Cortical thinning in amphetamine-type stimulant users

Accumulating evidence supports the hypothesis of ecstasy and amphetamine exhibiting neurotoxic properties in human recreational users. The extent and exact location of neuronal degeneration might also be associated with a specific profile of cognitive deterioration described in polydrug users. Voxel-based morphometry and cortical thickness analyses constantly gain attention for answering the question of associated neurological sequelae. We aimed to evaluate the integrity of cortical and subcortical structures in three groups that differ in the consumption of amphetamine-type stimulants. Cortical thickness, cortical grey matter volume and the shape of supposedly vulnerable subcortical structures were compared between 20 experienced users, 42 users with little exposure to these substances and 16 drug- naïve controls. Cortical thinning in experienced users compared to drug-naïve controls and low-exposure users was observed in medio-frontal regions. Effects of ecstasy and amphetamine on cortical volume were similar to those of cortical thickness, with volume reductions primarily in frontal, but also in occipital and parietal regions of low exposure and experienced users. These effects were differently lateralized for the different comparisons. The investigation of subcortical structures revealed non-significant bilateral shape differences in the hippocampi. Our data support the hypothesis that massive recreational amphetamine-type stimulant polydrug use is associated with a thinning of cortical grey matter. Disrupted neuronal integrity in frontal regions does fit well into models of addiction and the cognitive deterioration in amphetamine-type stimulant polydrug users. The exact neurotoxic mechanisms of polydrug ecstasy and amphetamine use, however, remain speculative.