Methamphetamine use is on the rise, with an imminent upsurge of abuse and dependence reported across the United States. Currently, preliminary evidence suggests that methamphetamine dependence may cause long-term neural damage in humans, with concomitant deleterious effects on cognitive processes such as memory and attention. This selective review provides an outline and synthesis of studies that assess the neurotoxic mechanisms of methamphetamine, as well as those that evaluate the cognitive sequelae of methamphetamine abuse.

https://neuro.psychiatryonline.org/doi/pdfplus/10.1176/jnp.15.3.317

Neuropsychological effects of chronic methamphetamine use on neurotransmitters and cognition: a review

Studies on the neurocognitive effects of cocaine abuse are equivocal with respect to the specific types of deficits observed, although the vast majority of studies indicate that at least some deficits in certain broad functions such as attention, learning and memory, executive functions, and response speed exist. All of these studies based their results on null hypothesis statistical significance testing (NHSST). It is argued that effect size analysis, which provides information about the magnitude of difference, offers a more valid index of cognitive impairments in a population when compared to NHSST. Accordingly, the objective of the current study was to conduct an effect size analysis (or a meta-analysis in cases where the same test measure was utilized in more than one study) to determine the type and the magnitude of the specific cognitive deficits found as a result of cocaine use. Effect sizes were calculated for each test variable across 15 empirical studies that met inclusion criteria. The results from 481 cocaine users and 586 healthy normal controls revealed that cocaine use had the largest effect on several measures of attention (0.40 0.50) were also obtained on tests of visual memory and working memory. Minimal effect sizes (d < 0.30) were obtained on tests of verbal fluency and other language functions and sensory-perceptual functions. Tests of executive functioning produced mixed findings and were interpreted in terms of degree rather than nature of impairment. The results are consistent with findings from neuroimaging and neurochemical studies that have found cocaine use to be associated with dysfunctions in the anterior cingulate gyrus and orbitofrontal cortex; these regions are highly implicated in the mediation of attentional and executive functions, respectively. Methodological limitations of the empirical studies included in the analysis are discussed.

Neurocognitive Deficits in Cocaine Users: A Quantitative Review of the Evidence

The Role of Acetylcholine in Cocaine Addiction

Cerebellar gray matter volume correlates with duration of cocaine use in cocaine-dependent subjects.

Background Cocaine use disorder is associated with cognitive deficits. However, the literature remains somewhat ambiguous with respect to which distinct cognitive functions are the most impaired in cocaine use disorder and to how duration of abstinence affects cognitive recovery. Here, we performed a meta-analysis to determine the cognitive domains impaired in cocaine abuse/dependence and the duration of abstinence necessary to achieve cognitive recovery. Methods A literature search yielded 46 studies that assessed cognitive dysfunction in subjects with cocaine abuse/dependence. Effect-size estimates were calculated using the Comprehensive Meta-Analysis V2, for the following 11 cognitive domains: attention, executive functions, impulsivity, speed of processing, verbal fluency/language, verbal learning and memory, visual learning and memory, visuospatial abilities, and working memory. Within these 11 domains, effect-size estimates were calculated on the basis of abstinence duration: short- (positive for drugs urine screening), intermediate- (≤12 weeks), and long-term (≥20 weeks) abstinence. Results Findings revealed moderate impairment across 8 cognitive domains during intermediate abstinence. The most impaired domains were attention, impulsivity, verbal learning/memory, and working memory. For some domains (attention, speed of processing, and verbal learning/memory), impairments were smaller during short-term abstinence than during intermediate abstinence. Finally, small effect-size estimates were found for long-term abstinence. Discussion These results suggest significant impairment across multiple cognitive domains in cocaine abusers, and that some of these deficits may be partially masked by the residual or acute withdrawal effects of cocaine. Cognitive dysfunctions remain stable during the first months of abstinence and may abate after 5 months of sobriety.

Cocaine and cognition: a systematic quantitative review.

Previous research suggests that cocaine abuse may result in neuropsychological deficits. To examine this further, we compared cocaine-withdrawn patients (N = 35) to normal controls (N = 17) on tasks of attention, concentration, perceptual-motor speed, and cognitive flexibility. The withdrawn cocaine patients performed significantly worse on Arithmetic, Grooved Peg Board Dominant and Non-Dominant, and Trails B tests. These findings suggest that withdrawn cocaine-dependent patients have more neuropsychological impairment than normal controls.

Neuropsychological deficits in withdrawn cocaine-dependent males.

BACKGROUND We have previously reported that people who are cocaine-dependent have reduced blue cone b-wave electroretinogram (ERG) responses. In this preliminary study, we examined the relationship between blue cone ERG amplitudes and craving response to cocaine cues.

METHOD A new series of 14 recently withdrawn subjects who were cocaine-dependent completed a cocaine craving questionnaire at baseline, and again following exposure to laboratory cues; an ERG was also performed.

RESULTS Cocaine-dependent subjects with a blunted ERG blue cone response (< 0.5 microV) showed significantly greater increases in craving following cue-exposure than subjects without the blunted ERG blue cone response.

CONCLUSIONS Subjects with a blunted ERG response may represent a subgroup more vulnerable to cocaine craving and relapse.

Sandra Santana

Papers

Neuropsychological deficits in withdrawn cocaine-dependent males.

Electroretinogram in withdrawn cocaine-dependent subjects. Relationship to cue-elicited craving.