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Compr Psychiatry. 2007 Nov-Dec;48(6):562-71. Epub 2007 Aug 20.

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

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Mood and Anxiety Division of the Centre for Addiction and Mental Health, Department of Psychiatry, University of Toronto, Toronto, M5T 1R8 Canada.



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.


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.


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.


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.

[Indexed for MEDLINE]

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