Regular marijuana use in adolescence may permanently impair brain function, cognition and increase the risk of developing serious psychiatric disorders such as schizophrenia, according to a recent study in Neuropsychopharmacology.

Stem cell gene therapy has been used to treat a fatal genetic brain disease - Sanfilippo, which in human children causes progressive dementia and death - in mice for the first time. 

The researchers are hoping to begin a clinical trial within two years.

Male guppies must not be very sexy, because they have evolved an extreme way to hold on to a female that interests them, even if that affection is unrequited: claws on their genitals to make it more difficult for unreceptive females to get away during mating.

Walking helps people in lots of ways but a paper in the Archives of Pediatrics & Adolescent Medicine (now JAMA Pediatrics) has a new benefit; adolescent girls who walk to school show a cognitive boost compared to girls who travel by bus or car.

But distance matters. Girls who walk more than 15 minutes showed more benefit than those who live closer and have a shorter walk to school.

The results come from findings of the nationwide AVENA (Food and Assessment of the Nutritional Status of Spanish Adolescents) study, which they say is the first international study that associates mode of commuting to school and cognitive performance.

The rate of unnecessary cancer scans for low-risk prostate cancer patients - the kind of defensive medicine that is a large chunk of medical costs in America - plummeted in Sweden in the decade following a joint campaign to curtail such tests by Swedish County Councils and the National Prostate Cancer Register (NPCR) of Sweden. 

The results in the Journal of the National Cancer Institute suggest that reducing the costs of healthcare in the US - an urgent priority now that the government has mandated it and intends to subsidize it - can be achieved without significant risk.

What's the diet for a high performance athlete? Despite the cultural pendulum of fad diets swinging back toward fat, high fiber, low-fat foods balanced with a training regimen remains the best way to maintain muscle while burning fat.