Dorien Bangma

DECISION-MAKING IN ADHD | 149 Discussion The aim of this systematic review was to determine the nature and extent of potential deficits in the decision making of adults with ADHD. Given that ADHD and the associated impairments have only been studied extensively in adults from the 1990s and onwards (Lange et al., 2010), only a limited number of studies were found within the search parameters. In total, 31 studies that examined the performances of adults with ADHD in different types of decision-making tasks were included. Of these studies, 55% reported that adults with ADHD displayed aberrant behavior on one or more of the decision-making tasks at hand, as was indicated by significant group differences between the ADHD and control groups. This review therefore cautiously provides evidence of differences in the decision making of healthy individuals and adults with ADHD. However, the findings are highly inconsistent. Various factors that could influence the outcome of decision-making tasks, including the variety of decision-making domains that have been examined, the high level of comorbidity, and the use of medication in the ADHD groups, may explain this inconsistency. Domains of decision making. A prominent finding of this review is that measures of risky decision-making (i.e., gambling tasks) appear to be largely overrepresented in the current evidence base as compared to other decision-making domains (Table 6.2). This may be due to the large availability of performance-based tasks that measure risky decision making as compared to the availability of other types of decision-making tasks (Table 6.1). Another explanation may be the appeal of risky decision-making in adults with ADHD as a topic for research. Risky decision-making has both been well established in children and adolescents with ADHD, and is clearly documented in real-life scenarios (e.g., Groen et al., 2013; Pollak et al., 2016). The consequences of increased risk-taking in adults with ADHD have been frequently described in terms of a higher risk of substance abuse (Charach et al., 2011), criminal behavior (Fletcher & Wolfe, 2009), unsafe sex (Sarver et al., 2014) and dangerous driving (Fuermaier et al., 2017) in this population. Contrary to what has been established in children with ADHD, and in the daily life of adults with ADHD, only a minority of studies (i.e., 45%) found that adults with ADHD performed in a more risky fashion than the control groups on the adopted tasks. With the previous results of Groen et al. (2013) in mind, this finding is not surprising (see also Mowinckel et al., 2015). Groen et al. (2013) argue that the developmental trajectory of ADHD, which is characterized by a reduction in ADHD symptoms from childhood to adulthood, could make risky decision-making less prominent in adults with ADHD than in children. Moreover, the experimental gambling tasks that have been used in the included studies, may not form a truly valid model for risk-taking behavior in daily life. According to Pollak et al. (2018), this lack of ecological validity may explain the gap between real-life risk- taking and experimental behavior (see also ‘limitations and future directions for research’). Given the prominent role of delay discounting in theories about the underlying mechanisms of ADHD (e.g., Sonuga-Barke, 2003, 2005) and the clear deficits found in children and adolescents with ADHD regarding this decision-making domain (Mies et al., 2019; Patros et al., 2016; Sonuga‐Barke et al., 1992), the inconsistency in the results of studies that looked at delay discounting in adults with ADHD is more surprising. Mowinckel et al. (2015)