Predictive value of subclinical autistic traits at age 14-15 months for behavioural and cognitive problems at age 3-5 years.

It is unclear whether subclinical autistic traits at very young age are transient or stable, and have clinical relevance. This study investigated the relationship between early subclinical autistic traits and the occurrence of later developmental and behavioural problems as well as problems in cognitive and language functioning. Parents of infants aged 14-15 months from the general population completed the Early Screening of Autistic Traits Questionnaire (ESAT). Three groups of children with high, moderate, and low ESAT-scores (total n = 103) were selected. Follow-up assessments included the CBCL 1(1/2)-5 at age 3 years, and the SCQ, the ADI-R, the ADOS-G, an on-verbal intelligence test, and language tests for comprehension and production at age 4-5 years. None of the children met criteria for autism spectrum disorder at follow-up. Children with high ESAT-scores at 14-15 months showed significantly more internalizing and externalizing problems at age 3 years and scored significantly lower on language tests at age 4-5 years than children with moderate or low ESAT-scores. Further, significantly more children with high ESAT-scores (14/26, 53.8%) than with moderate and low ESAT-scores (5/36, 13.9% and 1/41, 2.4%, respectively) were in the high-risk/clinical range on one or more outcome domains (autistic symptoms, behavioural problems, cognitive and language abilities). Subclinical autistic traits at 14-15 months predict later behavioural problems and delays in cognitive and language functioning rather than later ASD-diagnoses. The theoretical implications of the findings lie in the pivotal role of early social and communication skills for the development of self-regulation of emotions and impulses. The practical implications bear on the early recognition of children at risk for behavioural problems and for language and cognitive problems.