Abstract
BACKGROUND: Amphetamine use disorder (AMPH) and attention deficit-hyperactivity disorder (ADHD) often co-occur and are associated with poor treatment outcomes. Elevated impulsivity is a core feature in both disorders. Little is known however about the specific neurocognitive profile regarding different facets of impulsivity, and specifically impulsive choice, in comorbid populations. METHODS: Three groups (ADHD + AMPH, ADHD only and healthy controls (HC)) were assessed with self-reported impulsivity and cognitive tasks of impulsive choice, operationalized as delay aversion (DA) and reflection impulsivity. RESULTS: Twenty-nine participants with comorbid ADHD + AMPH, 25 participants with ADHD only and 116 HC completed screening, including self-rating scales, and cognitive testing. 20, 16 and 114 participants completed computerized cognitive tasks in the ADHD + AMPH group, ADHD group and HC group, respectively. The ADHD + AMPH group reported significantly higher motor, attentional and non-planning impulsiveness, and showed a significantly higher degree of impulsive choice, compared to both groups. There were no differences in task-related impulsiveness between ADHD only and HC. CONCLUSIONS: The current findings suggest that individuals with ADHD + AMPH have overall elevated levels of impulsivity compared to individuals with ADHD only. In addition, that ADHD + AMPH is specifically associated with impairments in task-related impulsive choice, which was not found in ADHD only compared to HC. The neurocognitive profile in this specific patient group may represent a need for more systematic screening within healthcare settings in order to develop effective and targeted treatment for comorbid patients. TRIAL REGISTRATION: EudraCT, 2012-004298-20.