This review provides a critical analysis of the central nervous system effects of acute and chronic methamphetamine (MA) use, which is linked to numerous adverse psychosocial, neuropsychiatric, and medical problems. A meta-analysis of the neuropsychological effects of MA abuse/dependence revealed broadly medium effect sizes, showing deficits in episodic memory, executive functions, information processing speed, motor skills, language, and visuoconstructional abilities. The neuropsychological deficits associated with MA abuse/dependence are interpreted with regard to their possible neural mechanisms, most notably MA-associated frontostriatal neurotoxicity. In addition, potential explanatory factors are considered, including demographics (e.g., gender), MA use characteristics (e.g., duration of abstinence), and the influence of common psychiatric (e.g., other substance-related disorders) and neuromedical (e.g., HIV infection) comorbidities. Finally, these findings are discussed with respect to their potential contribution to the clinical management of persons with MA abuse/dependence.

Neurocognitive Effects of Methamphetamine: A Critical Review and Meta-analysis

Deficits in response inhibition associated with chronic methamphetamine abuse

Cognitive deficits predict low treatment retention in cocaine dependent patients

Chronic methamphetamine (MA) abuse is associated with cerebral deficits, involving frontal/basal-ganglia regions that are important for inhibitory control. We used the Stop-Signal Task to measure response inhibition in 11 MA abusers (5–7 days abstinent) and two groups of control subjects who did not use MA (14 tobacco smokers and 29 non-smokers). Stop-signal reaction time (SSRT), which indicates the latency to inhibit an initiated motor response, was significantly longer for MA abusers than for either control group ( p’s < .01). In contrast, the MA abusers did not differ from either group on Go trial reaction time (RT) or number of discrimination errors, which reflect motor speed and decision-processes, respectively. MA abuse in this study was therefore associated with a specific deficit in inhibiting a pre-potent response. Future research could examine whether SSRT is different for MA abusers who respond to treatment compared to those who do not. If such differences are established then response inhibition may serve as a marker for investigating MA abuse in basic science and clinical trials. © 2005 Elsevier Ireland Ltd. All rights reserved.

Short communication Deficits in response inhibition associated with chronic methamphetamine abuse

Chronic consumption of several drugs of abuse (cannabis, stimulants, opioids) has been associated with the presence of neuropsychological impairments in a broad range of functions. Nevertheless, in recent years neuropsychological research on substance abuse has focused on the study of impairments in the executive functions linked to the prefrontal cortex and their influence on the personality, cognitions, and behaviors of the substance abusers. The aim of our review is, first, to summarize the main neuropsychological impairments shown by classic studies, as well as these new discoveries in executive functioning; second, to consider the mediating role of neuropsychological status on treatment outcomes and analyze the impact of these impairments in clinical practice with drug addicts; and third, to review the principal methodological challenges associated with research in the field of the neuropsychology of substance abuse. We also highlight the convenience of intervening in those functions most relevant to the abusers' persistence in consumption and risk of relapse.

William Fals-Stewart

Papers

Neurocognitive Defects and Their Impact on Substance Abuse Treatment