Methamphetamine-related working memory difficulties underpinned by reduced frontoparietal responses

Area of Science:

• Neuroscience
• Cognitive Psychology
• Addiction Research

Background:

• Working memory deficits are prevalent and debilitating in individuals with problematic methamphetamine use (MA+).
• Neural underpinnings of these working memory difficulties in MA+ individuals remain poorly understood.
• Understanding these neural dysfunctions is crucial for developing effective interventions and supporting recovery.

Purpose of the Study:

• To investigate the neural dysfunctions associated with working memory difficulties in individuals with problematic methamphetamine use.
• To compare brain activity during a working memory task between MA+ individuals and controls (MA-).
• To explore the relationship between neural activity patterns and working memory performance in MA+ individuals.

Main Methods:

• Cross-sectional functional magnetic resonance imaging (fMRI) study.
• Participants included individuals with problematic methamphetamine use (MA+, n=65) and controls (MA-, n=44).
• A parametric n-back task (0-back to 2-back) was administered during fMRI, alongside out-of-scanner cognitive assessments.

Main Results:

• MA+ participants demonstrated significantly lower working memory ability compared to MA- participants.
• fMRI revealed altered load-induced brain activation patterns in MA+ individuals, particularly in frontoparietal and default-mode networks.
• MA+ participants showed attenuated activation increases in frontoparietal areas and decreases in default-mode areas with increasing task load.
• Increased frontoparietal activation from 0-back to 2-back correlated with better working memory ability in MA+ individuals.

Conclusions:

• Problematic methamphetamine use is associated with reduced working memory ability and distinct patterns of neural dysfunction.
• Load-induced alterations in frontoparietal and default-mode areas represent potential neural correlates of working memory deficits in MA+ individuals.
• Frontoparietal network activity during working memory tasks may serve as a neural signature for individual differences in working memory capacity among those with chronic methamphetamine use.