Toddlers who abruptly lose language, social or other developmental skills are more likely to have severe autism a few years later compared with children who have consistent delays from an early age. That’s the conclusion of the largest study thus far of autism onset patterns, published in the Journal of Autism and Developmental Disorders.

Scientists have for the first time captured a dynamic picture of brain defects in young mouse models of fragile X syndrome. The findings appeared in June in the Journal of Neuroscience.

Scientists have discovered that neurexins — proteins linked to autism — bind to a wide variety of molecules at the junction between neurons. In this complicated system, the breakdown of any one of the parts could lead to improper cell signaling, ultimately giving rise to disease.

Children with autism have abnormally low brain activity in the ‘reward center’ of the brain when given money or shown a happy face, according to a study in Autism Research. These are the first imaging data to support the notion that children with autism derive less pleasure from social interactions compared with their healthy peers.

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.

A region of the brain that controls language is more extensively curved in children with autism than in those with Asperger syndrome, according to a study published in the Journal of Child Neurology. The findings offer preliminary biological evidence that Asperger syndrome, a disorder on the autism spectrum, is distinct from high-functioning autism.

Individuals carrying an extra copy of the genetic region that’s missing in Williams syndrome — which causes mental retardation and a hyper-friendly personality — have language impairments and other autism-like social difficulties, according to a wave of new research on this duplication syndrome.

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.

Children with fragile X syndrome show abnormal growth in several brain structures during the first few years of life, according to the first study to track how the disease unfolds in the brain during early development.

Several independent groups have found previously unknown risk genes for autism, schizophrenia and mental retardation. The candidate genes have one thing in common: they encode proteins that are needed for the healthy function of synapses, the junctions between neurons.