return to TMARC

Publication Abstract Display
Type: Published Abstract
Title: Risky decision making in methamphetamine dependent adults with ADHD.
Authors: Duarte N, Woods SP, Rooney A, Riggs PK, Atkinson JH, Grant I, and the HNRP Group
Year: 2011
Publication: American Psychological Association 119th Convention, Washington, D.C., August 4-7
Volume: Issue: Pages:
Abstract:INTRODUCTION: Methamphetamine (MA) use is associated with dysregulation of prefrontal systems, including deficits in executive functions and working memory. Individuals with MA use disorders demonstrate risky decision-making, whereby the individual selects high immediate gains that ultimately yield greater future losses. MA dependent individuals exhibit decreased activation of the prefrontal cortex during decision making. It is postulated that risky decision-making may be driven by deficits in working memory that impair the development and application of effective, strategic reasoning. Comorbid Attention-Deficit/Hyperactivity Disorder (ADHD), which is associated with prefrontostriatal dysregulation and working memory deficits, may therefore exacerbate risky decision-making in MA users. Approximately 40% of MA users have a lifetime history of ADHD, which may increase the risk of MA-associated neurocognitive deficits, especially in executive function and working memory. Individuals with ADHD also demonstrate risky decision-making, but no prior studies have examined the effects of comorbid ADHD on decision-making in MA dependence. As such, given the theoretical associations between working memory, decision-making, and prefrontal systems, the current study evaluated the hypothesis that working memory deficits would interact with a comorbid ADHD diagnosis to amplify risky decision-making in MA users. METHOD: 48 outpatient MA dependent individuals were classified as either ADHD- (ADHD-MA+; n = 23) or ADHD+ (ADHD+MA+; n = 25) using a structured interview for DSM-IV diagnoses. These two groups were hand matched on relevant demographic characteristics and compared to 22 healthy adults (ADHD-MA-). Participants were classified as MA+ if they met lifetime DSM-IV criteria for MA dependence and also criteria for a MA use diagnosis (abuse or dependence) within 18 months of assessment. Participants were classified as MA- if they never met criteria for a MA use disorder (abuse or dependence). Individuals with histories of psychosis or neurological disease (e.g., seizure disorders) were excluded. Participants who met criteria for dependence for substances other than MA (e.g., cocaine) within the last five years, or who met criteria for substance abuse within the last year (with the exception of MA, alcohol, and cannabis), were also excluded. Participants completed the computerized version of the Iowa Gambling Task (IGT; Bechara et al., 2000). The IGT is a computerized task in which participants select cards from four decks, which vary in outcome; two decks contain choices that are advantageous choices (decks C and D) and two decks contain choices that are disadvantageous (decks A and B). The task consists of 100 trials and in each trial the participant may win or lose a certain amount of money based on which deck they select. Trials are divided into five blocks with 20 choices in each block. The participant''''s total net score (i.e. the total number of advantageous choices minus the total number of disadvantageous choices across all five blocks) was used as a measure of decision making. Risky decision making was defined as an affinity for choosing from decks that produce disadvantageous outcomes (i.e. decks A and B). In addition to the IGT task, participants completed a full neuropsychological test battery to measure neurocognitive performance across a wide range of domains, including working memory. The working memory domain was operationalized using two neurocognitive tests, the Spatial Span subtest of the WMS-III and the Paced Auditory Serial-Addition Task (PASAT). Raw scores were converted to demographically-adjusted T-scores, which were transformed into Heaton deficit scores (range 0-5) that were averaged to derive a working memory domain deficit score. A cut-point of > 0.5 was used to classify impairment. RESULTS: Analysis of variance showed a main effect of group status (F(2, 64) = 6.24, p < .05) such that the ADHD+MA+ group was significantly more likely to make more total (i.e. across all five trials) disadvantageous choices (Mean = 52.5, SD = 9.2) on the IGT than the ADHD-MA+ (Mean = 46.1, SD = 11.9) and ADHD-MA- (Mean = 45.2, SD = 11.4) groups (p < .05). Specifically, the ADHD+MA+ group was significantly more likely to make disadvantageous choices on trials 3 and 5 than the ADHD-MA+ and the ADHD-MA- groups (p < .05). The main effect of working memory was not significant (F(2, 64) = 0.88; p > .05); however, we observed a significant two-way interaction effect (F(2, 64) = 3.42; p < .05), whereby the ADHD+MA+ participants who were working memory impaired were significantly more likely to make disadvantageous choices than all other study groups (ps < .05). Follow-up multiple regression analyses showed that these findings were not better explained by comorbid lifetime DSM-IV diagnoses of major depression or non-MA substance use disorders. DISCUSSION: Results from this study add to the growing body of literature showing that comorbid ADHD may play an important role in the expression of neurocognitive deficits in MA users. Specifically, ADHD+MA+ participants with impaired working memory are significantly more likely to engage in risky decision making, demonstrating a tendency to make high immediate value choices that lead to disadvantageous outcomes. Results point to impaired working memory as the underlying mechanism that drives risky decision making in MA users with comorbid ADHD. These findings suggest that MA users with comorbid ADHD diagnoses, in particular those individuals who also exhibit impairment in working memory, are more likely to make risky decisions; thus these individuals may be more likely to engage in particular behaviors (e.g., sharing needles, engaging in unprotected sex), that place them at increase the risk for negative health outcomes, including HIV and HCV transmission. The current study was limited due to the lack of a non-MA using ADHD comparison group (i.e. ADHD+MA-); future studies should aim to include ADHD+MA- cohorts in an effort better examine the unique and/or interactive effect that an ADHD diagnosis has on decision-making. Future studies that utilize imaging techniques are also warranted to confirm the involvement of frontal systems in decision making processes.

return to publications listing