Freebase cocaine and memory

Neurocognitive Performance in Alcoholics: Is Polysubstance Abuse Important?

The neurocognitive effects of alcohol have been frequently examined. Studies reveal a wide array of cognitive deficits. Attempts to develop a parsimonious model for these effects have been difficult because of the intra- and intersubject variability. Complicating the development of a model of cognitive deficits in substance abusers is the common practice of polysubstance abuse. The use of theoretical models that focus on the underlying cognitive processes offers flexibility while maintaining sufficient theoretical precision. This article briefly reviews the literature on neurocognitive changes associated with substance abuse as well as the various theoretical models that have been studied. It also provides an overview of recovery of function. Its primary objective is to evaluate cognitive function among alcoholic subtypes, defined by patterns of other drug use. This analysis suggests there are significant differences in neurocognitive function among these subtypes.

Chronic and recreational use of cocaine is associated with a vulnerability to semantic interference

RATIONALE

Language production requires that speakers effectively recruit inhibitory control to successfully produce speech. The use of cocaine is associated with impairments in cognitive control processes in the non-verbal domain, but the impact of chronic and recreational use of cocaine on these processes during language production remains undetermined.

OBJECTIVES

This study aims to observe the possible impairment of inhibitory control in language production among chronic and recreational cocaine polydrug users.

METHOD

Two experiments were carried out on chronic (experiment 1) and recreational (experiment 2) cocaine polydrug users performing a blocked-cycled naming task, yielding an index of semantic interference. Participants were matched for sex, age, and intelligence (Raven's Standard Progressive Matrices) with cocaine-free controls, and their performance was compared on the blocked-cycled naming task.

RESULTS

Chronic and recreational users showed significantly larger semantic interference effects than cocaine-free controls, thereby indicating a deficit in the ability to inhibit interfering information.

CONCLUSION

Evidence indicates a relationship between the consumption of cocaine, even at recreational levels, and the inhibitory processes that suppress the overactive lexical representations in the semantic context. This deficit may be critical in adapting and responding to many real-life situations where an efficient self-monitoring system is necessary for the prevention of errors.

Crack cocaine use impairs anterior cingulate and prefrontal cortex function in women with HIV infection

Crack cocaine use is associated with impaired verbal memory in HIV-infected women more than uninfected women. To understand the neural basis for this impairment, this study examined the effects of crack cocaine use on activation of the prefrontal cortex (PFC) and strategic encoding during a verbal memory task in HIV-infected women. Three groups of HIV-infected women from the Chicago Consortium of the Women's Interagency HIV Study were compared: current users of crack cocaine (n = 10), former users of cocaine (n = 11), and women who had never used cocaine (n = 9). Participants underwent functional magnetic resonance imaging during a verbal memory task and completed a neuropsychological test of verbal memory. On the neuropsychological test, current crack users performed significantly worse than other groups on semantic clustering, a measure of strategic encoding, p < 0.05. During encoding, activation in left anterior cingulate cortex (ACC) was lower in current and former cocaine users compared to never users. During recognition, activation in bilateral PFC, specifically left dorsal medial PFC and bilateral dorsolateral PFC, was lower in current and former users compared to women who had never used cocaine. Lower activation in left dorsolateral PFC was correlated with worse performance on the recognition task, p < 0.05. The verbal learning and memory deficits associated with cocaine use in women with HIV may be partially accounted for by alterations in ACC and PFC function.

Elevated gray and white matter densities in cocaine abstainers compared to current users

RATIONALE

Numerous neuroimaging studies have demonstrated lower neural tissue density in chronic cocaine users, which may be linked to cognitive dysfunction.

OBJECTIVES

The goal of this study was to determine whether neural tissue density was also impaired in individuals abstinent from cocaine and whether any observed changes were associated with cognitive performance.

METHODS

A total of 73 participants were included: 24 active cocaine users, 24 abstainers (abstinent for at least 1 month), and 25 nondrug-abusing controls rigorously matched for age, gender, and IQ. All participants performed a cognitive assessment battery and received an MRI which was analyzed using voxel-based morphometry.

RESULTS

The abstainers had significantly higher gray matter density than the current cocaine users in neocortical areas including the frontal and temporal cortex. In contrast to the users, there was no difference in white matter density in the abstainers relative to the controls. The abstainers performed better than current users on several behavioral tasks. Within users and abstainers, cortical density was correlated with performance on memory and reaction time tasks. Subcortical gray matter density was lower in both the users and abstainers relative to the controls. Within abstainers, subcortical tissue density was correlated with the ability to set-shift.

CONCLUSIONS

These data suggest that individuals able to remain abstinent from cocaine for at least 1 month have elevated neocortical tissue density and perform better on multiple cognitive tests, relative to current cocaine users. Larger, longitudinal studies are needed to address this interaction between abstinence, cognition, and cortical tissue density directly.

Nondependent stimulant users of cocaine and prescription amphetamines show verbal learning and memory deficits

BACKGROUND

Stimulants are used increasingly to enhance social (cocaine) or cognitive performance (stimulants normally prescribed, prescription stimulants [e.g., methylphenidate, amphetamines]). Chronic use, by contrast, has been associated with significant verbal memory and learning deficits. This study sought to determine whether subtle learning and memory problems characterize individuals who exhibit occasional but not chronic use of stimulants.

METHODS

One hundred fifty-four young (age 18-25), occasional, nondependent stimulant users and 48 stimulant-naive comparison subjects performed the California Verbal Learning Test II. Lifetime uses of stimulants and co-use of marijuana were considered in correlation and median split analyses.

RESULTS

Compared with stimulant-naive subjects, occasional stimulant users showed significant performance deficits, most pronounced in the verbal recall and recognition domains. Lifetime uses of stimulants and marijuana did not affect California Verbal Learning Test II performance. The type of stimulant used, however, was of major relevance: users of cocaine only were less impaired, whereas cumulative use of prescription stimulants was associated with impaired verbal learning and memory capacities.

CONCLUSIONS

These results support the hypothesis of subtle and possibly pre-existing neurocognitive deficiencies in occasional users of stimulants, which might be related to the motivation for using these drugs. More importantly, despite beneficial short-term effects, cumulative use, particularly of prescription amphetamines and methylphenidate, intensifies these deficits.

Amnestic effect of cocaine after the termination of its stimulant action

The effects of cocaine on memory are controversial. Furthermore, the psychostimulant action of cocaine can be a critical issue in the interpretation of its effects on learning/memory models. The effects of a single administration of cocaine on memory were investigated during the presence of its motor stimulating effect or just after its termination. The plus-maze discriminative avoidance task (PM-DAT) was used because it provides simultaneous information about memory, anxiety and motor activity. In Experiment I, mice received saline, 7.5, 10, 15 or 30 mg/kg cocaine 5 min before the training session. In Experiment II, mice were trained 30 min after the injection of saline, 7.5, 10, 15 or 30 mg/kg cocaine. In Experiment III, mice received 30 mg/kg cocaine 30 min pre-training and pre-test. In Experiment IV, mice received 30 mg/kg cocaine immediately post-training. Tests were always conducted 24 h following the training session. Given 5 min before training, cocaine promoted a motor stimulant effect at the highest dose during the training session but did not impair memory. When cocaine was injected 30 min pre-training, the drug did not modify motor activity, but produced marked amnestic effects at all doses tested. This amnesia induced by cocaine given 30 min pre-training was not related to a state-dependent learning because it was not abolished by pre-test administration of the drug. Post-training cocaine administration did not induce memory deficits either. Our results suggest that the post-stimulant phase is the critical moment for cocaine-induced memory deficit in a discriminative task in mice.

Impaired object recognition following prolonged withdrawal from extended-access cocaine self-administration

Cocaine addicts have a number of cognitive deficits that persist following prolonged abstinence. These include impairments in executive functions dependent on the prefrontal cortex, as well as deficits on learning and memory tasks sensitive to hippocampal function. Recent preclinical studies using non-human animals have demonstrated that cocaine treatment can produce persistent deficits in executive functions, but there is relatively little evidence that treatment with cocaine produces persistent deficits in performance on hippocampal-dependent tasks. We recently demonstrated that extended (but not limited) access to self-administered cocaine is especially effective in producing persistent deficits on a test of cognitive vigilance, and therefore, we used this procedure to examine the effects of limited or extended access to cocaine self-administration on recognition memory performance, which is sensitive to hippocampal function. We found that extended access to cocaine produced deficits in recognition memory in rats that persisted for at least 2 weeks after the cessation of drug use. We conclude that the deficits in learning and memory observed in cocaine addicts may be at least in part due to repeated drug use, rather than just due to a pre-existing condition, and that in studying the neural basis of such deficits procedures involving extended access to self-administered cocaine may be especially useful.

Performance on the Stroop predicts treatment compliance in cocaine-dependent individuals

Treatment dropout is a problem of great prevalence and stands as an obstacle to recovery in cocaine-dependent (CD) individuals. Treatment attrition in CD individuals may result from impairments in cognitive control, which can be reliably measured by the Stroop color-word interference task. The present analyses contrasted baseline performance on the color-naming, word-reading, and interference subtests of the Stroop task in CD subjects who completed a cocaine treatment trial (completers: N=50) and those who dropped out of the trial before completion (non-completers: N=24). A logistic regression analysis was used to predict trial completion using three models with the following variables: the Stroop task subscale scores (Stroop model); the Hamilton depression rating scale (HDRS) scores (HDRS model); and both the Stroop task subscale scores and HDRS scores (Stroop and HDRS model). Each model was able to significantly predict group membership (completers vs non-completers) better than a model based on a simple constant (HDRS model p=0.02, Stroop model p=0.006, and Stroop and HDRS model p=0.003). Models using the Stroop preformed better than the HDRS model. These findings suggest that the Stroop task can be used to identify cocaine-dependent subjects at risk for treatment dropout. The Stroop task is a widely available, reliable, and valid instrument that can be easily employed to identify and tailor interventions of at risk individuals in the hope of improving treatment compliance.

The effects of cocaine: a shifting target over the course of addiction

Repeated exposure to psychostimulant drugs such as cocaine has been shown in numerous studies to produce significant neuroadaptations in both structure and function throughout the brain. Nonhuman primate models provide a way to systematically evaluate these adaptations engendered by cocaine self-administration and simulate the progressive nature of cocaine addiction in humans. Functional activity, measured using the 2-[14C]deoxyglucose method, was evaluated at selected critical time points over the course of chronic cocaine self-administration in rhesus monkeys. The effects of cocaine exposure in the initial stages of self-administration resulted in changes in functional activity in a highly restricted network of interconnected brain regions when compared to activity in food-reinforced controls. This pattern of changes was confined mainly to ventromedial prefrontal cortex and ventral striatum. Following chronic exposure to cocaine self-administration, however, the spatial extent and intensity of significant alterations in functional activity expanded considerably. The shift in topography of these changes was orderly, originating ventromedially in the prefrontal cortical-ventral striatal network and expanding dorsally to encompass the dorsal striatum. A strikingly similar progression occurred within the cortical areas that project to each of these striatal regions. Preliminary studies suggest that this pattern is maintained despite periods of abstinence from cocaine. The shifting patterns of cerebral metabolic function that accompany longer durations of cocaine self-administration may underlie many of the characteristics of chronic drug exposure, and may provide transitional mechanisms to more compulsive cocaine use.

Formulating policies on the non-medical use of cocaine

The formulation of policy on cocaine, as on any other social issue, involves explicit or implicit cost-benefit analyses with many factors. Cocaine use carries many medical, psychiatric and social risks, and its inherent pharmacological risk of dependence is greater than for other drugs. The reported frequency of these problems has increased exponentially over the past fifteen years. However, current levels of use are decreasing in the general population, though still increasing among certain subpopulations in which it is accompanied by violent crime. On the other hand, the attempt to control use mainly or exclusively by reducing the supply has been of low efficacy and extremely expensive, in both human and monetary terms, for the consuming countries and economically and politically devastating for the producing countries. Yet past experience with other drugs suggests that legalization of cocaine would increase its use substantially. Moreover, legalization runs counter to public sentiment, even in those countries where the law is applied leniently against users and small-scale traffickers. The most practical policy appears to be to maintain prohibition as a sign of social disapproval, but to rely much more heavily on non-coercive measures to reduce demand by strengthening public consensus against all drug use.

Assessment of cognitive functioning of methadone-maintenance patients: impact of adult ADHD and current cocaine dependence

The purpose of this study was to determine if methadone-maintained patients (MMP) with cocaine dependence (CD) and/or adult Attention Deficit Hyperactivity Disorder (ADHD) exhibited compounded cognitive dysfunction associated with their poly-substance use and/or co-morbid psychiatric diagnoses. The sample consisted of 79 MMP (59% male, 51% Caucasian), maintained on methadone doses ranging from 40-130 mg/day, who were placed into one of four diagnostic categories: (1) a control group (no ADHD, no CD) (n = 24), (2) CD alone (n = 18), (3)ADHDalone (n = 18), and (4)ADHD+ CD(n = 19). The California Computerized Assessment Package (CalCAP) was administered to assess cognitive functioning requiring focused and sustained attention in a standardized fashion. There were no group differences on Simple Reaction tasks. Compared to the control group, the ADHD+ CD group was slower and less accurate on 33% of the Choice Reaction (CR) tasks. Specifically, individuals in the ADHD + CD group and the ADHD alone group performed significantly worse on tasks measuring attention and psychomotor responding. These tasks are associated with broader cognitive skills in working memory, language discrimination and flexibility of cognitive sets that may have implications for treatment outcome. Diagnostic services capable of identifying cognitive deficits among MMP with ADHD and/or CD are needed to maximize the likelihood of treatment success and to serve as an indicator for the efficacy of therapeutic approaches.

Chronic cocaine self-administration is associated with altered functional activity in the temporal lobes of non human primates

Previous studies utilizing a nonhuman primate model have shown that cocaine self-administration in its initial stages is accompanied by alterations in functional activity largely within the prefrontal cortex and ventral striatum. Continued cocaine exposure may considerably change this response. The purpose of the present investigation was to characterize the effects of reinforcing doses of cocaine on cerebral metabolism in a nonhuman primate model of cocaine self-administration, following an extended history of cocaine exposure, using the quantitative 2-[(14)C]deoxyglucose (2-DG) method. Rhesus monkeys were trained to self-administer 0.03 mg/kg/injection (n = 4) or 0.3 mg/kg/injection (n = 4) cocaine and compared to monkeys trained to respond under an identical schedule of food reinforcement (n = 6). Monkeys received 30 reinforcers per session for a total of 100 sessions. Metabolic mapping was conducted at the end of the final session. After this extended history, cocaine self-administration dose-dependently reduced glucose utilization throughout the striatum and prefrontal cortex similarly to the initial stages of self-administration. However, glucose utilization was also decreased in a dose-independent manner in large portions of the temporal lobe including the amygdala, hippocampus and surrounding neocortex. The recruitment of temporal structures indicates that the pattern of changes in functional activity has undergone significant expansion beyond limbic regions into association areas that mediate higher order cognitive and emotional processing. These data strongly contribute to converging evidence from human studies demonstrating structural and functional abnormalities in temporal and prefrontal areas of cocaine abusers, and suggest that substance abusers may undergo progressive cognitive decline with continued exposure to cocaine.

Neurocognitive deficits in cocaine users: a quantitative review of the evidence

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 < d < 1.10). Moderate to large effect sizes (d > 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.

Die neuropsychologischen Effekte von Kokain

Zusammenfassung: Kokainkonsumenten sind in der Regel entweder Gelegenheitskonsumenten mit geringem und relativ gut kontrollierbarem Kokainkonsum oder Kokainabhängige, die exzessiv große Mengen Kokain einnehmen (Binge-Taking). Neuropsychologische Untersuchungen bei Gelegenheitskonsumenten mit kleinen bis mittleren Kokaindosen, die geeignet sind, “Euphorie” und “Hochgefühle” auszulösen, ergaben bisher keine Hinweise auf neuropsychologische Funktionsbeeinträchtigungen in der akuten Phase. Vielmehr wurden in der akuten Kokainphase verbesserte Aufmerksamkeitsleistungen und schnellere Reaktionszeiten gemessen, die bis zum Beginn der postakuten Phase anhielten. Explizite Untersuchungen zur postakuten Phase oder Studien über die Effekte von Kokain in einem hohen Dosisbereich liegen derzeit nicht vor. Kokainabhängige weisen in einem Abstinenzzeitraum von bis zu mindestens 3 Monaten neuropsychologische, neurologische und unter Umständen auch psychiatrische Defizite auf. Deutliche Defizite abstinenter Kokainabhängiger wurden bei der Aufmerksamkeitsleistung, der Konzentration, der inhibitorischen Kontrolle und im Gedächtnis gefunden, wobei die verschiedenen Gedächtnistypen unterschiedlich betroffen sind. Kommt es bei Kokainabhängigen zu einer erneuten Kokaineinnahme, d.h. zu einer Binge-Phase, so ist unmittelbar danach in der so genannten Crash-Phase noch zusätzlich mit zum Teil schweren emotional-motivationalen Beeinträchtigungen zu rechnen.

Biological markers of cocaine addiction: implications for medications development

The search for effective medications for cocaine addiction has been elusive. The failure to find such medications so far could be due to poor understanding of the underlying biology both in the premorbid condition and following the disease state of chronic cocaine use. Population heterogeneity could be a major factor in response to medications. In an attempt to highlight the issue of biomarkers we reviewed physiological, neuroendocrine and neuroimaging studies to identify specific biological changes/markers that could be used to characterize subgroups among chronic cocaine users. Merging the biology within medications studies of cocaine abusers could prove useful for targeting specific pharmacological agents to subgroups of patients, prediction of response to medication and relapse to use.

A pilot trial of piracetam and ginkgo biloba for the treatment of cocaine dependence

BACKGROUND

Chronic cocaine use is associated with cognitive deficits that may reduce the effectiveness of psychosocial treatment and promote relapse in newly abstinent cocaine-dependent patients. Nootropic agents, such as piracetam and ginkgo biloba, may improve cognitive function and reduce the incidence of relapse in these patients.

METHODS

This was a 10-week, double-blind, placebo-controlled pilot trial involving 44 cocaine-dependent subjects. Subjects received either piracetam (4.8 g/day), ginkgo biloba (120 mg/day), or placebo. Subjects were required to attain abstinence from cocaine during a 2-week baseline phase demonstrated by providing at least one benzoylecgonine (BE)-negative urine toxicology screen. Outcome measures included treatment retention, urine toxicology screens, Clinical Global Impression (CGI) scores, and results from the Addiction Severity Index (ASI).

RESULTS

Ginkgo biloba was not superior to placebo in any outcome measure. Piracetam was associated with more cocaine use and lower CGI scores compared to placebo.

CONCLUSIONS

Neither piracetam nor ginkgo biloba appears to be a promising medication for the treatment of cocaine dependence.

Cognitive efficiency in stimulant abusers with and without alcohol dependence

BACKGROUND

Although previous studies have found stimulant (i.e., cocaine, methamphetamine) abusers and alcoholics to have neuropsychological deficits, research examining which cognitive abilities are most affected by concurrent exposure to these substances is lacking. To address this issue, detoxified men and women who met criteria for dependence of (a) alcohol only (ALC) (n = 15); (b) stimulants only (STIM) (n = 15); and (c) both alcohol and stimulants (A/STIM) (n = 15) were compared with age- and education-matched community controls (n = 15).

METHODS

Tasks that measured visual spatial skills, problem-solving and abstraction, short-term memory, cognitive flexibility, and gross motor speed were administered to participants. For each test, both speed and accuracy were assessed and an efficiency ratio (accuracy/time) was derived. Based on an average of these efficiency ratios, an overall performance index of cognitive efficiency was obtained.

RESULTS

Overall, controls performed more efficiently than all other groups. However, they were statistically significantly better only in relation to the A/STIM and STIM groups (p < 0.01). Individual comparisons revealed that the ALC group performed significantly better than the STIM group, although the ALC group did not differ from either the control or A/STIM groups (p </= 0.05). This pattern of results was relatively consistent across the individual subtests of problem-solving/abstraction, short-term memory, and cognitive flexibility.

CONCLUSIONS

As expected, substance abuse was associated with cognitive inefficiency. More importantly, these findings suggest that the cognitive effects of chronic stimulant abuse are not additive with those of alcohol abuse. That is, singly addicted stimulant abusers demonstrated similar or greater neurocognitive impairments than individuals who abuse alcohol and stimulants concurrently. The reason for this pattern is speculative but may be attributed to alcohol's opposing actions on cerebrovascular effects brought on by stimulant abuse.

Cognitive function in HIV-1-infected drug users

Loss of cognitive ability, the most common neuropsychological complication in HIV-1 disease, may influence compliance with treatment and has been associated with decreased functional capacity, as well as an increased risk of mortality. In HIV-1-infected drug users, cognitive impairment affecting attention, memory, planning of complex tasks, information processing, and motor processes, has been reported, similar to findings in predominantly HIV-1-infected nondrug-using cohorts. The issue of whether early signs of cognitive dysfunction can be identified in asymptomatic HIV-1-infected drug users remains controversial. Evaluation of potential confounding factors, such as drug abuse, age, education, nutritional status, which may influence cognitive function, is essential for determining the dominant cause of neuropsychological abnormalities. There is evidence for a time-limited, protective effect against the development of AIDS dementia with zidovudine therapy. The potential ability of other therapies (e.g., antioxidants, B-complex vitamins) to prevent neuronal damage and protect the brain remains to be determined.

Neurobiological adaptations to psychostimulants and opiates as a basis of treatment development

Abuse of illicit substances, in particular psychostimulants and opiates, is a worldwide public health issue. Chronic use of cocaine and amphetamine causes common neurobiological adaptations that may guide new treatment development. These include perturbations in dopamine and serotonin neurotransmission, leading to trials of antidepressants, and serotonin and dopamine augmentation strategies. The detection of cerebral perfusion abnormalities caused by psychostimulants has led to examination of antiplatelet and excitatory amino acid (EAA) antagonist therapies. Further, development of cocaine vaccines allows for testing of peripheral blockade approaches to cocaine addiction. New approaches to behavioral treatments for cocaine dependence are also reviewed. For opiate dependence, understanding of heroin's effects on mu and kappa opiate receptors has led to investigations of the partial mu agonist buprenorphine in opiate maintenance. Evidence for hyper-excitability of locus coeruleus (LC) noradrenergic neurons and EEA inputs to the LC guides trials of new alpha 2-adrenergic agonists and EEA antagonists to alleviate opiate withdrawal. Finally, clinical experience with withdrawal from methadone and LAAM has led to trials of antagonist-accelerated opiate withdrawal. Improved treatment of psychostimulant and opiate addiction is critically needed, and likely to have wide-reaching impact in health care and society.

Learning and memory impairment in cocaine-dependent and comorbid schizophrenic patients

Impairments in verbal learning and memory functioning have been found to be cardinal features among individuals with schizophrenia as well as among non-schizophrenic cocaine abusers. Cognitive deficits in these areas, moreover, have been associated with poor treatment response and short-term outcome. Little is known, however, about the acute effects of cocaine abuse on schizophrenic patients' learning and memory functioning. Consequently, a potentially reversible and treatable source of cognitive impairment has been virtually ignored. The present study examined the extent of verbal learning and memory impairment in a group of cocaine-dependent schizophrenic patients (n=42) and a group of non-schizophrenic cocaine-dependent patients (n=21) within 72 h of the last cocaine use using the California Verbal Learning Test (CVLT). Schizophrenic patients (n=34) without any substance-use disorders were also tested in an identical time frame and served as a comparison group. Results revealed that all groups demonstrated significant learning and memory impairment relative to CVLT published age and gender corrected norms. Both cocaine-dependent and non-substance abusing schizophrenic groups presented a very similar pattern of impaired learning and recall performance across all CVLT task domains. Comorbid patients, in contrast, presented with marked deficits in their ability to learn and recall verbal information relative to either schizophrenic or cocaine-only groups. Moreover, the cocaine-abusing schizophrenic patients showed significant forgetfulness of the information that they did acquire during delayed recall conditions. The performance deficits exhibited by cocaine-abusing schizophrenic patients differed not only in relative severity of impairment, but also qualitatively in their increased rates of forgetfulness of acquired information. These results are interpreted in terms of the neurobiological substrates of learning and memory and the neurobiological impact of cocaine on schizophrenic patients' cognition during the early phase of inpatient hospitalization. These results suggest that comorbid patients should be targeted for specialized remediation efforts at the beginning phases of inpatient treatment.

The effect of cocaine on traumatic brain injury outcome: a preliminary evaluation

The effect of acute cocaine use on the functional and neuropsychological outcome of persons with traumatic brain injury, (TBI) was examined by comparing persons with TBI who tested positive for cocaine at the time of admission with persons with negative drug and alcohol screens. Subjects were matched for age, admission GCS score, level of education, and aetiology of injury (closed vs penetrating head injury). Dependent measures were: the Disability Rating Scale, the Functional Independence Measure, and selected neuropsychological tests. No group differences were found in DRS, FIM, FIM subsets, or FIM change. However, the cocaine group scored significantly lower than the no-drug group on the Rey Auditory Verbal Learning Test, but did not differ on any of the other neuropsychological tests.

Amlodipine treatment of cocaine dependence

Preclinical studies indicate that dihydropyridine-type calcium channel antagonists modulate dopamine neurotransmitter function and can reduce cocaine-reinforced behaviors. Amlodipine, a long-acting dihydropyridine-type calcium channel antagonist related to isradipine and nifedipine, was administered in open label fashion for 12 weeks to 26 cocaine-dependent patients. In subjects expressing cocaine craving, craving significantly declined during the course of the 12 weeks. Five individuals reported flushing, headache, fatigue, nocturia, nausea, and lightheadedness. No conclusions regarding efficacy can be made due to the small number of subjects and the open-label design.

Neuropsychologic findings in cocaine-dependent outpatients

1. Nineteen recently abstinent cocaine-dependent males were compared to 16 control subjects on a battery of neuropsychological tests. 2. The performance of cocaine-dependent subjects was inferior to the control group on tasks assessing higher level verbal skills, and on a task requiring logical sequencing of complex visual stimuli. 3. Cocaine users also performed poorly on a delayed visual memory task and on a verbal generation task, but performed better than the control group on a task assessing simple visual-motor speed. 4. Possible reasons for these findings are discussed, as are the treatment implications of these findings.

Cognitive efficiency in alcoholics and polysubstance abusers

Previous studies have found alcoholics to be impaired on tests of cognitive efficiency. However, it is unclear to what extent individuals who abuse drugs in addition to alcohol exhibit similar deficits. To answer this question, 63 healthy control subjects were compared with 40 individuals who abused alcohol only, 24 individuals who abused alcohol and stimulants, 16 individuals who abused alcohol and marijuana, and 41 individuals who abused alcohol and depressants/narcotics, or alcohol and two or more other drugs. All subjects were administered tests of short-term memory, spatial orientation, visual-spatial perception, and problem-solving. Results from the study indicated that control subjects and individuals who abused both alcohol and marijuana performed significantly better than the other groups on most tests. These results were not attributable to differences on measures of affect or chronicity of alcohol consumption.

Abstinent chronic crack-cocaine and crackcocaine/alcohol abusers evidence normal hippocampal volumes on MRI despite persistent cognitive impairments

We measured hippocampal volumes and cognitive functioning in crack-cocaine and crack-cocaine/alcoholdependent subjects (abstinent approximately 10-12 weeks) compared to age-matched controls. Cognitive function was evaluated using the computerized MicroCog Assessment of Cognitive Functioning (which includes tests of explicit, declarative memory subserved by the hippocampus). The hippocampal volumes were quantified on T1-weighted MRIs and were expressed as a proportion of intracranial vault volume. Both subjects and controls showed the larger right versus left hippocampal volume expected in normal anatomy, but we found no differences in hippocampal volume between any of the groups. However, both abstinent cocaine-dependent subjects and abstinent cocaine/alcohol-dependent subjects showed persistent cognitive impairments, including deficits in explicit memory. Our results suggest that either: (1) the hippocampus is resistant to structural volume loss in young and middle-aged cocaine or cocaine/alcohol-dependent subjects, (2) the hippocampal volume loss suffered by young and middle-aged cocaine or cocaine/alcohol-dependent subjects resolves after approximately 3 months of abstinence, or (3) hippocampal atrophy is obscured by the process of gliosis. Further, the cognitive impairments persisting in these abstinent cocaine and cocaine/alcohol-dependent samples may (1) be unrelated to hippocampal function or (2) be associated with abnormal hippocampal function that is not reflected in MRI measures of overall hippocampal atrophy.

Cocaine abuse and HIV-1 infection: epidemiology and neuropathogenesis

The epidemiology of cocaine abuse and potential relationships of cocaine withdrawal to human immunodeficiency virus type 1 (HIV-1)-associated dementia (HAD) are discussed. Neuroendocrinological changes in HIV-1 infection of the central nervous system (CNS) are discussed with the relevant impact of cocaine abuse. HIV-1 load in the brain tissue of infected substance users is described along with possible associations with neuropathology and HAD. Finally, the molecular epidemiology and sequence heterogeneity of HIV-1 and their implications for neuropathogenesis are summarized. The complex context of addressing cocaine abuse in the setting of HIV-1 infection appears more tractable when decomposed into its components.

Neurobiology of cocaine-induced organic brain impairment: contributions from functional neuroimaging

The present review is directed at imparting the current knowledge regarding functional neuroimaging as a tool for enhancing the understanding of cerebrophysiologic and neurobehavioral consequences of stimulant abuse. Stimulants like cocaine are capable of inducing clinically significant neurocognitive impairment through direct action on the brain, and indirectly through other organs that influence cerebral physiology. Neurochemical dysregulation including profound effects on the serotonergic and dopaminergic systems have substantial physiological and neurobehavioral consequences. Brain hemorrhages, transient ischemic attacks, strokes,and seizures frequently follow cocaine use. The residual cerebropathologic consequences of cocaine are seen only in significant or pronounced brain events when structural neuroimaging techniques such as computed tomography (CT) and magnetic resonance imaging (MRI) are employed. However, recent research with newer functional neuroimaging techniques such as single photon emission, positron emission tomography, and quantitative electroencephalography have revealed high rates of significant alteration in brain function among cocaine users, with negative structural imaging studies. These findings are often associated with impairment on neuropsychological evaluation, also in the absence of positive findings on CT and MRI. Both cerebral metabolic and hypoperfusion anomalies are seen, especially in anterior and temporal brain regions. Observed changes can persist for months, and for some patients, may represent a permanent change in brain functioning.

Pharmacotherapy of cerebral ischemia in cocaine dependence

This paper will examine how cerebral perfusion deficits in cocaine abusers may be a target for pharmacotherapy. The review covers five areas: (1) cerebral ischemia and neuropsychological impairment in cocaine abusers, (2) neuroimaging evidence for cerebral perfusion defects in cocaine abusers, (3) mechanisms for cocaine induced cerebral thrombosis, (4) neurotoxicity from cerebral ischemia and excitatory amino acids, (5) glutamate antagonists as potential treatment agents for cocaine induced neurotoxicity. Several pharmacotherapies are suggested including antiplatelet agents and excitatory amino acid (EAA) antagonists such as lamotrigine. Clinical trials in cocaine abusers with cerebral perfusion defects are indicated and EAA antagonists hold promise as they are developed for stroke treatment.

Neurochemical alterations in asymptomatic abstinent cocaine users: a proton magnetic resonance spectroscopy study

Cocaine can cause a variety of neuropsychiatric and neurobehavioral complications; however, it is uncertain whether cocaine causes persistent cerebral structural and neurochemical abnormalities in asymptomatic users. We studied 52 African-American men (26 human immunodeficiency virus-negative asymptomatic heavy cocaine users and 26 normal subjects). Ventricle-to-brain ratio (VBR) and white matter lesions (WML) were quantified on magnetic resonance imaging. N-acetyl-containing compounds (NA), total creatine, choline-containing compounds, myo-inositol, and glutamate + glutamine were measured with in vivo proton magnetic resonance spectroscopy, VBR and WML were not significantly different in the cocaine users compared to the normal controls. Elevated creatine (+7%; p = .05) and myo-inositol (+18%; p = .01) in the white matter were associated with cocaine use. NA, primarily a measure of N-acetyl aspartate and neuronal content, was normal. Normal NA suggest no neuronal loss or damage in the brain regions examined in these cocaine users. Therefore, we conclude that neurochemical abnormalities observed might result from alterations in nonneuronal brain tissue.

Neuropsychological differences between alcohol-dependent and cocaine-dependent patients with or without problematic drinking

The present study evaluated differences among three groups of substance abusers, abstinent for 1-5 months. One group was composed of 17 alcohol-dependent patients. The other two groups were composed of cocaine-dependent patients who scored below (n = 29) or above (n = 18) the median Michigan Alcoholism Screening Test (MAST) score for the cocaine-dependent group in total. The Shipley Institute of Living Scale was administered to all subjects. An ANOVA, with age as a covariate, revealed that the cocaine-dependent group with lower MAST scores exhibited statistically significant impairments on the Shipley abstraction subtest and on total IQ relative to the two other groups. There were no group differences on the verbal subtest. The abstraction and IQ deficits in the lower MAST score cocaine-dependent group could not be explained by decreased verbal abilities, a greater duration or frequency of cocaine use, or by a higher prevalence of Antisocial Personality Disorder. However, a chi 2 analysis revealed that this group contained more individuals who used cocaine in its 'freebase' or smoked form. Since the two cocaine-dependent groups were comparable in demographic and psychological characteristics, but had different levels of cocaine exposure, the results suggest that the decrements in abstraction scores reflect a cocaine-related effect.

Acute changes in cranial blood flow after cocaine hydrochloride

Cerebral blood flow (CBF) was measured with the 133Xenon inhalation technique and forehead skin flow with laser Doppler, before and twice after 0.3 milligram/kilogram of cocaine hydrochloride and a placebo given intravenously to six cocaine abusers, during two visits, separated by a minimum of one week. After cocaine, subjects showed significant increases in intoxication and tension. Systolic blood pressure and pulse rate also increased significantly after the drug but not after the placebo. CBF, with and without correction for end-tidal CO2, showed increases in left and right hemisphere after cocaine. The CBF increase was maximal in frontal, central and parietal regions. CBF changes correlated only with changes in a rated level of intoxication. Forehead skin flow did not change after cocaine or placebo. In habitual cocaine abusers, 0.3 mg/kg of cocaine, given intravenously produced increased CBF and no changes in forehead skin flow.

Effects of crack cocaine on neurocognitive function

Because crack cocaine appears to have a preferential effect on the metabolic and electrophysiological activity of the frontal and temporal regions of the brain (Pascual-Leone et al., 1991a, 1991b; Volkow, 1992), we hypothesized that cognitive measures of those regions would be impaired in crack cocaine users relative to measures in normal volunteers. We used logistic regression to determine the relationship of cocaine usage to neuropsychological test performance. We compared 38 patients with an average of 3.6 (SD = 2.5) years of crack cocaine use and 24.5 (SD = 28.1) days of abstinence to 54 normal volunteers on a battery of neuropsychological tests. Statistical adjustments were made for the effects of age, education, socioeconomic class, and level of depression. Our findings were mixed with regard to purported measures of executive/frontal functioning, with worse performance associated with cocaine usage on the Booklet Categories Test, but better performance associated on others (number of categories on the Wisconsin Card Sorting Test, Controlled Oral Word Association). Cocaine usage was associated with impairment on measures of spatial, but not verbal memory, confrontation naming, and Trail-making Test, Part B, a measure of perceptual-motor speed and cognitive flexibility. In summary, it appears that continuous crack cocaine use produces a dissociative pattern in neuropsychological test performance with improvement on some measures, but deterioration on others. The permanence of these effects remains to be determined with longitudinal studies.

Chronic cocaine use as a neuropsychiatric syndrome: a model for debate

In humans, chronic cocaine abuse is associated with changes in the central nervous system (CNS). Neuropathological changes include cerebrovascular events, EEG abnormalities, vasculitis, seizures, and decrements in neurobehavioral performance. The acute administration of cocaine is associated with acute psychotic episodes and paranoid states while withdrawal from the drug is often associated with depressed mood. The mechanistic basis of these behavioral states is not known. Given the structural and functional changes associated with cocaine use, we propose that the chronic heavy use of cocaine may result in a neuropsychiatric syndrome which might be associated with neuropsychological changes that are not obvious during routine clinical evaluation of drug-using individuals. This disconnection syndrome, because of its sublety, might have deleterious effects on both acute and long-term therapeutic interventions with these subjects. An approach which deals with cocaine abuse as a neuropsychiatric disorder might be more beneficial to the long-term goal of treating these patients. This approach entails a neurobehavioral evaluation which will be comprised of a thorough neurological and psychiatric examination, neuropsychological testing, and imaging studies. The results of this evaluation would provide a more rational basis for cognitive and/or pharmacological therapies.

Predicting premorbid functioning in crack-cocaine abusers

The Wide Range Achievement Test (Revised) (WRAT-R) reading test, demographic variables and drug use severity were used to develop prediction equations to estimate premorbid ability in 92 cocaine abusers. WRAT-R reading was correlated significantly with full scale, verbal and performance IQ. Stepwise regression indicated that only WRAT-R reading score and age accounted for 23% of the variance in Full Scale IQ (FSIQ) and 28% in Verbal IQ (VIQ). Abstinence and severity of use variables did not correlate with nor predict IQ. Actual and predicted IQ scores were correlated significantly and did not differ based on within group t-tests. Thus, these formulas accurately estimate premorbid functioning in cocaine-dependent research patients with FSIQs in the average to low average range, replicating the results in normal adults with average IQs.

Cocaine-induced cerebrovascular impairment: challenges to neuropsychological assessment

The patient who presents for evaluation and/or subsequent treatment of a neurological or psychiatric complaint accompanied by a positive history of substance abuse has generally received only modest attention in the clinical practice literature. Significantly more clinical attention has focused on the neurobehavioral sequelae of more pronounced brain insults, despite the rapid emergence of literature detailing psychopharmacologic-induced changes in brain-behavior functioning. This article describes recent clinical research findings related to the neuropsychology of cocaine use and associated issues of neurobiology and psychopharmacology. A description of strategies that have proven effective for assessing this population will be discussed. An emphasis on neurocognitive impairment that may precede as well as occur consequent to cocaine use are also examined. The literature reviewed here generally supports the conclusion that subgroups of cocaine abusing patients may demonstrate sustained brain perfusion anomalies and persistent neurocognitive deficits.

Neuropsychological deficits in abstinent cocaine abusers: preliminary findings after two weeks of abstinence

Sixteen subjects hospitalized for treatment of cocaine dependence were administered a battery of neuropsychological tests within 72 h of last cocaine use and again approximately 2 weeks later. Twenty-one non-cocaine using control subjects, matched for age, gender, ethnicity and education, also received neuropsychological testing. Abstinence from mood altering substances during the 2-week study period was verified for both groups on three occasions using quantitative urine analysis. The results suggest that recent cocaine use is associated with impairment in memory, visuospatial abilities, and concentration during the acute phase of withdrawal, independent of withdrawal-related depression. Furthermore, many of these deficits appear to persist at least 2 weeks beyond cessation of cocaine use.

The treatment of cocaine abuse

Cocaine abuse surged in the 1980s, forcing reevaluation of its previously benign image. Snorted, smoked, and injected, the drug is more widely abused than ever and, the consequences are devastating. Medical complications are frequent and range from mild (eg, cough, itching, headache) to life-threatening (eg. stroke, seizure, cardiovascular failure). Behavioral disturbances constitute the most dramatic and widespread effects of intoxication and withdrawal. Psychopathologic responses may include perceptual disturbances (eg. hallucinations) agitation, aggression, delirium, confusion, and profound delusional ideation. The goals of treatment are abstinence, rehabilitation, and relapse prevention. Hospital care may be necessary in certain circumstances. Regardless of where treatment takes place, a comprehensive program of supportive care, behavioral therapy, urine monitoring, and often psychopharmacologic intervention is required.

A gender comparison of health status among users of crack cocaine

This study examines a population of inner-city crack cocaine users in Miami, Florida. Many study participants were also injection drug users; others were the sexual partners of injection drug users. In general, the self-reported health status of the study population was good, but men perceived their health in a more positive light than did women. HIV-seronegative men were most likely to report excellent or good health, and seropositive women reported the greatest incidence of poor health, regardless of the amount of crack use. Serostatus was statistically significant for women but not for men. Pneumonia was reported more frequently by women, while hepatitis and tuberculosis were reported more frequently by men. There was a significant gender difference in reported endocarditis among light users of crack, with more women that men reporting a history of endocarditis. Among sexually transmitted diseases, men reported more gonorrhea and women reported more syphilis. These gender differences were statistically significant only for heavy users of crack. A gender difference was evident in the HIV seropositivity rates, with 25.7% of men and 32.2% of women testing positive for antibodies to HIV. While this difference held true when frequency of crack use was controlled, the difference was not statistically significant. Women were significantly more likely than men to trade sex for drugs and/or money. Women who were heavy crack users traded most often and would be expected to be at correspondingly increased risk for HIV infection or transmission.

Neurobiology of cocaine abuse

The recent escalation of cocaine abuse has increased awareness of the need to understand the behavioral effects of cocaine and the determinants of those effects. Cocaine alters both conditioned and unconditioned behavior, and has prominent reinforcing and subjective effects that are particularly relevant to its abuse. An increase in CNS dopamine neurotransmission, resulting from a competitive blockade of high-affinity dopamine uptake mediated by both D1 and D2 dopamine receptors, is a primary determinant of the behavioral effects of cocaine. Either tolerance or sensitization may develop with repeated administration of cocaine. Dependence also develops, although the behavioral changes associated with cocaine withdrawal are subtle. Although numerous CNS changes have been associated with repeated administration of cocaine, the neuropharmacological mechanisms that underlie the behavioral changes that occur with repeated administration remain to be firmly established. Bill Woolverton and Ken Johnson stress that continued collaboration between behavioral pharmacologists and neuroscientists is critical for a complete understanding of the effects of cocaine.