Prospective, longitudinal study of tic, obsessive-compulsive, and attention-deficit/hyperactivity disorders in an...

Understanding the interrelatedness of tics, obsessive-compulsive disorder (OCD), and attention-deficit/hyperactivity disorder (ADHD) has been complicated by studying only cross-sectional samples of clinically referred subjects. The authors report the cross-sectional and longitudinal associations of these disorders in an epidemiological sample of children followed prospectively into early adulthood.

Structured diagnostic interview information was acquired on 976 children, aged 1 to 10 years, who were randomly selected from families living in upstate New York in 1975. Reassessments were acquired in 776 of these subjects 8, 10, and 15 years later. Diagnostic prevalences were estimated at each time point. The associations among tics, OCD, and ADHD were assessed within and across time points, as were their associations with comorbid illnesses and demographic risk factors.

In temporal cross-section, tics and ADHD symptoms were associated with OCD symptoms in late adolescence and early adulthood after demographic features and comorbid psychiatric symptoms were controlled. In prospective analyses, tics in childhood and early adolescence predicted an increase in OCD symptoms in late adolescence and early adulthood. ADHD symptoms in adolescence predicted more OCD symptoms in early adulthood, and OCD in adolescence predicted more ADHD symptoms in adulthood. The associations of tics with ADHD were unimpressive in temporal cross-section and were not significant in prospective analyses. Tics, OCD, and ADHD shared numerous complex associations with demographic and psychopathological risk factors. ADHD was associated with lower IQ and lower social status, whereas OCD was associated with higher IQ.

Tics and OCD were significantly associated in this sample, as were OCD and ADHD. These findings are in general consistent with those from family studies, and they help to define the natural history, comorbid illnesses, and interrelatedness of these conditions.