Abstract
ADHD is a neurodevelopmental disorder with a long trajectory into adulthood where it is often comorbid with depression, substance use disorder (SUD) or obesity. Previous studies described a dysregulated dopaminergic system, reflected by abnormal reward processing, both in ADHD as well as in depression, SUD or obesity. No study so far however tested systematically whether pathologies in the brain’s reward system explain the frequent comorbidity in adult ADHD. To test this, we acquired MRI scans from 137 participants probing the reward system by a monetary incentive delay task (MIDT) as well as assessing resting-state connectivity with ventral striatum as a seed mask. No differences were found between comorbid disorders, but a significant linear effect pointed toward less left intrastriatal connectivity in patients depending on the number of comorbidities. This points towards a neurobiologically impaired reward- and decision-making ability in patients with more comorbid disorders. This suggests that less intrastriatal connectivity parallels disorder severity but not disorder specificity, while MIDT abnormalities seem mainly to be driven by ADHD.
Highlights
attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder, primarily characterized by inattentiveness, impulsiveness and hyperactivity [1]
In the current study, we investigate the reward network in subjects suffering from ADHD and various comorbid disorders where alterations in the reward network have been suggested to play a role, namely major depressive disorder (MDD), substance use disorder (SUD), and obesity
We extracted the mean beta from the accumbens-ROI-mask and correlated it to global assessment of functioning (GAF) and clinical global impression (CGI) in n = 51 patients
Summary
ADHD is a neurodevelopmental disorder, primarily characterized by inattentiveness, impulsiveness and hyperactivity [1]. Prevalence in children is between 5 and 7% world wide, with a high persistence into adulthood [1]. A high number of childhood patients report persistent symptoms and impairment in adulthood, leading to prevalence ranges between 2.5 and 3% in adults [2,3,4]. Apart from impairment due to ADHD symptoms, patients have an increased chance of developing comorbid psychiatric disorders over the lifespan. Personality disorders, and substance use disorders (SUD) are all significantly more prevalent in patients with ADHD as compared to the general population [5,6,7]. Patients suffering from ADHD and comorbid disorders report higher disease burden [5] and decreased treatment efficacy [8], underlining the need for more research into the underlying mechanisms resulting in this high comorbidity for subjects with ADHD
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