Drug-related decrease in neuropsychological functions of abstinent drug users.
This article reviews neuropsychological performance in frequent users of cocaine, (meth)amphetamines, ecstasy, opiates, alcohol, and cannabis. We searched the scientific literature published in the last five years, focusing on studies that required at least 2 weeks of abstinence from drug use, and included a control group. All substances of abuse, except cannabis, were associated with sustained deficits in executive functioning, especially inhibition. In addition, verbal memory decrements were consistently found in cocaine, (meth)amphetamines and ecstasy users, but not in heroin or cannabis users. More specific executive functioning deficits were reported depending on the substance of abuse. Cocaine was associated with diminished cognitive flexibility, whereas (meth)amphetamines were associated with worse cognitive planning functions compared to controls. Opiate studies showed lower scores on verbal fluency in opiate dependent subjects compared to controls. Working memory and visuospatial abilities were compromised in alcohol abusers. In ecstasy users, inconsistent findings have been reported across neuropsychological domains, with the exception of inhibition and verbal memory. There was little evidence for sustained cognitive impairments in adult abstinent cannabis users. Recognition of neuropsychological problems related to different substances can help to select subjects that will benefit most from treatment. Furthermore, a better understanding of the neuropsychological impairments in drug abusing individuals could help to explain the remitting course of substance abuse disorders and to improve psychological interventions.