Neuropsychological functioning in cocaine abusers with and without alcohol dependence

Plasma Concentrations of Neurofilament Light Chain Protein and Brain-Derived Neurotrophic Factor as Consistent Biomarkers of Cognitive Impairment in Alcohol Use Disorder

For a long time, Substance Use Disorders (SUDs) were not considered a component in the etiology of dementia. The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders introduced substance-induced neurocognitive disorders, incorporating this notion to clinical practice. However, detection and monitoring of neurodegenerative processes in SUD patients remain a major clinical challenge, especially when early diagnosis is required. In the present study, we aimed to investigate new potential biomarkers of neurodegeneration that could predict cognitive impairment in SUD patients: the circulating concentrations of Neurofilament Light chain protein (NfL) and Brain-Derived Neurotrophic Factor (BDNF). Sixty SUD patients were compared with twenty-seven dementia patients and forty healthy controls. SUD patients were recruited and assessed using the Psychiatric Research Interview for Substance and Mental (PRISM) and a battery of neuropsychological tests, including the Montreal Cognitive Assessment test for evaluation of cognitive impairment. When compared to healthy control subjects, SUD patients showed increases in plasma NfL concentrations and NfL/BDNF ratio, as well as reduced plasma BDNF levels. These changes were remarkable in SUD patients with moderate-severe cognitive impairment, being comparable to those observed in dementia patients. NfL concentrations correlated with executive function and memory cognition in SUD patients. The parameters "age", "NfL/BDNF ratio", "first time alcohol use", "age of onset of alcohol use disorder", and "length of alcohol use disorder diagnosis" were able to stratify our SUD sample into patients with cognitive impairment from those without cognitive dysfunction with great specificity and sensibility. In conclusion, we propose the combined use of NfL and BDNF (NfL/BDNF ratio) to monitor substance-induced neurocognitive disorder.

Driving under the influence of drugs: Correlation between blood psychoactive drug concentrations and cognitive impairment. A narrative review taking into account forensic issues

Driving under the influence of alcohol has been shown to increase the risk of involvement in road traffic collisions (RTCs) however, less is known about the effects of illicit drugs, and a clear correlation between drug concentrations and RTC risk is still debated. The goal of this narrative review is to assess the current literature regarding the most detected psychoactive drugs in RTC (ethanol, amphetamines, cannabis, opioids and cocaine), in relation to driving performance. Evidence on impaired driving due to psychoactive substances, forensic issues relating to the assessment of the impact of drugs, blood cut-off values proposed to date as well as scientific basis for proposed legislative limits are discussed. At present there is no unequivocal evidence demonstrating a clear dose/concentration dependent impairment in many substances. Per se and zero tolerance approaches seem to have negative effect on drugged driving fatalities. However, the weight of these approaches needs further investigation.

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Driving under the influence of psychotropic substances has become a widespread phenomenon.

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Only a few substances have been reported to have a clear dose/concentration dependent impairment.

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Statistically significant differences should not be considered as clinically significant per se

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There is wide variability in legislative cut-offs.

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Detection limits seems to be the most public safety-oriented legislative approach.

Multiple Substance Use Disorders and Self-Reported Cognitive Function in U.S. Adults: Associations and Sex-Differences in a Nationally Representative Sample

Polysubstance use is a growing public health concern that has been associated with poor clinical outcomes. Compared to single-drug users, this population suffers greater deficits in cognitive function, which hinder treatment success and recovery. Despite its high prevalence and poor prognosis, epidemiological research on polysubstance use and accompanying cognitive profile is lacking. We investigated associations between numbers of past-year co-occurring substance use disorders (SUDs) and self-reported cognitive function using data from the National Epidemiologic Survey for Alcohol and Related Conditions III (NESARC-III). Regression analyses revealed a significant negative association between cognitive scores and numbers of past-year SUDs, which was moderated by sex. After adjusting for confounding variables, greater numbers of SUDs were associated with declining self-reported cognitive function, and this relationship was stronger among females. Our findings expand on current literature on cognitive impairments among polysubstance users and provide a novel, nuanced description of this relationship among the general population. We highlight the need for targeted and individualized treatment approaches in order to improve outcomes in this population.

Adverse effect of catechol-O-methyltransferase (COMT) Val158Met met/met genotype in methamphetamine-related executive dysfunction

INTRODUCTION

The Val allele of the Val158Met single-nucleotide polymorphism of the catechol-o-methyltransferase gene (COMT) confers greater catabolism of dopamine (DA) in the prefrontal cortex (PFC) than the Met allele. Met/Met homozygotes typically outperform Val-carriers on tests of executive function (EF), perhaps resulting from increased DA bioavailability. Methamphetamine (METH) causes large releases of DA, which is associated with neurotoxicity and executive dysfunction in chronic METH users. We hypothesized that, contrary to its effect in non-METH-using populations, slower DA clearance conferred by Met/Met will relate to worse EF in METH users.

METHODS

149 non-Hispanic White men, stratified by METH dependence (METH+/-) and COMT (Val/Val, Val/Met, Met/Met), completed three tests of EF: Wisconsin Card Sorting Test (WCST), Stroop Color-Word Test (Stroop), and Trail Making Test Part B (Trails B). Demographically-adjusted test scores were averaged to create an EF composite T-score. We examined the interaction of METH and COMT on the EF composite and individual test T-scores, controlling for premorbid functioning and alcohol use.

RESULTS

METH group differences in EF were evident only among Met/Met carriers (beta = -9.36, p < .001) but not among Val carriers: Val/Met (beta = -1.38, p = .44) and Val/Val (beta = -4.34, p = .10). These effects were most salient on the WCST.

CONCLUSIONS

In the pre-frontal hyperdopaminergic state triggered by methamphetamine, greater DA inactivation conferred by the Val allele may protect against METH-related executive dysfunction, suggesting genetically-driven differences in vulnerability to METH.

Conditional Effects of Lifetime Alcohol Consumption on Methamphetamine-Associated Neurocognitive Performance

OBJECTIVES

Methamphetamine (MA) dependence contributes to neurotoxicity and neurocognitive deficits. Although combined alcohol and MA misuse is common, how alcohol consumption relates to neurocognitive performance among MA users remains unclear. We hypothesized that alcohol and MA use would synergistically diminish neurocognitive functioning, such that greater reported alcohol consumption would exert larger negative effects on neurocognition among MA-dependent individuals compared to MA-nonusing persons.

METHODS

Eighty-seven MA-dependent (MA+) and 114 MA-nonusing (MA-) adults underwent neuropsychological and substance use assessments. Linear and logistic regressions examined the interaction between MA status and lifetime average drinks per drinking day on demographically corrected global neurocognitive T scores and impairment rates, controlling for recent alcohol use, lifetime cannabis use, WRAT reading performance, and lifetime depression.

RESULTS

MA+ displayed moderately higher rates of impairment and lower T scores compared to MA-. Lifetime alcohol use significantly interacted with MA status to predict global impairment (ORR = 0.70, p = .003) such that greater lifetime alcohol use increased likelihood of impairment in MA-, but decreased likelihood of impairment in MA+. Greater lifetime alcohol use predicted poorer global T scores among MA- (b = -0.44, p = .030) but not MA+ (b = 0.08, p = .586).

CONCLUSIONS

Contrary to expectations, greater lifetime alcohol use related to reduced risk of neurocognitive impairment among MA users. Findings are supported by prior research identifying neurobiological mechanisms by which alcohol may attenuate stimulant-driven vasoconstriction and brain thermotoxicity. Replication and examination of neurophysiologic mechanisms underlying alcohol use in the context of MA dependence are warranted to elucidate whether alcohol confers a degree of neuroprotection.

Alcohol Interaction with Cocaine, Methamphetamine, Opioids, Nicotine, Cannabis, and γ-Hydroxybutyric Acid

Millions of people around the world drink alcoholic beverages to cope with the stress of modern lifestyle. Although moderate alcohol drinking may have some relaxing and euphoric effects, uncontrolled drinking exacerbates the problems associated with alcohol abuse that are exploding in quantity and intensity in the United States and around the world. Recently, mixing of alcohol with other drugs of abuse (such as opioids, cocaine, methamphetamine, nicotine, cannabis, and γ-hydroxybutyric acid) and medications has become an emerging trend, exacerbating the public health concerns. Mixing of alcohol with other drugs may additively or synergistically augment the seriousness of the adverse effects such as the withdrawal symptoms, cardiovascular disorders, liver damage, reproductive abnormalities, and behavioral abnormalities. Despite the seriousness of the situation, possible mechanisms underlying the interactions is not yet understood. This has been one of the key hindrances in developing effective treatments. Therefore, the aim of this article is to review the consequences of alcohol's interaction with other drugs and decipher the underlying mechanisms.

Putative mechanisms of cognitive decline with implications for clinical research and practice

Multiple intrinsic and extrinsic mechanisms contribute to vulnerability of cognitive decline and nurses play a significant role in assisting individuals and families to use strategies for healthy cognitive aging. The objective of this narrative review is to provide a synthesis of the intrinsic and extrinsic mechanisms of cognitive decline and conditions that are associated with cognitive decline. Well-established intrinsic mechanisms of cognitive decline include aging, apolipoprotein E (APOE) ε4 carrier status, SORL1 mutations, neuroinflammation, mitochondrial dysfunction, amyloid deposition, and demyelination. Extrinsic risk factors include obesity, diabetes, hypertension, elevated lipid panel, metabolic syndrome, depression, traumatic brain injury, substance use, heart failure, and stroke. The various definitions of cognitive decline as well as the intrinsic and extrinsic factors that impact cognition as humans age should be incorporated in future clinical research studies. Nurses may use this information to help patients make lifestyle choices regarding cognitive health.

Correlation between Blood and Oral Fluid Psychoactive Drug Concentrations and Cognitive Impairment in Driving under the Influence of Drugs

BACKGROUND

The effects of drugs on driving performance should be checked with drug concentration in the brain and at the same time with the evaluation of both the behavioural and neurophysiological effects. The best accessible indicator of this information is the concentration of the drug and/or metabolites in blood and, to a certain extent, oral fluid. We sought to review international studies on correlation between blood and oral fluid drug concentrations, neurological correlates and cognitive impairment in driving under the influence of drugs.

METHODS

Relevant scientific articles were identified from PubMed, Cochrane Central, Scopus, Web of Science, Science Direct, EMBASE up to April 2017.

RESULTS

Up to 2010, no epidemiological studies were available on this matter and International scientists suggested that even minimal amounts of parent drugs in blood and oral fluid could affect driving impairment. More recently, epidemiological data, systematic reviews and meta-analysis on drugged drivers allowed the suggestion of impairment concentration limits for the most common illicit drugs. These values were obtained comparing driving disability induced by psychotropic drugs with that of established blood alcohol limits. Differently from ethyl alcohol where both detection methods and concentration limits have been well established even with inhomogeneity of ranges within different countries, in case of drugs of abuse no official cut-offs have yet been established, nor any standardized analytical protocols.

CONCLUSION

Multiple aspects of driving performance can be differently affected by illicit drugs, and even if for few of them some dose/concentration dependent impairment has been reported, a wider knowledge on concentration/impairment relationship is still missing.

Neuropsychological comparisons of cocaine versus methamphetamine users: A research synthesis and meta-analysis

BACKGROUND

Previous meta-analytical research examining cocaine and methamphetamine separately suggests potentially different neuropsychological profiles associated with each drug. In addition, neuroimaging studies point to distinct structural changes that might underlie differences in neuropsychological functioning.

OBJECTIVES

This meta-analysis compared the effect sizes identified in cocaine versus methamphetamine studies across 15 neuropsychological domains.

METHOD

Investigators searched and coded the literature examining the neuropsychological deficits associated with a history of either cocaine or methamphetamine use. A total of 54 cocaine and 41 methamphetamine studies were selected, yielding sample sizes of 1,718 and 1,297, respectively. Moderator analyses were conducted to compare the two drugs across each cognitive domain.

RESULTS

Data revealed significant differences between the two drugs. Specifically, studies of cocaine showed significantly larger effect-size estimates (i.e., poorer performance) in verbal working memory when compared to methamphetamine. Further, when compared to cocaine, methamphetamine studies demonstrated significantly larger effect sizes in delayed contextual verbal memory and delayed visual memory.

CONCLUSION

Overall, cocaine and methamphetamine users share similar neuropsychological profiles. However, cocaine appears to be more associated with working memory impairments, which are typically frontally mediated, while methamphetamine appears to be more associated with memory impairments that are linked with temporal and parietal lobe dysfunction.

Alcohol Interactions with Psychostimulants: An Overview of Animal and Human Studies

Alcohol consumption with psychostimulants is very common among drug addicts. There is little known about the possible pharmacological interactions between alcohol and psychostimulants. Among most commonly co-abused psychostimulants with alcohol are methamphetamine, cocaine, 3,4-methylenedioxymethamphetaminen, and nicotine. Co-abuse of alcohol with psychostimulants can lead to several neurophysiological dysfunctions such as decrease in brain antioxidant enzymes, disruption of learning and memory processes, cerebral hypo-perfusion, neurotransmitters depletion as well as potentiation of drug seeking behaviour. Moreover, co-abuse of alcohol and psychostimulants can lead to increase in heart rate, blood pressure, myocardial oxygen consumption and cellular stress, and the risk of developing different types of cancer. Co-abuse of alcohol with psychostimulants during pregnancy can lead to fetal brain abnormalities. Further studies are needed to investigate the pharmacokinetics, pharmacodynamics, and neurochemical changes on co-abuse of alcohol and psychostimulants.

Neuropsychological Consequences of Chronic Drug Use: Relevance to Treatment Approaches

Heavy use of drugs impacts of the daily activities of individuals in these activities. Several groups of investigators have indeed documented changes in cognitive performance by individuals who have a long history of chronic drug use. In the case of marijuana, a wealth of information suggests that heavy long-term use of the drug may have neurobehavioral consequences in some individuals. In humans, heavy cocaine use is accompanied by neuropathological changes that might serve as substrates for cognitive dysfunctions. Similarly, methamphetamine users suffer from cognitive abnormalities that may be consequent to alterations in structures and functions. Here, we detail the evidence for these neuropsychological consequences. The review suggests that improving the care of our patients will necessarily depend on the better characterization of drug-induced cognitive phenotypes because they might inform the development of better pharmacological and behavioral interventions, with the goal of improving cognitive functions in these subsets of drug users.

Effects of acute and chronic cocaine administration on titrating-delay matching-to-sample performance

The effects of cocaine were examined under a titrating-delay matching-to-sample procedure. In this procedure, the delay between sample stimulus offset and comparison stimuli onset adjusts as a function of the subject's performance. Specifically, matches increase the delay and mismatches decrease the delay. Titrated delay values served as the primary dependent measure. After establishing stable performance in pigeons, several behaviorally-effective doses of cocaine were administered acutely. Dose-related within-session decreases in titrated delay values were observed. Following acute determinations, the dose of cocaine that produced the most rapid decline without eliminating performance was administered prior to each daily session. Chronic administration resulted in performance trending toward control levels. A redetermination of the dose-response function following chronic exposure revealed reduced potency (i.e., tolerance) under cocaine on titrated delay matching-to-sample performance. Supplemental analyses suggest that cocaine may serve as a disruptor of the stimulus conditions in which the performance was established.

Neuropsychological consequences of alcohol and drug abuse on different components of executive functions

Several studies have shown alterations in different components of executive functioning in users of different drugs, including cannabis, cocaine and heroin. However, it is difficult to establish a specific association between the use of each of these drugs and executive alterations, since most drug abusers are polysubstance abusers, and alcohol is a ubiquitous confounding factor. Moreover, in order to study the association between consumption of different drugs and executive functioning, the patterns of quantity and duration of drugs used must be considered, given the association between these parameters and the executive functioning alteration degree. Based on the multicomponent approach to executive functions, the aims of the present study were: (i) to analyse the differential contribution of alcohol versus cocaine, heroin and cannabis use on executive functions performance; and (ii) to analyse the contribution made by the severity of the different drugs used (quantity and duration patterns) on these functions in a sample of polysubstance abusers that requested treatment for cannabis-, cocaine- or heroin-related problems. We administered measures of fluency, working memory, analogical reasoning, interference, cognitive flexibility, decision-making and self-regulation to two groups: 60 substance-dependent individuals (SDIs) and 30 healthy control individuals (HCIs). SDIs had significantly poorer performance than HCIs across all of the executive domains assessed. Results from hierarchical regression models showed the existence of common correlates of the use of alcohol, cannabis and cocaine on verbal fluency and decision-making; common correlates of quantity of cannabis and cocaine use on verbal working memory and analogical reasoning; common correlates of duration of cocaine and heroin use on shifting; and specific effects of duration of cocaine use on inhibition measures. These findings indicate that alcohol abuse is negatively associated with fluency and decision-making deficits, whereas the different drugs motivating treatment have both generalized and specific deleterious effects on different executive components.

Cognitive enhancement as a pharmacotherapy target for stimulant addiction

BACKGROUND

No medications have been proven to be effective for cocaine and methamphetamine addiction. Attenuation of drug reward has been the main strategy for medications development, but this approach has not led to effective treatments. Thus, there is a need to identify novel treatment targets in addition to the brain reward system.

AIM

To propose a novel treatment strategy for stimulant addiction that will focus on medications enhancing cognitive function and attenuating drug reward.

METHODS

Pre-clinical and clinical literature on potential use of cognitive enhancers for stimulant addiction pharmacotherapy was reviewed.

RESULTS AND CONCLUSIONS

Cocaine and methamphetamine users show significant cognitive impairments, especially in attention, working memory and response inhibition functions. The cognitive impairments seem to be predictive of poor treatment retention and outcome. Medications targeting acetylcholine and norepinephrine are particularly well suited for enhancing cognitive function in stimulant users. Many cholinergic and noradrenergic medications are on the market and have a good safety profile and low abuse potential. These include galantamine, donepezil and rivastigmine (cholinesterase inhibitors), varenicline (partial nicotine agonist), guanfacine (alpha(2)-adrenergic agonist) and atomoxetine (norepinephrine transporter inhibitor). Future clinical studies designed optimally to measure cognitive function as well as drug use behavior would be needed to test the efficacy of these cognitive enhancers for stimulant addiction.

The impacts of substance abuse and dependence on neuropsychological functions in a sample of patients from Saudi Arabia

BACKGROUND

A lot of studies were directed to explore the relation between drug abuse and neuropsychological functions. Some studies reported that even after a long duration of disappearance of withdrawal or intoxication symptoms, many patients have obvious deterioration of cognitive functions. The aim of this study was to explore the relationship between the substance use disorders and the executive functions.

METHODS

Two groups were selected for this study. An experimental group consisted of 154 patients and further subdivided according to the substance used into three different subgroups: opioid, amphetamine and alcohol groups which included 49, 56 and 49 patients respectively. The control group was selected matching the experimental group in the demographic characteristics and included 100 healthy persons. Tools used were: Benton visual retention tests, color trail making test, Stroop colors-word test, symbol digit modalities test, the five dots cognitive flexibility test, and TAM verbal flexibility test. All the data were subjected to statistical analysis

RESULTS

The study showed that the group of drug-dependent subjects performed significantly worse than the comparison group on all measures Also, there were significant differences among the subgroups as the alcoholic group was much worse followed by the amphetamine then the opioids groups. Patients with longer duration of dependence and multiple hospital readmissions were much worse in comparison to patients with shorter duration of dependence and less readmission.

CONCLUSION

The study confirmed that the functions of specific brain regions underlying cognitive control are significantly impaired in patients of drug addiction. This impairment was significantly related to type of substance, duration of use and number of hospitalization and may contribute to most of behavioral disturbances found in addicts and need much attention during tailoring of treatment programs.

Cognitive Performance by Humans During a Smoked Cocaine Binge-Abstinence Cycle

Five cocaine-dependent individuals completed a 22-day inpatient study of sleep and cognition. Following 3 days of drug-free baseline, participants underwent 3 days of twice-daily smoked cocaine base self-administration (6 50-mg doses, 14 minutes apart), followed by 15 days of abstinence. Each morning and afternoon, the CDR repeatable, multiple-version, computerized cognitive battery (whose stability following practice has been documented) was administered. During abstinence, performance deteriorated on vigilance tasks (especially reaction time) as well as on immediate and delayed verbal recognition tasks but not on working memory tasks. Declines were most evident in the afternoon. Data suggest that abstinence can unmask cognitive deficits induced by chronic cocaine use and circadian factors may mediate their severity.

Relation between cognitive testing performance and pattern of substance use in males at treatment entry

This study examined the frequency and pattern of cognitive impairment in individuals entering substance use disorder treatment and additionally examined the relation between pattern of cognitive impairment and type of substance(s) used: alcohol (n = 116), cocaine (n = 49), alcohol/cocaine (n = 76), and alcohol/multiple substance (n = 54). The Cognistat, a screening measure of cognitive functioning, and the Addiction Severity Index were given to male veterans at the time of entering 3- to 4-week residential/day drug treatment. The most prominent areas of impairment were memory (37% of the total sample) and similarities or abstract concept formation (21% of the total sample). Moderate or greater severity of impairment was noted on at least one Cognistat scale in 35% of the participants. Results indicated no significant differences in the patterns of cognitive domain impairment between groups based on type(s) of substances used at the time of entering treatment. Multiple substance use was significantly related to greater levels of psychiatric problems as identified by the Alcohol Severity Index. Given the rate of impairment in memory and verbal abstract reasoning noted, it is suggested that cognitive screening be a standard consideration in residential substance use disorder treatment to assist in treatment selection and delivery that is optimized to provide maximal benefit to patients.

ADH4 gene variation is associated with alcohol dependence and drug dependence in European Americans: results from HWD tests and case-control association studies

The alcohol dehydrogenase (ADH) family constitutes one of the key sets of enzymes responsible for the oxidation of alcohol. The ADH4 gene, an important member of this family, is a functional and positional candidate for alcohol dependence. The present study aimed to investigate the relationship between ADH4 gene variation and alcohol dependence and drug dependence in European-Americans (EAs) and African-Americans (AAs). Seven single nucleotide polymorphisms (SNPs) spanning the ADH4 gene were genotyped in 365 healthy controls (317 EAs and 48 AAs) and 561 subjects (400 EAs and 161 AAs) affected with alcohol dependence and/or drug dependence (436 with alcohol dependence; 356 with drug dependence). Hardy-Weinberg equilibrium (HWE) for the genotype frequency distributions of these markers was tested in all phenotype groups to evaluate association between ADH4 gene variation and phenotypes and to fine-map the disease risk locus. The allele, genotype, and haplotype frequency distributions of these markers were compared between cases and controls to confirm the associations. The genotype frequency distributions of ADH4 markers were in HWE in EA controls, but were in Hardy-Weinberg disequilibrium (HWD) (ie, deviation from HWE) in EA cases. Among all markers, SNP2 (rs1042363) at exon 9 or SNP6 (rs1800759) at the promoter showed the greatest degree of HWD, among patients with either alcohol dependence or drug dependence. Significant differences between EA cases and controls were seen for genotype (10(-6)<global p<0.044), but not any allele or haplotype, frequency distributions for all seven ADH4 markers. These findings suggest that ADH4 genotypes predispose to alcohol dependence and drug dependence in a recessive manner, a predisposition that is population specific. SNP2 or SNP6 was the marker genetically closest to the functional risk loci for both alcohol dependence and drug dependence.

Cocaine and the heart

Cocaine is the second commonest illicit drug used and the most frequent cause of drug related deaths. Its use is associated with both acute and chronic complications that may involve any system, the most common being the cardiovascular system. Cocaine misuse has a major effect in young adult drug users with resulting loss of productivity and undue morbidity with cocaine related cardiac and cerebrovascular effects. Many cocaine users have little or no idea of the risks associated with its use. Patients, health care professionals, and the public should be educated about the dangers and the considerable risks of cocaine use. This review concentrates on the cardiovascular effects of cocaine and their management.

Polydrug abusers display impaired discrimination-reversal learning in a model of behavioural control

Long-term cocaine and alcohol use is associated with neuropsychological impairments that implicate poor inhibitory mechanisms of behavioural control. This study tested acquisition and discrimination-reversal learning in a group of polydrug users (n 20) with a history of cocaine and heavy alcohol use and a group of age-matched controls (n 20). A cued go/nogo task measured subjects' ability to learn stimulus-response associations that involved the quick activation and sudden inhibition of responses. Compared with controls, drug users displayed similar acquisition, but impaired discrimination-reversal learning of both inhibitory and activational responses. The results suggest that some drug-related neuropsychological deficits might reflect specific impairments of the ability to inhibit interference from prior learning. The findings contribute to growing evidence that suggests cocaine and alcohol use could produce broad inhibitory impairments that increase the risk for learning deficits and poor impulse control.

The relation between ethnicity and cognistat performance in males seeking substance use disorder treatment

This study examined the relation between ethnicity and results obtained during standard administration of the Cognistat, a screening measure of cognitive functioning, in a sample of male veterans seeking substance use disorder treatment (n = 312). Results indicated that screening items for the Naming, Calculation, and Similarities subtests were missed significantly more frequently by African American compared to Caucasian veterans, although the frequency of identification as impaired on the full metric portion of this scales did not differ based on ethnicity. The mean scores on the metric items for these three scales were very similar between groups. Additionally, African American veterans diverted to the Constructional Ability metric items had significantly lower scores on items from that subtest. Logistic regression analyses of impairment identification on the various subtests indicated that ethnicity was a significant (p < .005) predictor beyond the covariates of age and years of education for the Calculation subtest, but only accounted for 4.8% of the variance. Based on the results of the current study, it is recommended that 1) the entire Cognistat be administered regardless of screening item performance to minimize the risk of potential ethnic or cultural based performance bias and 2) a prospective study of potential demographic bias based on comparing Cognistat screening results to a battery of specific neuropsychological assessments of the same constructs be performed to maximize the potential specificity and sensitivity of this assessment for all demographic groups.

Sex differences in neurocognitive functioning among abstinent recreational cocaine users

RATIONALE

There are clear sex differences in the onset and course of cocaine addiction, females being at greater risk. Neurocognitive impairments associated with cocaine use are also well documented. However, there are no studies of sex differences in neurocognitive performance among cocaine users.

OBJECTIVES

The present study was designed to examine, for the first time, putative sex-related variations in cognition among recreational cocaine users. It was predicted that female users would perform poorer compared with male users based on the worse effects of cocaine abuse in women.

METHODS

A neuropsychological battery was administered to abstinent (72 h) recreational cocaine users (20 males and 20 females) and non-drug-using controls (19 males and 20 females) including tests of attention, executive functioning, verbal fluency (letter and category), verbal memory and visuospatial perception.

RESULTS

Male users demonstrated poorer attention compared with male controls, and greater verbal recognition errors than male controls and female users. Female users did not differ significantly in any other cognitive domain compared with male users or female controls. These results remained after controlling for dose-dependent variables. General dose-dependent effects were found for attention, visuospatial perception and components of verbal memory.

CONCLUSIONS

Whilst these data partially support the notion of sex-related neurocognitive variation in short-term abstinence from recreational cocaine use, they do not suggest that sex is a major factor.

N400 as an index of semantic expectancies: differential effects of alcohol and cocaine dependence

BACKGROUND

Chronic substance abuse has been associated with decrements in the processing and expression of language. The present study utilized the N400 event-related electroencephalographic potential to index semantic processing in 133 adults with (n=49) or without (n=84) a history of alcohol and/or cocaine dependence. The contributions of age, gender, and comorbid marijuana and nicotine dependence, and antisocial symptomology to N400 decrements were either covaried or controlled.

METHODS

A continuous series of 300 stimuli was presented for 150 ms each (interstimulus interval=1475 ms) on a computer screen. The series was arranged such that a word (approximately 17% of stimuli) immediately preceded presentations of its antonym (primed condition; approximately 17% of stimuli), or a semantically unrelated word (unprimed condition; approximately 17% of stimuli). The remaining 50% of stimuli consisted of unpronounceable letter combinations (non-word condition). EEG responses to the antonyms, unrelated words, and letter jumbles were retained for analysis. Throughout the task, the subject pressed response keys to discriminate words from non-words.

RESULTS

Analyses revealed a detrimental effect of alcohol dependence on N400 amplitude and no significant main or interactive effects of cocaine dependence.

CONCLUSION

The present findings suggest that alcohol-dependent individuals may exhibit verbal processing decrements. These findings also challenge hypotheses suggesting that the combined use of cocaine and alcohol is more deleterious to brain function than alcohol use alone.

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.

Gene expression profiling in the brains of human cocaine abusers

Chronic cocaine abuse induces long-term neurochemical, structural and behavioural changes thought to result from altered gene expression within the nucleus accumbens and other brain regions playing a critical role in addiction. Recent methodological advances now allow the profiling of gene expression in human postmortem brain. In this article, we review studies in which we have used Affymetrix oligonucleotide microarrays to identify transcripts that are differentially expressed in the nucleus accumbens of cocaine abusers in comparison to well-matched control subjects. Of the approximately 39,000 gene transcripts interrogated, the expression of only a fraction of 1% is significantly modified in cocaine abusers. Found within this list are equivalent incidences of increased and decreased transcript abundance, including known gene transcripts clustered into several functional categories. A striking exception is a group of myelin-related genes, consisting of multiple transcripts representing myelin basic protein (MBP), proteolipid protein (PLP) and myelin-associated oligodendrocyte basic protein (MOBP), which as a group are substantially decreased in cocaine abusers compared to controls. These data, suggesting a possible dysregulation of myelin in cocaine abusers, are discussed in the context of myelin-related changes in other human brain disorders. Finally, the effects of cocaine abuse on the profile of gene expression in some other brain regions critical for addiction (the prefrontal cortex and ventral midbrain) are briefly reviewed.

The Effect of Alcohol on the Neuropsychological Functioning of Recently Abstinent Cocaine-dependent Subjects

Neuropsychological deficits in the areas of learning, memory, attention, and abstraction abilities have been associated with cocaine dependence, especially during the period of early abstinence. Although cocaine users tend to be multidrug users, few studies have focused on the combined effect of alcohol and cocaine on neuropsychological functioning. Consistent with prior research, results from the current study indicated that cocaine-dependent subjects showed a significantly greater degree of neuropsychological impairment as compared to controls. In addition, cocaine-dependent subjects with a history of alcohol disorder showed less memory impairment but similar impairments in attention and overall neuropsychological functioning as cocaine subjects with no such history. The vasodilatation produced by alcohol may attenuate some of the vasoconstriction and neurotoxic effects of cocaine, accounting for the fewer deficits in this group.

Severity of neuropsychological impairment in cocaine and alcohol addiction: association with metabolism in the prefrontal cortex

We used exploratory and confirmatory statistical approaches to study the severity of neuropsychological (NP) impairment in 42 crack/cocaine addicted subjects and in 112 comparison subjects (40 alcoholics and 72 controls). Twenty neuropsychological test indices most reliably defining predetermined cognitive domains were submitted to exploratory factor analysis. A four-dimensional model of neurocognitive function was derived: Verbal Knowledge, Visual Memory, Verbal Memory, and Attention/Executive functioning accounted for 63% of the variance. We then examined this model's association with resting glucose metabolism in the brain reward circuit measured with 2-deoxy-2[18F]fluoro-D-glucose positron emission tomography. Results revealed that (1) cocaine addicted individuals had a generalized mild level of neurocognitive impairment (<1 S.D. below control mean); and (2) controlling for age and education, relative metabolism in the dorsolateral prefrontal cortex significantly predicted the Visual Memory and Verbal Memory factors and relative metabolism in the anterior cingulate gyrus significantly predicted the Attention/Executive factor. Nevertheless, it remains to be determined whether metabolic changes in these regions are associated with addiction. Our results also suggest that compared to cocaine, alcohol has a more detrimental effect on Attention/Executive functioning, as assessed with traditional NP measures. We conclude that relative to other psychopathological disorders (such as schizophrenia), the severity of neuropsychological impairment in cocaine addiction is modest, albeit not indicative of the absence of neurocognitive dysfunction. The impact of such small differences in performance on quality of life, and possibly on craving and relapse, may be substantial. Tasks that simulate real-life decision-making or that target specific putative cognitive-behavioral or motivational-emotional mechanisms might offer greater sensitivity in characterizing the changes that accompany addiction to drugs. Obtaining valid estimates of alcohol use in cocaine addicted subjects is essential in characterizing neurocognitive functioning in individuals addicted to drugs.

Gene expression profile of the nucleus accumbens of human cocaine abusers: evidence for dysregulation of myelin

Chronic cocaine abuse induces long-term neural adaptations as a consequence of alterations in gene expression. This study was undertaken to identify those transcripts differentially regulated in the nucleus accumbens of human cocaine abusers. Affymetrix microarrays were used to measure transcript abundance in 10 cocaine abusers and 10 control subjects matched for age, race, sex, and brain pH. As expected, gene expression of cocaine- and amphetamine-regulated transcript (CART) was increased in the nucleus accumbens of cocaine abusers. The most robust and consistent finding, however, was a decrease in the expression of a number of myelin-related genes, including myelin basic protein (MBP), proteolipid protein (PLP), and myelin-associated oligodendrocyte basic protein (MOBP). The differential expression seen by microarray for CART as well as MBP, MOBP, and PLP was verified by RT-PCR. In addition, immunohistochemical experiments revealed a decrease in the number of MBP-immunoreactive oligodendrocytes present in the nucleus accumbens and surrounding white matter of cocaine abusers. These findings suggest a dysregulation of myelin in human cocaine abusers.

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.

Effects of concurrent use of alcohol and cocaine

The combination of alcohol and cocaine is popular among drug users, perhaps because of more intense feelings of 'high' beyond that perceived with either drug alone, less intense feelings of alcohol-induced inebriation and tempering of discomfort when coming down from a cocaine 'high'. A review is presented of the medical literature on psychological and somatic effects and consequences of combined use of alcohol and cocaine in man. The search was carried out with Medline, the Science Citation Index/Web of Science and Toxline. Exclusion and inclusion criteria for this search are identified. There is generally no evidence that the combination of the two drugs does more than enhance additively the already strong tendency of each drug to induce a variety of physical and psychological disorders. A few exceptions must be noted. Cocaine consistently antagonizes the learning deficits, psychomotor performance deficits and driving deficits induced by alcohol. The combination of alcohol and cocaine tends to have greater-than-additive effects on heart rate, concomitant with up to 30% increased blood cocaine levels. Both prospective and retrospective data further reveal that co-use leads to the formation of cocaethylene, which may potentiate the cardiotoxic effects of cocaine or alcohol alone. More importantly, retrospective data suggest that the combination can potentiate the tendency towards violent thoughts and threats, which may lead to an increase of violent behaviours.

Perfusion MRI and computerized cognitive test abnormalities in abstinent methamphetamine users

This study aims to determine possible persistent abnormalities in regional cerebral blood flow (relative rCBF) and cognitive function in abstinent methamphetamine (METH) users. Twenty METH-dependent subjects (abstinent for 8+/-2 months) and 20 age- and gender-matched controls were evaluated with perfusion magnetic resonance imaging (pMRI) and neuropsychological tests. METH users showed decreased relative rCBF bilaterally in putamen/insular cortices (right: -12%; left: -10%) and the right lateral parietal brain region (-11%), but increased relative rCBF bilaterally in the left temporoparietal white matter (+13%), the left occipital brain region: (+10%) and the right posterior parietal region (+24%). Interaction effects were observed between METH and gender in the right occipital cortex and a midline brain region; female METH users showed increased relative rCBF (+15% both regions) whereas the male METH users had decreased relative rCBF (-10% and -18%, respectively). METH users performed within normal ranges on standard neuropsychological tests; however, they were slower on several tasks on the California Computerized Assessment Package (CalCAP), especially tasks that required working memory. These findings suggest that METH abuse is associated with persistent physiologic changes in the brain, and these changes are accompanied by slower reaction times on computerized measures of cognitive function.

Neuropsychological performance of individuals dependent on crack-cocaine, or crack-cocaine and alcohol, at 6 weeks and 6 months of abstinence

BACKGROUND

Little data exist on the neuropsychological effects of crack-cocaine dependence or crack-cocaine and alcohol dependence. This study examined cognitive function in abstinent crack dependent and crack and alcohol dependent individuals at 6 weeks and 6 months abstinence.

METHODS

a comprehensive neuropsychological battery, including the MicroCog computerized assessment, was administered to 20 abstinent crack dependent subjects, 37 abstinent crack and alcohol dependent subjects, and 29 normal controls. Depression was examined as a covariate, and the association between substance use variables and neuropsychological performance was examined.

RESULTS

the two substance dependent groups had similar neuropsychological profiles at 6 weeks abstinent, with both groups exhibiting significant cognitive impairment in a wide range of functions compared to controls. The substance dependent groups were still impaired significantly at 6 months of abstinence. Only mild effects of depression on neuropsychological performance were observed.

CONCLUSIONS

crack dependence and crack and alcohol dependence may lead to severe and persistent neuropsychological deficits over a wide range of domains. The strongest predictor of brain damage associated with substance dependence in this sample was dose (particularly quantity and duration of peak dose).

Investigating the neurocognitive deficits associated with chronic drug misuse

Cognitive deficits associated with the chronic abuse of drugs have important theoretical and clinical significance: such deficits reflect changes to the underlying cortical, sub-cortical and neuromodulatory mechanisms that underpin cognition, and also interfere directly with rehabilitative programs. Recent investigations have been made into the neuropsychology of chronic abuse of cannabis, stimulants and opiates. It is suggested that future progress in this area, involving developing advances in brain-imaging and neuropharmacology, will capitalize on experimental demonstrations of specific patterns of impairments in decision-making, attention and memory function.

Differential effects of cocaine and cocaine alcohol on neurocognitive performance

OBJECTIVE

To investigate the dose-related effects of cocaine with or without alcohol use on the CNS by measuring performance on neurobehavioral tests.

BACKGROUND

Chronic use of cocaine is associated with persistent decrements in cognitive function that are most pronounced in heavy users. Specific neurobehavioral deficits in areas such as executive function and impulsivity would make it difficult for the cocaine abuser to discontinue using drugs. Because alcohol is often used in conjunction with cocaine, the CNS effects of alcohol when taken with cocaine deserve further investigation.

METHOD

The authors evaluated the dose-related effects of cocaine and alcohol use on performance in a variety of neuropsychological tests after 1 to 3 days of abstinence and again after 4 weeks of abstinence. Fifty-six chronic cocaine abusers who had used cocaine during the past 24 to 48 hours volunteered to perform a battery of neuropsychological tests on two separate occasions during a period of enforced abstinence. In addition to using cocaine, most of the volunteers consumed alcohol. Approximately half of the participants consumed more than 10 alcohol-containing drinks per week.

RESULTS

After controlling for the effects of age, sex, and intelligence on performance, the authors found dose-related associations between neurobehavioral performance and cocaine dose and alcohol dose. When the influences of cocaine and alcohol on neurobehavioral performance were taken separately, cocaine and alcohol each selectively affected performance on different neurobehavioral tests after 1 to 3 days of abstinence, with these effects persisting after 4 weeks of abstinence.

CONCLUSION

The concomitant use of cocaine and alcohol may have additive negative effects on the brain as compared to the use of only one of these two substances.

Effects of seasonal allergic rhinitis on selected cognitive abilities

BACKGROUND

Many allergy patients complain of slowed thinking, memory problems, and difficulty sustaining attention during their allergy seasons.

OBJECTIVE

This study evaluated the effect of symptomatic allergic rhinitis on speed of cognitive processing, ability to divide and sustain attention, working memory, and recent verbal memory.

METHODS

Symptomatic ragweed-allergic rhinitis patients and nonatopic control subjects did cognitive testing in, out of, and in ragweed seasons.

RESULTS

Test results indicate that, during ragweed seasons, allergic patients experience subtle slowed speed of cognitive processing but not deficits in attention and recent memory. Some patients also have difficulties in working memory.

CONCLUSIONS

These findings suggest that having allergic reactions to ragweed pollen causes significant cognitive difficulties in a subgroup of patients.