Study finds autism-related early brain overgrowth slows by age 2 years

May 2, 2011
These images show brain maturation measured by cortical thickness for a representative subject with autism at age 2 (left) and age 4 (right). Thicker areas of cortex are shown in red, while thinner cortical areas are displayed in green. Credit: Image created by Clement Vachet, Neuro Image Research and Analysis Laboratories, UNC Department of Psychiatry.

Scientists using magnetic resonance imaging (MRI) observed that the brains of children with autism spectrum disorder are larger than those without autism, but this difference appears related to increased rates of brain growth before 2 years of age, according to a report in the May issue of Archives of General Psychiatry.

Autism researchers have long known of the connection between the and an increase in , although the cause and timing are not well defined. "The timing of brain enlargement in autism is of particular importance," note the authors of the present study. Other research has suggested "a period of typical development followed by the early postnatal onset of autistic disorder in the latter part of the first year or early second year of life." Linking the appearance of symptoms with the period of rapid could provide information for investigating the causes of the disorder.

Heather Cody Hazlett, Ph.D., of the University of North Carolina, Chapel Hill, and colleagues evaluated 59 children with (ASD) and 38 children who did not have an ASD diagnosis. The investigators conducted behavioral assessments and obtained MRIs of the participants' brains at age 2. Roughly two years later, when the children were 4 to 5 years old, the steps were repeated among a smaller group available for follow-up (36 children with an ASD diagnosis and 21 without). Scans were evaluated for the volume of gray and white matter in the brain, and the thickness of the brain cortex.

Children with ASD showed enlargement of the volume at all ages studied. However, the rate of brain growth was similar to the rate seen in children who did not have ASD. Researchers noted that cortical thickness was similar in both groups but that the ASD group exhibited both a greater cortical surface area and an increase in white matter in the temporal lobe. The authors also found that there was "no increased rate of cerebral cortical growth during this age interval" (i.e., between age 2 years and age 4 to 5 years), suggesting that "increased brain volume at age 2, largely due to increased cerebral cortical volume, results from an increased rate of brain growth occurring before 2 years of age."

Based on these findings, the authors suggest that "brain overgrowth had its onset in the latter part of the first year of life," noting that "direct evidence of the timing of early brain volume overgrowth in autism will focus future studies on this narrow window of brain development." Further, the researchers state, identifying the timeframe when brain changes occur can help isolate " markers that may increase prediction of ASD risk."

More information: Arch Gen Psychiatry. 2011;68[5]:467-476.

Related Stories

Recommended for you

Probing how Americans think about mental life

October 20, 2017
When Stanford researchers asked people to think about the sensations and emotions of inanimate or non-human entities, they got a glimpse into how those people think about mental life.

Itsy bitsy spider: Fear of spiders and snakes is deeply embedded in us

October 19, 2017
Snakes and spiders evoke fear and disgust in many people, even in developed countries where hardly anybody comes into contact with them. Until now, there has been debate about whether this aversion is innate or learnt. Scientists ...

Dutch courage—Alcohol improves foreign language skills

October 18, 2017
A new study published in the Journal of Psychopharmacology, conducted by researchers from the University of Liverpool, Maastricht University and King's College London, shows that bilingual speakers' ability to speak a second ...

Inflamed support cells appear to contribute to some kinds of autism

October 18, 2017
Modeling the interplay between neurons and astrocytes derived from children with Autism Spectrum Disorder (ASD), researchers at University of California San Diego School of Medicine, with colleagues in Brazil, say innate ...

Study suggests psychedelic drugs could reduce criminal behavior

October 18, 2017
Classic psychedelics such as psilocybin (often called magic mushrooms), LSD and mescaline (found in peyote) are associated with a decreased likelihood of antisocial criminal behavior, according to new research from investigators ...

Taking probiotics may reduce postnatal depression

October 18, 2017
Researchers from the University of Auckland and Otago have found evidence that a probiotic given in pregnancy can help prevent or treat symptoms of postnatal depression and anxiety.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.