Changes in diagnostic practices, more active neighborhood networks, and an increase in the number of older parents may all contribute to the massive rates of autism in California, says a group of social scientists. But the numbers still don’t add up.

The Autism Birth Cohort, based on data from 100,000 Norwegian children and their families, aims to uncover genetic and environmental factors contributing to the disorder.

Researchers have uncovered an important molecular piece of a learning mechanism that occurs at the junction between neurons. The findings, which may help understand how the brain is disrupted in disorders such as autism, appear in the 24 June issue of Neuron.

In the not-too-distant future, we may be able to diagnose toddlers with autism using a simple clinical test — based on voice patterns, blood or even urine.

Not all stem cells are created equal, a string of new studies suggests: adult cells that are reprogrammed into stem cells carry chemical remnants of the tissue from which they originate, making them distinct from embryonic stem cells. These differences may have important implications for studying fragile X syndrome and other diseases that arise from epigenetic glitches.

The biology of obsessive-compulsive disorder becomes even more baffling with the release of two new mouse models, each implicating a different type of brain cell.

Autism and intellectual disability often occur together, but in most cases that overlap is not genetic, according to a study of twin pairs published in the American Journal of Medical Genetics. Unraveling this link might help researchers pinpoint brain circuits involved in both conditions, and better understand the diversity of symptoms in the autism spectrum, experts say.

The mouse brain has more than 1,300 regions for which the copy from one parent is expressed more often than the one from the other parent, according to two studies published today in Science. These so-called imprinted genes have been proposed to cause some cases of autism, but the researchers say their findings do not support that theory.

Babies born to rhesus monkeys infected with the flu virus during pregnancy have significantly smaller brains than normal, and other brain abnormalities seen in schizophrenia, researchers have found. The study, published last month in Biological Psychiatry, provides the first evidence in non-human primates linking flu infection to a higher risk of schizophrenia.

Microglia, brain cells that provide immune protection to neurons, may influence the onset and course of Rett syndrome, according to a study published in the Journal of Neuroscience.