A 47-year study has uncovered a surprising turning point in physical aging: fitness and strength begin declining around age 35, even among people who exercise regularly. Researchers found that this decline accelerates as people get older, but starting to exercise in adulthood can still improve physical performance.

Nicotine e-cigarettes appear to help more smokers quit than patches, gum, and several other common approaches, according to a major review of 80 clinical trials. Researchers say regulated vaping products are not risk-free, but may be a significantly less harmful alternative for people who would otherwise continue smoking.

A study of more than 130,000 babies born in Georgia found that hundreds of fathers died within the first five years of their child’s life, and about 60% of those deaths were potentially preventable. Homicide, accidental injuries, suicide, and drug overdoses accounted for most of the preventable deaths, highlighting what researchers call a major blind spot in public health.

A new study of more than 2,300 grade 6 to 8 students found that the majority use AI chatbots, and their use was increasing. Researchers found that the more students used AI, the more they had symptoms of social anxiety and depression. One in five middle schoolers admitted they relied on AI for “emotional companionship.” While some students turned to AI because they felt lonely, the study showed that it actually tended to increase their feelings of loneliness. One study author said they found two to four kids in most classes who said they preferred chatting with AI rather than people. Since the preteen and teen years are a crucial time for social and emotional development, experts are calling on schools, parents, and companies to put up safeguards around the use of AI by young people.

Scientists have found a surprising way to regrow damaged knee cartilage by blocking a protein that becomes more abundant with age. In old mice, the treatment restored naturally lost cartilage and also helped prevent osteoarthritis after ACL-like knee injuries, while human cartilage taken from knee replacement patients began producing new, functional joint cartilage after exposure to the same inhibitor.

New mothers paired with patient navigators were much more likely to receive postpartum care, depression screening, preventive testing, and ongoing primary care. By helping with barriers such as transportation, childcare, scheduling, and confusing medical information, navigators may provide a powerful way to improve women’s long-term health.

In a small study, sleeping near the scent of Hinoki root essential oil was linked to fewer nighttime awakenings, better morning alertness, and brain-wave changes associated with smoother sleep onset. The findings suggest an overlooked forestry byproduct could someday become a natural ingredient in sleep and relaxation products.

An increasing number of young people are taking glucagon-like peptide-1 (GLP-1) receptor agonist drugs for obesity and diabetes. A new study of more than 2,000 patients ages 10 to 17 found that one in six developed nutritional deficiencies within a year of starting GLP-1s. The most common problem was vitamin D deficiency, found in one in eight study participants. Lack of vitamin D causes issues like muscle weakness, fatigue, and mood problems. Since GLP-1 drugs decrease food intake, they make it easier for people to miss out on key vitamins and minerals. That is especially important for teens. According to study author Dr. Justin Ryder, “Nutrients such as vitamin D, iron, and calcium are of particular concern during adolescence, when deficiencies may have lasting implications for skeletal health and overall development.”

Depression may change which emotional faces children notice most, but the pattern appears to depend on family history. Children at higher familial risk became increasingly focused on sad faces, while lower-risk children with rising symptoms paid less attention to happy ones.

Chronic inflammation tied to stress, lifestyle, mental health, and socioeconomic conditions may silently change the heart for years before any symptoms appear. People with the highest inflammation levels faced a 43% greater risk of heart attack and stroke, raising hopes that earlier testing and anti-inflammatory treatments could help prevent serious heart disease.

Today, a record number of teens are obese, but health experts see some hope in the number of teens turning to sports to stay fit. According to the National Federation of State High School Associations, more than 8.4 million American teens are playing high school sports, more than ever before. Girls are driving the increase. Their participation jumped 3.2 percent over the past year, compared to 0.8 percent for boys. The fastest-growing sport is girls’ flag football, with participation growing by 49 percent in just one year. Thousands of schools across 40 states now offer the sport, and 24 states recognize it as a state-sanctioned varsity sport. That momentum is continuing beyond high school, too. More and more colleges are offering girls’ flag football programs. The sport will also make its Olympic debut at the 2028 Olympic Games in Los Angeles.

Aging may be partly fueled by immune cells losing their ability to clear away damaged, inflammation-promoting cells. Blocking a single receptor restored that cleanup process in mice, reducing inflammation and helping their organs, muscles, and memory remain remarkably youthful.

A New Mexico judge has ordered Meta, the company behind Instagram and Facebook, to pay $567 million into a fund supporting youth mental health treatment and prevention. The court found that features designed to keep teens scrolling—such as endless feeds, recommendations, and notifications—helped contribute to problems like anxiety, depression, eating disorders, and self-harm. The judge called Meta’s platforms a “significant contributing cause” of a teen mental health crisis in the state. Meta must also introduce stronger protections for young users, including limits on screen time, chatbots, and contact between adults and minors. The case highlights growing concerns that social media companies have a responsibility to design their apps with teens’ health and safety in mind.

Scientists have found evidence that the effects of a mother’s age on her offspring may be driven by reversible changes in gene activity rather than permanent DNA damage. The discovery raises the fascinating possibility that biological information from mothers, grandmothers, and even great-grandmothers can shape the health of future generations.

A widely available food-preservation chemical is emerging as a disturbing factor in rising UK suicide deaths, particularly among younger people and men. Researchers say the scale may be underestimated and are calling for urgent restrictions on access and harmful online information.

A surprising stress-related signal may help the brain repair itself after injury. Researchers found that myelin-producing precursor cells rapidly release the stress hormone CRH near damaged brain tissue, helping control how those cells mature and rebuild protective nerve insulation. The same system also influences brain development and the thickness of myelin later in life. The findings could offer new clues about how early-life stress contributes to psychiatric disorders.

Women who used estrogen-only hormone therapy later in life were less likely to develop dementia and showed fewer signs of Alzheimer’s disease in their brains, according to a large study of more than 21,000 participants. Hormone therapy use was linked to 39% lower odds of a dementia diagnosis and 35% lower odds of Alzheimer’s-related brain changes at autopsy, including amyloid plaques and tau tangles. Biomarker tests also suggested less amyloid buildup among hormone therapy users.

Frequent cannabis users may wake up with unusually high levels of the stress hormone cortisol, suggesting their daily stress rhythms could be disrupted. Researchers say the finding raises questions about whether using cannabis for stress relief might, over time, interfere with the very system that helps the body handle stress.

Teens who start using cannabis may experience slower growth in memory, attention, language, and processing speed. Their abilities often developed normally at first, then began leveling off while nonusers continued improving. THC appeared to be the most likely driver, especially for worsening memory.

New research challenges the decades-old idea that children experience an “adiposity rebound” when their BMI begins rising around age 6. Although BMI returns to earlier levels, a more reliable measure showed that body fat does not rebound at all. The increase appears to come from growing muscle and lean tissue as children prepare for later growth. Researchers say this normal process has been mistakenly treated as an obesity warning sign for 42 years.