Longitudinal relations between autistic-like features and functional somatic symptoms in adolescence.

The study was observational, so it cannot show that autistic-like features cause functional somatic symptoms or the reverse. Attrition was not random: participants with more severe symptoms were more likely to drop out, which may have made the associations look weaker than they really were. Some reported body symptoms might have had an undetected medical cause, even though the measure asked about symptoms without known origin. The autistic-like features measure included some behaviours that are not specific to autism, such as self-regulatory problems also seen in attention deficit hyperactivity disorder and oppositional defiant disorder. The assessments were spaced across adolescence, so reciprocal effects happening between waves could have been missed. The planned sex covariate was dropped because the model did not converge, and sex was handled by comparing separate groups instead. Participants missing data on three or more waves were excluded.

The authors declared no potential conflicts of interest. Funding came from many Dutch and European research grants, including the Netherlands Organization for Scientific Research, ZonMw, the European Science Foundation, the European Research Council, participating universities and Accare Centre for Child and Adolescent Psychiatry.

Do not read the stable association as proof that autistic-like features cause functional somatic symptoms, or that functional somatic symptoms cause autistic-like features. The study found no significant wave-to-wave effects, so changes in one did not predict later changes in the other.