ADHD in narcolepsy: A closer look at prevalence and ties

The reported prevalence of attention deficit hyperactivity disorder (ADHD) in narcolepsy varies considerably, while the associated factors remain inadequately established. A systematic search of studies published in PubMed, EMBASE, and the Cochrane Library was performed from inception to March 2023. Ten studies with 839 patients with narcolepsy were included in the study. Utilizing a random effects model, the pooled prevalence of ADHD in narcolepsy was 25% (95% CI, 14-38%). Notably, patients with narcolepsy type 2 showed a significantly higher prevalence of ADHD than that of narcolepsy type 1 (46% vs. 20%, p = 0.045). Furthermore, the rate of ADHD was notably elevated in narcolepsy compared with the healthy controls (odds ratio 9.59, 95% CI, 4.06-22.63, p < 0.001). Several factors such as excessive daytime sleepiness (EDS), fatigue, insomnia severity, and the quality of life were significantly associated with ADHD in narcolepsy (all ps < 0.05). These findings highlight the importance of monitoring and managing ADHD in narcolepsy, and provide a clue to help reducing ADHD by intervening in these associated factors.