A common characteristic of autism - language delay in early childhood - leaves a definite "signature" in the brain, says new research.
Delayed language onset - defined as when a child's first meaningful words occur after 24 months of age or their first phrase occurs after 33 months of age - is seen in a subgroup of children with autism.
"Language development and ability is one major source of variation within autism. This new study will help us understand the substantial variety within the umbrella category of the 'autism spectrum'," said Dr Meng-Chuan Lai from the University of Cambridge's autism research centre.
The researchers studied 80 adult men with autism: 38 who had delayed language onset and 42 who did not.
They found that language delay was associated with differences in brain volume in a number of key regions.
Additionally, they found that current language function is associated with a specific pattern of grey and white matter volume changes in some key brain regions - particularly temporal, frontal and cerebellar structures.
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The findings show how the brain in men with autism varies based on their early language development and their current language functioning.
"This suggests there are potentially long lasting effects of delayed language onset on the brain in autism," researchers concluded in a paper published in the journal Cerebral Cortex.