A neuroanatomical approach to examining changes in cognition: the long-term effects of chronic cocaine use

Cognitive deficits exhibited by human cocaine users have been shown to predict outcome of therapeutic treatments, so understanding the structural basis of these deficits is clinically important. Longitudinal cognitive assessments were made, using touch-screen based tasks, in two groups of rhesus monkeys: a chronic cocaine self-administration group, and a control water self-administration group. Structural changes in regions of the prefrontal cortex over time were determined by measuring changes in the volumes of gray matter from magnetic resonance images taken pre- and post-treatment. Linear regressions were run to correlate changes in cognition with structural changes over time. A positive correlation was observed between changes in visual working memory performance and changes in structure in the dorsolateral prefrontal cortex, area 8, area 10, and area 12 in the cocaine group, but not in the control group. In human studies, it is impossible to know if structural changes are a direct result of cocaine use or result from differences prior to drug use or other factors. The structural differences identified in this study strongly support a link between cocaine use and cognitive deficits, and will guide post-mortem studies into possible neurobiological mechanisms underlying the observed anatomical changes