The role of circadian rhythms in individuals with attention deficit hyperactivity disorder and obesity: A narrative review

Background. A relationship between attention deficit hyperactivity disorder (ADHD) and obesity has been consistently documented. Obesity and metabolic syndrome have been associated with misalignment between daily activities and circadian rhythm. ADHD patients have a high prevalence of delayed sleep phase syndrome, which is a circadian rhythm disorder. Understanding this relationship is important for the evaluation of obese population at risk. Objective. The aim of this narrative review was to summarize the information updated until 2019 about the role of circadian rhythms in obese ADHD individuals. Method. A search was performed in MEDLINE, EMBASE, and Google Scholar database. The terms ADHD, obesity, circadian rhythm, sleep disorders, adolescent, adult, Adolesc, circadian, attention deficit hyperactivity disorder, and child were combined with logical functions. Results. A total of 132 articles were reviewed. Evidence showed that ADHD subjects have an increased risk to present obesity and circadian rhythms disorders. Some possible pathways for this relationship have been hypothesized including obesity as a risk factor, an underpinned common biological dysfunction, and behavioral and cognitive features of individuals with ADHD. As most of the articles are methodologically cross-sectional, it is not possible to establish causative associations. Discussion and conclusion. This review points out the importance of early recognizing and treating circadian rhythms disorders and obesity in ADHD patients. Future studies must be carried out with a longitudinal design to establish the effect of each comorbidity in the treatment of individuals with ADHD.