Methamphetamine use has spread in many European countries and the United States. The current review provides a summary and critical analysis of research on cognitive deficits associated with methamphetamine, also known as “crystal meth.” The literature search performed for this review led us to the hypothesis that methamphetamine use is associated with persistent changes in brain metabolism that result in various impairments, such as deficits in memory, attention, and concentration. The dopaminergic system in particular seems to be affected. Some studies indicate that cognitive impairments may improve when users become abstinent, but results of other studies are conflicting. This review discusses these findings and the consequences for the development of a specific addiction treatment for methamphetamine.

Background: Stimulant drugs can cause persistent changes in the brain. Imaging studies show that these changes are most apparent in dopamine transporter (DAT) or receptor availability within the striatum.Methods: This work focuses on influences of stimulant use on dopaminergic function assessed using nuclear-medicine imaging (PET/SPECT). Included are 39 studies on 655 cocaine, amphetamine, methamphetamine or nicotine users, as well as 690 healthy controls. Metaanalyses were conducted separately for D2/D3 receptors and dopamine transporters of the entire striatum, its subregions caudate and putamen respectively.Results: Meta-analyses results regarding nicotine did not show significant effects between smokers and nonsmokers. In cocaine users there was a significant decrease in dopamine receptor availability in all regions. The striatal DAT availability was significantly increased in cocaine users. Methamphetamine users showed a significantly decreased dopamine receptor and transporter density in all regions. Significant results also indicate a lower transporter availability in all regions. Amphetamine users showed reduced DAT availability in the striatum, as well as in the sub regions.Conclusion: This meta-analysis provides evidence that there are ongoing changes in the dopaminergic system associated with the use of stimulants. Especially the results of cocaine, methamphetamine and amphetamine use mainly showed a downregulation. In addition, this meta-analysis is the first to include nicotine. This subset of studies showed evidence for a decreased receptor and DAT availability but no significant results were found in the metaanalyses.