Feeling scared? Your fear is a survival tool, but sometimes, it overreacts — making us afraid of things that aren’t true threats.  A new study shows how the brain learns to let go of unnecessary fears, offering potential new ways for treating conditions such as anxiety, PTSD and phobias. Published in the journal Science, it tracked how mice responded to repeated harmless threats, such as a shadow that mimicked a predatory bird’s swoop. Over time, the mice learned the shadow wasn’t dangerous and stopped reacting. Scientists found that this “unlearning” of fear was stored in a previously overlooked part of the brain called the ventrolateral geniculate nucleus (vLGN). “We’ve uncovered the mechanism by which the brain — through experience — can understand which potential instinctive dangers are actually not a danger,” study leader Sara Mederos, a neuroscientist at University College London’s Sainsbury Wellcome Center, told The Washington Post. In the study, about 100 mice were exposed to 30 to 50 simulated “swoops,” using an expanding overhead shadow to mimic a bird of prey. By inserting silicon probes in the mice’s brains, scientists discovered that while the visual cortex helped the mice recognize the harmless threat, the vLGN actually helped store the memory to disregard it. By focusing on specific molecules and neurotransmitters released in this area of the brain, researchers think it may be possible…  read on >  read on >

MONDAY, Feb. 24, 2025 (HealthDay news) — Even slight weight loss spurred on by cutting-edge GLP-1 drugs can help prevent replacement knees and hips from wearing out, a new study suggests. People with new knees and hips are significantly less likely to need follow-up surgery to fix wear and tear on their artificial joint if they lose weight using Wegovy, Zepbound or other GLP-1 drugs, researchers reported in a new study published Feb. 21 in JAMA Network Open. Patients who lost 2% to 10% of their initial weight had an overall 25% lower risk of follow-up surgery, and those who lost 10% or more had a 43% lower risk. “A higher proportion of weight loss after initiating antiobesity medications within 1 year was associated with a lower risk of 5-year and 10-year revision among patients with obesity undergoing joint replacement,” concluded the research team led by Dr. Chao Zeng, an orthopedics specialist with Ziangya Hospital at Central South University in Changsha, China. “These results suggest that antiobesity medication use, with relatively safe and sustainable weight loss, may be an effective strategy for improving implant survivorship of hip and knee replacement in the obese population,” researchers added. In the U.S., about 900,000 knee replacement surgeries and 400,000 hip replacements occur each year, researchers said in background notes. Knee replacements can be expected to function well for…  read on >  read on >

People taking the weight-loss drug semaglutide could be at a slightly increased risk for a potentially blinding eye condition that affects the optic nerve, a new study says. Patients on semaglutide (Ozempic, Wegovy) had a 32% increased relative risk of developing nonarteritic anterior ischemic optic neuropathy (NAION) compared to people not taking the drug, researchers reported Feb. 20 in JAMA Ophthalmology. NAION typically causes sudden vision loss in one eye, according to Brigham and Women’s Hospital.  It’s thought to occur due to a loss of blood flow to the optic nerve, damaging the neurons that transmit images to the brain. Previous studies also have detected this risk. A 2024 study based at Mass Eye and Ear in Boston reported a more than fourfold increased risk of NAION with semaglutide, researchers said in background notes. That study also appeared in JAMA Ophthalmology. The new study provides “further evidence of an association between semaglutide and NAION but show a smaller risk than that previously reported,” concluded the research team led by Dr. Cindy Cai, an assistant professor of ophthalmology at Wilmer Eye Institute at Johns Hopkins. However, the new study also found that patients prescribed semaglutide did not have a significantly increased risk for NAION compared with other GLP-1 diabetes medications. More research is needed to confirm this link and to identify why semaglutide might have this…  read on >  read on >

Fainting can be scary, but it’s often harmless. Known medically as syncope, fainting happens when there’s not enough blood flow to the brain, causing a brief loss of consciousness. But how do you know if it’s just a simple faint or something more serious? Dr. Elijah Behr, a cardiologist at Mayo Clinic Healthcare in London, shares five key facts about fainting: what causes it, how to prevent it and when to see a doctor. Most fainting is harmless, but not always The most common type of fainting is vasovagal syncope, often triggered by emotional stress, pain, illness or dehydration. “In some people, if they have a drop in blood pressure from emotional distress, pain, illness or dehydration, for example, or just generally have a low blood pressure, any provocation causes a reflex in the heart,” Dr. Behr explained in a news release. “Rather than the heart speeding up and pumping more forcefully to maintain the blood pressure, it starts to slow down. The blood pressure drops, the heart rate slows further, and the heart can pause for many seconds; sometimes close to a minute for some people who have more severe fainting episodes.” While simple fainting usually resolves quickly, cardiac syncope — caused by an underlying heart problem — can be more serious. “This is usually a more abrupt loss and return of consciousness than…  read on >  read on >