This study aimed to characterize the rates and types of diagnosed mental health (MH) disorders among children and adolescents before and during foster care (FC) overall and by race and ethnicity.

We used population-based linked administrative data of medical assistance (public insurance) claims records and child protective services data from a cohort of early adolescents who entered FC at 10 to 14 years old. MH diagnoses were coded according to the International Classification of Diseases, Ninth and Tenth Revisions, Clinical Modification (ICD-9 and ICD-10) and included adjustment disorders, disruptive disorders, attention-deficit/hyperactivity disorder (ADHD), anxiety disorders, mood disorders, attachment disorders, autism, and other disorders.

Before FC entry, 41% of children and adolescents had at least 1 MH diagnosis. Attention-deficit/hyperactivity disorder (25%), mood disorders (18%), and disruptive disorders (15%) were the most common pre-entry diagnoses. Among early adolescents entering FC with no previous diagnosis, 52% were later diagnosed with adjustment disorder (accounting for 73% of all youth with a new diagnosis during FC). White early adolescents had higher rates of diagnosed MH disorders before FC, whereas racial/ethnic minority early adolescents were more likely to receive a MH diagnosis during FC. Black early adolescents were more likely than White and Hispanic early adolescents to be diagnosed with disruptive disorders and less likely to be diagnosed with anxiety or adjustment disorders during FC.

Results highlight the high rates of MH needs among early adolescents before entry into FC, whether detected before or during FC. Results also illustrate disparities in pre-entry MH care between racial/ethnic minority and White early adolescents, with minority youth less likely to be receiving services before entry.