Age differences in broader autism phenotype traits from young adulthood to older adulthood.

Much of past research has been dedicated to refining the operationalization and correlates of the broader autism phenotype (BAP) and less on how the BAP differs by socio-demographic characteristics, like age-particularly after midlife. This gap is important because other nonclinical trait-like characteristics (e.g., personality) have shown considerable age differences, leading to work assessing the malleability of psychological characteristics and improving outcomes for individuals and their significant others. In the current study, we examined cross-sectional age differences in the BAP in a large sample of adults ranging in age from 18 to 85. We recruited a sample of 2966 adults ranging in age from 18 to 85 (M = 36.53, SD = 12.61; 58.9% Female; 1.1% with an ASD diagnosis) recruited from an online survey service. We found that total BAP scores were higher in younger adults and lower among older adults. These differences were particularly true for pragmatic language difficulties, with this component of the BAP showing the most dramatic age differences. Aloofness showed similar negative associations with age, albeit much smaller. Rigidity was not significantly associated with age. The results are consistent with other research showing an abatement of symptoms among individuals with autism spectrum disorders (ASDs) across early life and theories predicting changes in other psychological characteristics (e.g., personality). The results are discussed in the context of the malleability of ASD and BAP traits across life, the clinical implications of these changes, and the origins and consequences for lifespan differences in BAP. LAY SUMMARY: Little is known about how subclinical autistic-like traits among middle-aged and older adults compare to younger adults. We found that these subclinical traits were highest in young adults and lowest in older adults. Knowing how these traits differ by age can provide researchers and clinicians with a sense of how much these traits might change across life, if the traits might be sensitive to interventions, and when in development it might be best to intervene.