Sleep, chronotype and biological rhythms in adults with ADHD: possible clinical correlates

Background: The Attention-Deficit/Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder mostly characterized in childhood for its nuclear symptoms such as inattention, hyperactivity and impulsivity. In the majority of cases ADHD persists in adulthood and is usually characterized by a more complex clinical picture due to the presence of numerous complications and multiple comorbidity. Executive dysfunction and Emotional Dysregulation represent the two fundamental aspects of the disorder in adults, closely related to a top-down dysregulation of non-emotional (i.e., “cold” executive functions) and emotional (i.e., “hot” executive functions) processes, respectively. The heterogeneous clinical picture characterized by forgetfulness, reduced productivity, disorganization, poor management of time, as well as emotional impulsivity, affective instability, delay discounting, risky decision making. Sleep disorders and circadian rhythm abnormalities have been found to frequently associated with adult ADHD and may contribute to the functional impairment caused by the disorder. The aim of this study was to investigate the characteristics related to sleep, chronotype, and biological rhythms in a sample of adults with ADHD. We also explored their associations with "core" features of the disorder, namely inattentive and hyperactive/impulsive symptoms, as well as "accessory" features, such as executive dysfunctions and emotional dysregulation. Methods: A total of 65 adult patients with a clinical diagnosis of ADHD according to the Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5) were enrolled. Sociodemographic characteristics and psychiatric comorbidities were collected. All subjects were evaluated with a set of questionnaires that included the Italian version of the Biological Rhythms Interview of Assessment in Neuropsychiatry (BRIAN) to evaluate the biological rhythms, the Morningness-Eveningness Questionnaire (MEQ) to evaluate the circadian preference, the Insomnia Severity Index (ISI) to evaluate the patient’s perception of insomnia. We used a BRIAN cut-off points > 40 to identify a severe biological rhythm dysregulation. ADHD symptomatology was explored using Adult ADHD Self Report Scale (ASRS) and the Conners’ Adult ADHD Rating Scales–Observer: Short Version (CAARS-O:S). The Behavior Rating Inventory of Executive Function (BRIEF-A) was used to evaluate the executive dysfunctions, and finally the Reactivity Intensity Polarity Stability Questionnaire (RIPoSt-40) was used to measure Emotional Dysregulation. Comparative analyses were conducted to investigate the correlations between sleep, chronotype, biological rhythms and ADHD subtypes and psychiatric comorbidity. Correlation analyses were conducted according to a dimensional approach, in order to evaluate whether core features of adult ADHD (including executive dysfunctions and Emotional Dysregulation) could be specifically associated with biological rhythms disruption, chronotype and insomnia. Results: Overall, 49 patients had significant biological rhythms disruption (75.8%) (BRIAN total score > 40), especially in the subgroup with comorbid cyclothymic disorder. In our sample the intermediate chronotype was the most common. Subjects with ADHD in comorbidity with anxiety disorders significantly correlated with higher scores of biological rhythms alterations (BRIAN total score, p =0.010) and with greater severity of insomnia (ISI total score, p = 0.002). A significant negative correlation was demonstrated between ASRS total score and MEQ total score (p= 0.011, r= -0.31). BRIAN total score was significantly positively associated with Global Executive Composite (r = 0.36, p = 0.003), Behavioral Regulation Index (r = 0.35, p = 0.004), and Metacognition Index (r = 0.35, p = 0.005). Statistically significant positive correlations were also found with the subscales Shift (r = 0.34, p = 0.006), Emotional Control (r = 0.37, p = 0.002), Initiate (r = 0.40, p = 0.001), Working Memory (r = 0.32, p = 0.008), Planning/Organizing (r = 0.33, p = 0.007). Also, BRIAN Eating subscale, BRIAN Sociality subscale and BRIAN Activities subscale were positively associated with BRIEF-A subscales. The severity of ADHD symptoms reported by patients on the ASRS was positively correlated with all BRIAN scales, i.e., with biological rhythms disruption (r = 0.50-0.71, p = 0.001). Significant correlations were also found for ADHD symptoms reported by caregivers with BRIAN total scores and its subscales. Significant positive correlations were observed between all facets of Emotional Dysregulation measured by RIPoSt-40 subscales and BRIAN total score and subscales (r = 0.41-0.59, p= 0.005). The insomnia was correlated significantly with executive dysfunctions, particularly Emotional Control subscale correlated with ISI total score (r= 0.35, p<0.004), with severity subscale (r= 0.35, p< 0.004), with satisfaction subscale (r= 0.33, p< 0.007). Initiate subscale, on the other hand, was positively associated with impact (r = 0.36, p = 0.003) and sleep satisfaction subscales (r = 0.29, p = 0.020). Finally, Plan/Organize subscale was significantly positively associated with impact subscale (r = 0.30, p = 0.016). Conclusions: Chronobiologic and sleep disturbances seems to contribute to the functional disability associated with adult ADHD, including relational, educational, academic, and work-related problems, although the putative mechanisms are not yet clear. They probably contribute to the impairment of motivational and cognitive bias frequently reported in adult ADHD population. For its potential therapeutical implications, the evaluation of the different aspects of circadian rhythmicity, including the sleep/wake pattern, daily activities, social aspects, alimentation and prevalent chronotype should be included in the routinary clinical evaluation of adult ADHD patients. Further research is needed to study the effect of the treatment sleep disorders and re-synchronization of chronobiological rhythms on cognitive and emotional regulation, as well as on ADHD symptomatology