Homotypic and Heterotypic Continuity in Psychiatric Symptoms From Childhood to Adolescence in Autistic Youth.

OBJECTIVE: Despite the high prevalence of mental health difficulties in autistic youth, little is known about the patterns of developmental continuity and change in psychiatric symptoms between childhood and adolescence. Using a stratified community-derived sample of autistic youth (n = 101; 57 males, 44 females), within (homotypic) and between (heterotypic) domain associations between psychiatric symptoms in childhood to adolescence were tested as well as whether any continuities were moderated by sex, IQ, autism symptom severity, social economic status, or parental mental health. METHOD: Autistic youth were assessed for emotional, behavioral, and attention-deficit/hyperactivity disorder (ADHD) symptoms in childhood (age 4-9 years) and adolescence (age 13-17 years) using parental diagnostic interview. Unadjusted and adjusted (accounting for the co-occurrence of psychiatric symptoms in childhood) weighted models tested homotypic and heterotypic associations between symptoms in childhood and adolescence. Moderation of significant pathways was tested using multigroup analysis. RESULTS: Adolescent psychiatric symptoms all were predicted by symptoms of their childhood counterparts (emotional symptoms incidence rate ratio [IRR] = 1.06, 95% CI = 1.02-1.10, p < .01; behavioral symptoms IRR = 1.38, 95% CI = 1.21-1.59, p < .01; ADHD symptoms IRR = 1.11, 95% CI = 1.05-1.19, p < .01); the only heterotypic pathway that remained significant in adjusted analyses was from childhood emotional symptoms to adolescent ADHD symptoms (IRR = 1.04, 95% CI = 1.01-1.07, p = .02). Sex moderated the homotypic ADHD symptoms pathway; associations were significant in female participants only. Child IQ moderated the homotypic behavioral symptoms pathway; the association was stronger in youth with IQ <70. CONCLUSION: Results from this community-based sample suggest that psychiatric symptoms in autistic youth exhibit substantial developmental continuity and thus highlight the importance of early screening and intervention. Sex and IQ may be important factors to consider when predicting likelihood of stability of ADHD and behavioral symptoms.