Lai MC, Kassee C, Besney R, et al. - Researchers sought to ascertain the prevalences of co-occurring mental health or psychiatric conditions in people with autism and to identify the moderators so that enhanced recognition and care could be undertaken. Searching MEDLINE, Embase, PsycINFO, Scopus, Web of Science, and grey literature, 9,746 unique studies were identified; of these, 432 were selected for full-text review and 96 were included in this meta-analyses. Observations suggest a higher prevalence of co-occurring mental health conditions in the autism population vs the general population. The meta-analyses revealed overall pooled prevalence estimates of 28% for attention-deficit hyperactivity disorder; 20% for anxiety disorders; 13% for sleep–wake disorders; 12% for disruptive, impulse-control, and conduct disorders; 11% for depressive disorders; 9% (7–10) for obsessive-compulsive disorder; 5% for bipolar disorders; and 4% for schizophrenia spectrum disorders. Heterogeneity in prevalence estimates was identified to be associated with age, gender, intellectual functioning, and country of study.