Brief report: bidirectional association of core autism features and cognitive abilities in early childhood.

We explored associations among the core behavioural features and developmental/cognitive abilities of 155 autistic children, assessed between ages 13-67 months and again around 1-year later to understand predictive directionality. Bidirectional, cross-domain association was apparent, albeit with stronger direction of effect from earlier cognition to later autism features (than vice versa). Exploratory sub-domain analysis showed that early non-verbal developmental/cognitive abilities (only) predicted subsequent social- and restricted/repetitive autism features, whereas early social features (only) predicted both subsequent verbal and non-verbal abilities. Although observational study design precludes causal inference, these data support contemporary notions of the developmental interconnectedness of core autism presentation and associated abilities-that behavioural autism features may influence cognitive development, but are likely also influenced by an individuals' cognitive capacity.