A study of more than 17,700 US adults found that people who use cannabis in multiple forms have dramatically higher rates of daily consumption and addiction symptoms than those who stick primarily to one method. Nearly 67% of those who used almost every form met criteria for cannabis use disorder, compared with just 15% of people who mainly consumed edibles.

A new study warns that permanent daylight saving time could force American children to make at least 2 billion additional school commutes in darkness, potentially increasing safety risks and disrupting their biological clocks. Researchers found that fatal crashes involving school-aged pedestrians were roughly twice as likely during dark mornings as after sunrise.

Scientists have uncovered an unexpected connection between inflammation during pregnancy, placental damage, and autism-like traits in male mice, while females appeared naturally protected. The discovery could help explain why autism is diagnosed more frequently in boys and reveal new opportunities for early intervention.

A massive study of nearly 486,000 adults found that regularly drinking tea was associated with an 11% lower risk of heart and blood vessel diseases. The lowest risk was linked to drinking roughly six to eight cups per day, with black tea showing more consistent benefits than green tea.

Scientists have identified a weakened brain signal that may connect several seemingly unrelated symptoms of schizophrenia, including sensory processing difficulties, disorganized speech, and greater symptom severity. The surprising discovery could help explain the disorder's underlying mechanisms and potentially lead to earlier detection and new treatments.

Three high school friends from Alexandria, Virginia—Daniil Prokofev and Ashwath Muppa, both 17, and Isaac Leetyn, 18—are making headlines for creating SafeWalkr, an app that shows the best and safest routes for walking or biking to school. After Prokofev experienced the danger of navigating home from school on foot, he enlisted his friends to create something made for pedestrians rather than drivers. The three teens got to work, won their school’s 24-hour hackathon, and continued working for months to perfect the app. SafeWalkr uses data from county records, Google Maps, and other sources, while considering important factors like traffic and the availability of sidewalks. This month, the app went live for students at 14 schools in Fairfax County, Virginia, with plans to expand to more soon. The timing could not be better: In recent weeks, Fairfax County has seen multiple accidents involving cars colliding with students on bikes or scooters, including one fatality.

A study of nearly 90,000 adults found that people consuming the most of a little-known sugar found in red meat had a 63% higher risk of developing type 2 diabetes. Scientists suspect the sugar may trigger chronic inflammation, potentially revealing a hidden connection between red meat and diabetes that goes beyond weight gain.

Scientists have discovered that a protein linked to youth helps protect the brain’s immune cells from age-related decline. Restoring the protein in older mice improved the cells’ ability to clear debris and reduced signs of inflammation, raising hopes for future treatments targeting brain aging and Alzheimer’s disease.

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.