Children who fail to meet existing diagnostic thresholds for attention-deficit/hyperactivity disorder (ADHD) may still exhibit clinical features of the disease, according to research published in the Journal of Clinical Psychiatry.

Researchers derived diagnostic data on patients with subthreshold and full ADHD using consecutive referrals (n=2947) to a pediatric psychopharmacology program. Healthy controls were identified from similarly designed longitudinal studies. Qualified psychometricians conducted psychiatric assessments of patients with full or subthreshold ADHD using the Schedule for Affective Disorders and Schizophrenia for School-Age Children – Epidemiologic Version. The study also captured psychopathology, anxiety and depressive symptoms, social functioning, and cognitive ability among participants. Parents provided information regarding their child’s history of problems in school, including grade retention and placement in remedial classes. Additional sociodemographic factors, including family functioning, pregnancy history, and economic status, were assessed.

Children were diagnosed with subthreshold ADHD if they met at least one of the following criteria: age of onset for ADHD was ≥7 years and/or they had an insufficient number of ADHD inattentive or hyperactive/impulsive symptoms per the Diagnostic and Statistical Manual of Mental Disorders-III-R or Diagnostic and Statistical Manual of Mental Disorders-IV criteria. Among the 1931 participants diagnosed with ADHD, 140 (7%) were diagnosed with subthreshold ADHD. Of these, 48% had an age of onset ≥7 years and 73% had insufficient symptoms. Compared with healthy controls, those with subthreshold ADHD had a higher mean number of comorbid disorders, including mood, anxiety, and elimination disorders (P <.001 for all) and substance use disorders (P <.05). Compared with controls, those with subthreshold ADHD also experienced greater impairments in social functioning (P <.001) and had higher rates of requiring extra help in school or being placed in a special class (P <.001). Both those with subthreshold and full ADHD had worse Global Assessment of Functioning scores compared with controls (P <.001). However, compared to those with full ADHD, subjects with subthreshold ADHD experienced fewer perinatal complications, had better family functioning scores, were more likely to be girls (P <.001), and were more likely to be of a higher socioeconomic status (P <.001).

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These data suggest that subthreshold ADHD is associated with significant morbidity and disability and emphasize the necessity of support for children who fail to meet the diagnostic criteria for full ADHD.

Disclosures: Please see reference for a full list of disclosures.


Biederman J, Fitzgerald M, Kirova A-M, Woodworth KY, Biederman I, Faraone SV. Further evidence of morbidity and dysfunction associated with subsyndromal ADHD in clinically referred children. J Clin Psychiatry. 2018;79(5):17m11870.