The impact of affective functions on decision-making behaviour in adult ADHD

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental psychiatric disorder that often persists throughout a patient’s life. ADHD is characterized by a particularly heterogeneous clinical profile, influenced not only by its progression over the years but also by differences between men and women. Deficits in affective functions, which are still rarely considered in adult patients, highlight these gender distinctions as symptoms attributed to emotional processes are more pronounced in female patients. Alongside cognitive functions, these emotional processes are critical in shaping behaviour, particularly in quick and intuitive decision-making and risk-engagement. Emotional arousal, which is coupled with changes in the autonomic nervous system, can modulate and guide unconscious decision-making behaviours. However, the extent to which impairments in decision-making behaviour in adult patients with ADHD depend on this interaction, and whether differences exist between male and female patients in terms of affective symptoms remains largely unexplored. Thus, this thesis aims to investigate the underlying mechanisms of affectively driven decision-making behaviour in adult patients with ADHD compared to healthy controls. Using measurements of physiological changes via skin conductance responses and neural changes via functional MRI, decision-making behaviour was examined in more detail across three consecutive studies. Behavioural data were collected through reaction times in a modified version of the Balloon Analogue Risk Task and self-assessment were gathered using self-report questionnaires that assessed emotional competence, risk attitude, and reward sensitivity. Analyses using a linear mixed-effects model demonstrated that increased risk-taking is not accompanied by an increase in physiological activity in adults with ADHD. Further analyses also revealed that this effect was primarily driven by female patients. Compared to self-reports from questionnaires, an impaired self-perception of one's own behaviour was also demonstrated. Neural correlates further substantiated the connection between physiological response and behaviour, indicating reduced neural activity in the region of the right precuneus and the right superior frontal gyrus in patients with ADHD. Furthermore, hyperactive neural patterns were found in women compared to men within the patient group, emphasizing the critical role of the left insula in emotional processing across genders. Overall, this thesis underscores the significant role of affective processes during decision-making behaviour and highlights gender-specific differences in patients with ADHD. These differences can be attributed to an altered relationship between emotional processing of an event, physiological change and behaviour, primarily related to disturbed interoceptive perception and metacognitive functions. Based on this work, further studies are needed to explore the understanding and gender-specific effects of autonomic nervous system functions in adult ADHD. This could not only deepen our understanding of the behavioural difficulties in adult patients with ADHD but also provide an opportunity for individualized and transdiagnostic treatments.