Seasonality and circadian preference in adult attention-deficit/hyperactivity disorder: clinical and neuropsychological correlates

OBJECTIVE: The objective of the study was to measure both seasonal mood change and circadian preference, and their clinical and neuropsychological correlates, in adults with ADHD during the fall/winter months. METHOD: Twenty-nine adults with attention-deficit/hyperactivity disorder (ADHD) were assessed in the fall/winter season using self-report measures of ADHD, mood, seasonality, and circadian preference. Neuropsychological tests were also completed. Correlations between chronobiologic variables and clinical/neuropsychological measures were performed. RESULTS: Consistent with prior work in adult ADHD, high rates of seasonal depression were reported in this sample. Based on the morningness-eveningness questionnaire, which assesses circadian preference 11 (40.7%, N = 27) subjects were designated as evening types and only 5 (18.5%) as morning types, a distribution highly discrepant with general population studies. Later circadian preference, independent of seasonality, was strongly correlated with both self-reported symptoms of ADHD and neuropsychological deficits, including impulsive responding and poor target discrimination. None of these findings was attributable to state depression. CONCLUSIONS: In the fall/winter period, a mood-independent delay in circadian phase may contribute significantly to core pathology in many adults with ADHD. These findings establish a potential target for chronobiologic treatments such as light therapy in this complex population.