Dorien Bangma

DECISION-MAKING IN ADHD | 151 reducing deficits in the decision-making process based on the findings of this small number of studies. With regard to controlling for the (long-term) effects of stimulant medication upon performance, the included studies were also shown to differ in their approach. Although the participants in most studies were asked to discontinue medication treatment during testing, the moment of discontinuation varied greatly, from several hours to four days prior to the assessment. It should furthermore be noted that a discontinuation of medication treatment prior to assessment is not necessarily sufficient to control for the long-term effects of ADHD medication. A history of medication use can also have a (positive) effect on the participants’ ability to make decisions, as the medication may have contributed at the time the decision- making abilities were learned/acquired. In four studies, the ADHD participants continued their pharmacological treatment during testing (Gonzalez-Gadea et al., 2013; Mäntylä et al., 2012; Onnink et al., 2015; Yang et al., 2019). This may have led to a reduction in ADHD symptoms in the participant sample (DeVito et al., 2008; Spencer et al., 1995) and consequently to an underestimation of the ADHD related impairments in the decision-making process (e.g., Mäntylä et al., 2012). Of these four studies, only one study controlled for the medication use of the participants (Onnink et al., 2015). Two studies did not specify to what extent the participants were using medication at the time of the assessment (Hurst et al., 2011; Schäfer & Kraneburg, 2015). Underlying mechanisms. According to the dual-pathway model of ADHD, deficits in decision making in individuals with ADHD can be associated with dysregulations of the motivational-emotional and the cognitive pathways in the brain (Sonuga-Barke, 2003, 2005). Motivational-emotional deficits could subsequently lead to problems with intuitive decision- making and cognitive deficits to problems with deliberative decision-making (Mäntylä et al., 2012). Capabilities that are important for deliberative decision-making include knowledge and understanding of probabilities, the ability to update this knowledge in working memory and store it in long-term memory, and the ability to inhibit responses to occasional feedback (Van Duijvenvoorde et al., 2012). Capabilities that are important for intuitive decision-making are the processing of reward and punishment, and the visceral responses to these feedback cues (Dunn et al., 2006; Séguin et al., 2007). Most decision-making tasks included in this review can be seen as a measurement of both intuitive- and deliberative decision-making. However, some decision-making tasks are more specific: some of the included gambling tasks and the sub-tests of the A-DMC battery, e.g., mainly call for deliberative decision making; delay discounting tasks and reward-related tasks, in particular, call for intuitive decision making. In general, it can be concluded that the overall pattern of the findings of the present review (i.e., significant between-group differences in 55% of the studies) is consistent with dual-pathway model of ADHD. In the included studies, adults with ADHD show aberrant performances in both intuitive and deliberative decision-making tasks (Table 6.2). This review therefore provides no evidence that the decision-making deficits found can be explained by purely motivational- emotional or cognitive models. It should however be noted that the suitability of the dual- pathway model of ADHD as an explanatory model for the deficits in the decision making of