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This article is more than five years old. Autism research — and science in general — is constantly evolving, so older articles may contain information or theories that have been reevaluated since their original publication date.
Boys who have autism-like social deficits at 2 years of age retain about the same level of social impairment when they reach age 20, according to a study published 4 August in PLoS ONE1.
The results support the existence of a ‘broad autism phenotype,’ which suggests that autism is a continuum that extends throughout the general population. Several studies show that biomarkers of autism, such as abnormal eye movements and difficulty recognizing faces, are shared by unaffected parents and siblings.
Autism is a stable diagnosis that generally does not change across an individual’s lifetime2. In the new study, researchers followed 760 young adults in the general population who were given the Child Behavior Checklist at age 2 as part of the Western Australian Pregnancy Cohort (Raine) Study.
The researchers measured autism traits in the same individuals when they reached 19 to 20 years of age, using the Autism Spectrum Quotient, a self-reporting questionnaire that measures autism traits in adults.
The 360 men in the study had mean levels of autism traits at 19 years of age similar to the levels they had as toddlers, the study found. Their social deficits remained at about the same level over the years, whereas other autism traits, including restricted and repetitive behaviors, did not.
The boys with the highest scores for autism traits remained in that percentile for their social scores, but not for their non-social scores, the study also found. This suggests that repetitive behaviors are more likely to improve over time in the general population than are social deficits.
By contrast, mean levels of autism traits for the 400 young women changed significantly between 2 and 20 years of age. This could either be because the measures are less effective at detecting autism traits in adult women than in men, the researchers say, or because autism traits develop differently in women than in men.
1: Whitehouse A.J. et al. PLoS One Epub ahead of print (2011) PubMed
2: Eaves L.C. and H.H. Ho J. Aut. Dev. Disord. 38, 739-747 (2008) PubMed