ADHD, circadian rhythms and seasonality.

Area of Science:

• Neuroscience
• Psychiatry
• Chronobiology

Background:

• Adult Attention-Deficit/Hyperactivity Disorder (ADHD) and Seasonal Affective Disorder (SAD) are prevalent conditions.
• Circadian rhythm disturbances are common in both ADHD and SAD.
• The mediating role of circadian rhythm in the ADHD-SAD association requires further investigation.

Purpose of the Study:

• To investigate whether the association between adult ADHD and SAD is mediated by circadian rhythm.
• To determine the prevalence of SAD in individuals with and without ADHD symptoms.
• To identify specific sleep parameters that may link ADHD and SAD.

Main Methods:

• Utilized data from the Netherlands Study of Depression and Anxiety (NESDA) cohort (N=2239).
• Compared individuals with clinically significant ADHD symptoms (N=175) to those without (N=2064).
• Assessed ADHD symptoms using the Conners Adult ADHD Rating Scale and SAD prevalence with the Seasonal Pattern Assessment Questionnaire (SPAQ).
• Collected sleep data, including sleep onset and offset times, using the Munich Chronotype Questionnaire.

Main Results:

• The prevalence of probable SAD was significantly higher in the ADHD group (9.9%) compared to the no ADHD group (3.3%).
• Subsyndromal SAD (s-SAD) was also more prevalent in the ADHD group (12.5% vs. 4.6%).
• Late self-reported sleep onset significantly mediated the relationship between ADHD symptoms and probable SAD, even after adjusting for confounders.

Conclusions:

• Circadian rhythm disturbances, particularly delayed sleep onset, are significantly associated with ADHD symptoms.
• Delayed sleep onset may contribute to the increased prevalence of SAD symptoms in individuals with ADHD.
• Considering ADHD and delayed sleep onset in SAD patients could improve treatment outcomes.