From the Journals

Data point to bidirectional link between sleep disorders and ADHD



Insomnia, restless legs syndrome (RLS), and frequent snoring were significantly associated with subsequent ADHD symptoms in a large longitudinal study of adolescents in China.

Investigators twice assessed 7,072 middle and high school students participating in the larger longitudinal Shandong Adolescent Behavior & Health Cohort – in 2015 and 1 year later in 2016 – for sleep, mental health, psychosocial factors (using the self-administered Adolescent Health Questionnaire, or AHQ), and for ADHD symptoms (using the Youth Self-Report, or YSR, of the Achenbach Child Behavior Checklist).

At baseline, ADHD symptoms were reported by 7.6% of adolescents and were significantly correlated, after adjusting for adolescent and family covariates, with all the sleep variables studied: sleep duration of 7 hours or less per night, insomnia symptoms, poor sleep quality, RLS symptoms, frequent snorting, and hypnotic use, reported Xianchen Liu, MD, PhD, of Shandong (China) University, and coinvestigators. They noted a dose-response relationship between sleep duration and the odds of having ADHD symptoms.

At 1-year follow-up, 4.5% of the 6,531 participants who did not have ADHD symptoms at baseline now reported them. After adjustments for covariates, any insomnia (odds ratio, 1.48), difficulty initiating sleep (one of the insomnia symptoms) (OR, 2.09), RLS (OR, 1.47), and frequent snoring (OR, 2.30) at baseline were each significantly associated with development of incident ADHD symptoms and with ADHD severity at 1 year, they reported in Sleep.

“Given the fact that sleep disorders in adolescents are often underdiagnosed and untreated primarily in the primary care setting, our findings highlight that clinicians should assess and manage short sleep duration and sleep problems for effective treatment of ADHD in adolescents,” as well as for prevention, they wrote.

The AHQ includes questions that assess nocturnal sleep duration and sleep problems during the past month. The adolescent and family variables that were selected as covariates and controlled for include cigarette smoking, alcohol drinking, use of mental health services, chronic physical diseases, and parental education and occupation. Depression was also a covariate but was assessed through a different scale.

The YSR measures eight ADHD symptoms during the past 6 months on a 3-point scale (not true, somewhat or sometimes true, and very true or often true). The adolescent participants of this study were in grades 7, 8, and 10 at baseline. Their mean age at baseline was 15 years; half were male. They were part of the larger Shandong Adolescent and Behavioral Cohort, a longitudinal study of almost 12,000 adolescents.

Growing evidence has demonstrated a bidirectional relationship between sleep problems and ADHD symptoms in pediatric populations, the investigators wrote, and further research is needed to examine the “mediators, moderators, and biological mechanisms of the sleep-ADHD link [in adolescents].”

While there are multiple potential pathways for this link, sleep problems may sometimes result in a cluster of behavioral and cognitive symptoms that are not true ADHD but that mimic the disorder, they noted.

The investigators also noted that approximately 67% of adolescents who had clinically relevant ADHD symptoms at baseline no longer had these symptoms at 1-year follow-up – a finding that “supports the [idea]” that ADHD symptoms with onset in adolescence may be transient or episodic rather than persistent.

The study was funded in part by the National Natural Science Foundation of China. The authors reported that they have no conflicts of interest.

SOURCE: Liu X et al. Sleep. 2019 Dec 2. doi: 10.1093/sleep/zsz294.

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