How does methamphetamine affect the brain? A systematic review of magnetic resonance imaging studies

Methamphetamine (METH) is an addictive psychostimulant that is associated with significant physical and psychological harm. Magnetic resonance imaging (MRI) is a non-invasive and powerful imaging modality that can reveal structural and functional brain changes. We conducted a systematic review to identify and appraise the existing literature examining brain MRI changes associated with METH exposure. A comprehensive literature search was conducted on PubMed, Web of Science, and Scopus. Any study that used MRI to evaluate brain changes in people who used or had been exposed to METH using MRI were included. Data were collected on study design, participant demographics, METH use parameters, MRI acquisition details, and key findings. Quality appraisal was conducted using an a priori quality appraisal tool. One hundred and thirty seven studies with 8313 participants were included in our review. Nearly all were conducted in adults/adolescents (121/137, 88%), and most studies were cross-sectional (107/137, 78%). Task-based functional MRI was the most common modality used (48/137, 35%), followed by structural MRI (38/137, 28%). Quality appraisal scores ranged from 40 – 100% (mean 88%). Overall, METH is associated with numerous adverse changes in brain structure and function, including reduced grey matter volume and thickness in frontal and limbic regions and decreased fractional anisotropy in various white matter structures, with associated socio-emotional dysregulation, impaired decision-making and learning processes, and cognitive deficits. Targeted, higher-order, or multi-modal MRI sequences may be useful in further clarifying the impact of METH on the brain and evaluating the use of potential therapeutic agents.