Clinical and neuropsychological characterization of emotional dysregulation in adults with and without ADHD: insights from the FEDRA study

Emotional dysregulation (ED) is defined as a failure to regulate emotions, resulting in experiences or expressions that interfere with goal-directed activity. Symptoms of ED, such as extreme mood instability, irritability, and emotional hyper-reactivity, are common among adults diagnosed with attention-deficit/hyperactivity disorder (ADHD). However, a consensus on how to conceptualize this clinically challenging domain within ADHD has yet to be reached. The association between ADHD and ED may reflect a more severe form of ADHD, a distinct subtype, or the co-occurrence of two correlated but separate conditions. This thesis comprises four empirical studies based on data from the FEDRA cohort, a monocentric, cross-sectional investigation designed to examine ED within and beyond ADHD from both clinical and neuropsychological perspectives. The sample included adults diagnosed with ADHD alone, ADHD with co-occurring ED (ADHD+ED), ED associated with psychiatric conditions other than ADHD, and healthy controls (HC). The studies highlighted substantial overlap between ADHD+ED and “pure” ADHD regarding core ADHD symptoms and confirmed a strong association between ADHD and executive dysfunctions, largely independent of ED. Neuropsychological assessment distinguished ADHD participants (with and without ED) from “pure” ED cases and identified a subgroup of ADHD individuals with greater clinical severity and psychosocial impairment, primarily characterized by deficits in response inhibition and attentional processes. High rates of psychiatric comorbidity, particularly mood and anxiety disorders, were observed in both ADHD+ED and “pure” ED, whereas neurodevelopmental and disruptive behavior comorbidities, a poorer course of mood disorders, and more pervasive functional deficits were specific to ADHD+ED participants. Deficits in cognitive flexibility were found in both ADHD+ED and “pure” ED, but group-specific improvements in cognitive flexibility when processing emotional stimuli were observed in individuals with “pure” ED. Overall, the results support the conceptualization of ED as an independent condition or specifier that co-occurs with ADHD and other psychiatric disorders. ADHD was primarily associated with core symptoms and neuropsychological impairments, whereas ED was linked to negative emotionality, mood and anxiety disorders, and reduced cognitive flexibility. While participants with ADHD+ED exhibited a combination of these characteristics, synergistic effects may account for the heightened disruptive comorbidity, poorer course of mood disorders, and pervasive functional impairments. These findings have important implications for diagnosis, clinical assessment, and treatment planning. They underscore the importance of identifying ED in individuals with ADHD, confirm the applicability of ED criteria across diagnoses, and highlight the need for further research comparing populations with and without ED to evaluate its transdiagnostic relevance. Indicators such as a history of neurodevelopmental disorders, disruptive behaviors, early-onset recurrent mood episodes, and neuropsychological or functional impairments may aid the differential diagnosis of ADHD when ED is present. From a therapeutic perspective, interventions for patients with ADHD and ED should address both the core symptoms of ADHD and executive dysfunctions, as well as ED and its associated comorbidities, given the potential synergistic impact of these conditions on the course of illness and functional outcomes.