0814 Light Regularity Associated with Cognitive Performance in Adolescents with ADHD

Abstract Introduction Regular light exposure may play a key role in cognitive performance via both direct (via arousal) and indirect (via circadian rhythm regulation) mechanisms. Adolescents with ADHD are at risk for both cognitive deficits and circadian dysregulation, including delayed and irregular sleep patterns, and light exposure has been proposed as a critical contributor to ADHD-related impairments via its influence on circadian rhythm regulation. However, whether light irregularity contributes to cognitive impairment in adolescents with ADHD, and whether such relationships are mediated by disrupted sleep patterns, is unknown. Methods Forty-six adolescents aged 13-17 (54% female) completed a diagnostic interview, 5 days/nights of actigraphy, and a cognitive measure (Kaufman Brief Intelligence Test-Second Edition (KBIT-2): Verbal, Nonverbal, and Composite scores). Twenty were diagnosed with ADHD; 26 were healthy controls (HC). Partial Pearson correlations covarying for sex and age examined associations between the light regularity index (LRI: derived from actigraph-measured light exposure) and KBIT-2 performance in the full sample. We further explored whether LRI-cognition associations were specific to the ADHD group, and if so, whether such relationships were explained by shorter (total sleep time, TST), less regular (sleep regularity index, SRI), and delayed (sleep midpoint) sleep patterns. Results In the full sample, lower LRI correlated with poorer composite (r=.34, p=.03) and verbal (r=.42,p=.005), but not nonverbal (r=.08, p=.62), cognitive performance. Adolescents with ADHD displayed lower LRI than HC (β=-.31), and decreased LRI was related to lower SRI (r=.63) and later sleep midpoint (r=-.50) in this group (p’s.05). In the ADHD group, LRI was associated with composite (r=.67) and verbal (r=.70) cognitive performance (p’s.01), and these relationships remained significant in sensitivity analyses controlling for SRI, TST, and sleep midpoint (p’s.05). Associations between LRI and cognition were non-significant in HC (p’s.10). Conclusion Irregular light exposure is associated with cognitive deficits among adolescents with ADHD, which is not fully explained by disrupted actigraphy-measured sleep patterns. Future studies using additional behavioral and biological measures of circadian function (e.g., Dim Light Melatonin Onset) may elucidate the specific mechanisms by which light regularity supports cognitive performance among adolescents with ADHD and assess whether regularly-timed light exposure chronotherapy improves cognition in this population. Support (if any) K23MH108704, R34MH128440