SAR-39684-the-neurocircuitry-of-illicit-psychostimulant-addiction--an-_020713.pdf

Neuropsychological effects chronic use of

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Neuropsychological effects Chronic use of psychostimulants results in widespread impairments of neuropsychological functioning, including measures of memory, executive function, and mental flexibility. The primary brain regions mediating these cognitive impairments are the same as those implicated in the neurocircuitry of addiction, namely the PFC, AMG, HPC, and CSTC loops. Chronic cocaine users demonstrated impaired executive functions, including measures of attention, working memory, set-shifting, mental flexibility, and response inhibition. 108 In one measure of PFC-mediated executive function, the Wisconsin Card Sorting Task, both METH-dependent subjects and chronic cocaine users demonstrated significant impairments (ie, increased perseverative responding). 109–111 In addition, cocaine-dependent subjects exhibit poor performance on a delayed-discounting and reversal-learning task. 112 In another study, chronic cocaine users, but not AMPH users, demonstrated increased perseverative responding in a probabilistic reversal-learning task. 113 METH-dependent subjects also exhibit impaired global neuropsychological function, specifically in the domains of executive function, learning, motor ability, and speed of information processing. 114 These impairments improved significantly following a period of abstinence. 114 The same study found no effects of chronic METH use on measures of memory, working memory, or verbal abilities. 114 However, other studies found that METH-dependent subjects exhibited impaired visual memory and executive control of verbal learning. 115,116 Differences between these studies on the effects of METH on verbal processes and memory may be in part due to differing histories of METH use in METH-dependent subjects across studies. 2,3 METH-dependent subjects were also impaired in measures of real-life skills, such as comprehension, finance, transportation, communication, and medication management. 109 In addition, METH abusers demonstrated impaired social cognition, as measured by facial emotion- recognition tasks, especially with respect to fear recognition. 111 Interestingly, impairments in executive function and social cognition have been found to be positively correlated. 4,111,117 In another study, METH-dependent subjects demonstrated slower reaction times and increased error and response-inhibition rates on a “go/no go” task. 118 These performance deficits were more severe in the presence of cue-elicited craving. 118 Neurological and psychiatric effects Psychosis is a common effect of chronic psychostimulant abuse. Psychotic symptoms include both hallucinations and delusions. Lifetime use of cocaine, but not AMPH, is associated with the experience of psychotic symptoms after adjusting for demographic covariates, comorbidity, and childhood adversity. 119 Severity of psychosis as a result of long-term psychostimulant abuse is increased in those that begin using at younger ages and use for longer periods of time.
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