Predicting engagement in working memory training for methamphetamine use disorder: indices of motivation, attention, and achievement

Rationale: Impulsivity and inefficient self-regulation are major deficits in substance use disorder, corresponding to lack of treatment response and low abstinence rates. Prefrontal cortex (PFC) executive functions, such as working memory (WM), enable self-regulation of impulsivity by keeping in mind cognitive strategies for optimal decisions about future action. Training WM may improve self-regulation of impulsivity in various populations, including methamphetamine use disorder (MUD) patients. However, many controversies exist regarding the efficacy of WM training (e.g. near- versus far-transfer effects) and associated improvements to clinical outcomes. Such controversies may relate, as observed in our preliminary study in MUD patients, to variation in WM training engagement. Methods: In this nested examination of n=17 male MUD patient data (age range 20-39 yrs) from a previously published study, the primary aim was to identify variables that may predict a WM training engagement index (EI), and secondarily to determine if EI could predict clinical improvement in MUD patients. The EI consisted of three domains of WM training: motivation, attention/learning and achievement, and we examined the link between self-report measures of impulsivity, self-regulation, anxiety/depression and executive function and EI. Results: Those with higher rates of attention/learning demonstrated greater improvement in attentional impulsivity, and those with higher rates of achievement had a significant improvement in self-reported anxiety, as well as slower time to complete an executive function task after treatment. Discussion: We suggest the EI is a useful measure to detect level of engagement during WM training in patients with MUD, and is predictive of clinical improvements.