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.

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.

There are valley networks branching across the Martian surface, which makes it reasonable to believe that water once flowed on the Red Planet.

Where water might have come from would be another mystery. Whether it bubbled up from underground or fell as rain or snow is the subject of speculation and debate but a new study says it can put a new check mark in the 'precipitation' column. The authors say that water-carved valleys at four different locations on Mars appear to have been caused by runoff from orographic precipitation — snow or rain that falls when moist prevailing winds are pushed upward by mountain ridges.

My vague libertarian leanings want me to stay out of the marijuana issue, just like I don't interfere in vaginas and just like I think the government should stop micromanaging gold fish and Big Gulps and telling restaurants whether or not to allow a cigar after a great steak.

But marijuana has become a political issue and it has fallen along predictable political lines; if you think cigarettes should be banned and marijuana legalized, I know how you vote. And therefore the people suddenly presenting nonsense statistics, dubious medical claims and sociological woo are seemingly doing it because they want to stick it to right wing people who are against pot.  That's not science, people.

Food waste is a big problem, particularly in the developing world, but also in the rich world.   I have seen quite a bit written recently about how one of the best ways to improve the sustainability and lower the footprint of food production would be to reduce waste.  While this is absolutely true, the perspective that has been missing is that we have been working on this issue for a very long time and have made significant advances over the last several decades.

Concerned parents have been worried about the potential impact of exposure to low levels of mercury on the developing brain, such as when pregnant women consume fish, and that has led to claims that the chemical may be responsible for behavioral disorders such as autism.

The main active constituent of cannabis - tetrahydrocannabinol or THC - has not shown to be effective in slowing the course of progressive multiple sclerosis (MS).

The CUPID (Cannabinoid Use in Progressive Inflammatory brain Disease) study was carried out by researchers from Plymouth University Peninsula Schools of Medicine and Dentistry,the Medical Research Council Clinical Trials Unit and University College London and is the first large, non-commercial clinical study of THC for MS progression.