than 20 mosquito-borne and tick-borne diseases are found in the US

Children, older adults, and people with compromised immune systems are at particular risk of poorer health outcomes from these diseases. But dog owners and outdoor enthusiasts are among those at particular risk of contracting these illnesses, which include Lyme disease, Zika, and the condition Alpha-gal Syndrome.

See MS prevalence by region in the United States

This map underscores that people in the northeastern United States have more cases of the disease as compared to the south, west, and midwest. On an individual level, these numbers may still differ based on genetic makeup and other factors irrespective of where people live.

Alzheimer's disease is the leading cause of dementia and risks rise after age 65

Read this primer about Alzheimer's disease and learn what factors increase the risk of this form of dementia, including genetics, being a woman, and health conditions, including high blood pressure.

Twin studies helped scientists understand why mosquitoes like some of us more than others

A combination of carbon dioxide output, skin chemistry, genetic factors, hormones, and clothing choice can make us particularly vulnerable to mosquito bites. Watch how mosquitoes responded to one man in the video versus his wife, a research approach typically conducted with identical and fraternal twins to test mosquito attractiveness.

MS disproportionately sickens women, but men tend to have worse outcomes

Though the disease is more common in women, men's symptoms progress more quickly, with men more often diagnosed with progressive MS and men's cases typically resulting in more severe symptoms—perhaps due at least partly to more delayed diagnosis—and more severe disability over time.

Exposure to ionizing radiation from nuclear accidents can damage DNA

The damage can increase the risks of cancer, cataracts, heart disease, and other illnesses based on exposure times and intensities. Contaminated food, water, air, or soil from near nuclear accidents can further prolong one's exposure.

Changes in vision or eye pain can be early MS symptoms

This occurs due to myelin degradation around the optic nerve, impairing its ability to transmit visual information to the brain. Individuals may especially experience eye symptoms after exercising or taking a hot shower because boosted body temperatures slow down nerve function in nerves already damaged by MS.

Almost 80% of people diagnosed with autoimmune diseases are women

Yet it's still unanswered what may account for that difference. To better understand this disparity researchers are exploring factors including hormonal changes that occur around puberty, pregnancy, and menopause, as well as gut microbe differences, and aspects of X-chromosome protein-coding genes. (Some users may encounter a paywall.)

Cancer rates are on the rise among GenXers and Millennials

Cancer rates are rising among Gen X and Millennials, with more cancer diagnoses being made in their 30s and 40s than previous generations. Factors such as prenatal exposures, environmental toxins, and lifestyle choices may contribute to this trend. Memorial Sloan Kettering Cancer Center's experts discuss these issues, exploring how these insights could reshape cancer risk understanding.

Multiple sclerosis means 'many scars'

That's a reference to the scarring or lesions that occur in the brain, spinal cord, and elsewhere whenever the immune system has a flare-up. The immune system attacks the myelin because it incorrectly responds as if it's a threat, damaging the body's ability to transmit electrical signals effectively from areas of the body to the brain.

Multiple genes are associated with Alzheimer's risk, but one particularly well-known disease-associated gene is apolipoprotein E (APOE), which typically encodes a protein that helps carry cholesterol and other fats in the bloodstream.

Why are women more likely to suffer autoimmune diseases than men?

A majority of Americans with autoimmune diseases have more than one X chromosome, a typical marker of the female biological sex, according to a study published in February of 2024. During fetal development, cells side with one X chromosome over the other, preventing the overproduction of X-chromosome-specific proteins and shutting down the twin chromosome. This article explores how this X-chromosome inactivation can lead to autoimmune disorders by generating antibodies to the body's own tissues.

People with schizophrenia have triple the risk of developing diabetes

It remains contentious if something inherent about the disease or antipsychotics' side effects (weight gain) are mostly to blame. Some newly diagnosed schizophrenia patients already have insulin resistance, raising questions about if patients' brains are getting enough energy from glucose, and if dietary changes—like a high-fat, low-carbohydrate, moderate-protein diet—may help alleviate symptoms.

Ultraprocessed foods are linked with a 58% elevated risk of developing dementia.

80% of schizophrenia cases may be inherited

Some research suggests that anywhere between 60% and 80% of people with schizophrenia had genes that predisposed them to the syndrome. That high rate has fueled interest in further exploration of what environmental and lifestyle factors cause some people with that genetic risk to develop the disease when others with the same genetic risks do not.

Sitting 10+ hours per day increases dementia risk

People who sit for at least 10 hours per day are more likely to develop dementia, according to a study published in 2023. This article details the study on the murky relationship between brain health and prolonged sitting. This study involved...

Chronic exposure to traffic noise is associated with a higher risk of Parkinson's disease.

Yes, you can take too many vitamins and they can make you sick

Too much of vitamins A, D, E, and K (which are fat-soluble) can build up in the body and cause serious health problems, including liver damage, kidney stones, and blood clotting irregularities. Excess iron and calcium can also make it harder for the body to absorb other needed nutrients.