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Take special care when diagnosing late-onset ADHD

Recent findings suggest that although late-onset ADHD is a valid diagnosis, many individuals seeking treatment are experiencing nonimpairing cognitive fluctuations, a comorbid disorder or cognitive effects of substance use.

“Adolescents and young adults without childhood ADHD often present to clinics seeking stimulant medication for late-onset ADHD symptoms. Recent birth-cohort studies support the notion of late-onset ADHD, but these investigations are limited by relying on screening instruments to assess ADHD, not considering alternative causes of symptoms, or failing to obtain complete psychiatric histories,” Margaret H. Sibley, PhD, of Florida International University, Miami, and colleagues wrote.

To address these limitations, researchers analyzed psychiatric assessments administered longitudinally to local normative participants in the Multimodal Treatment Study of ADHD. Study participants without ADHD (n = 239) completed eight assessments from comparison baseline at a mean age of 9.89 years to young adulthood at a mean age of 24.4 years. Parent, teacher and self-reports of ADHD symptoms, impairment, substance use and other mental disorders were utilized.

The majority of participants who initially screened positive on symptom checklists were excluded from late-onset ADHD diagnosis.

Among participants with impairing late-onset ADHD symptoms, the most common reason for diagnostic exclusion was symptoms or impairment associated exclusively with heavy substance use.

Most participants with late-onset symptoms displayed onset in adolescence and had an adolescence-limited presentation.

Researchers found no evidence for adult-onset ADHD independent of a complex psychiatric history.

“Some adolescents and young adults who present for first-time ADHD diagnoses may represent valid late-onset cases. However, the most common source of impairing late-onset ADHD symptoms in adolescence and young adulthood was substance use,” the researchers wrote. “Prior to diagnosing or treating ADHD in late-onset cases, clinicians should carefully assess and treat substance use and comorbid mental health disorders as a potential source of symptoms. The majority of adolescent-onset cases possessed transient symptoms. Thus, it may be appropriate to give provisional first-time ADHD diagnoses in adolescence and to monitor symptoms over time, as remission may occur within a few years.” – by Amanda Oldt

Disclosures: Sibley reports receiving book royalties from Guilford Press. Please see the study for all other authors’ relevant financial disclosures.