Dependent cocaine users consistently display cognitive deficits but cognitive performance of recreational cocaine users has rarely been investigated.
To examine whether cognitive performance is ...impaired in relatively pure recreational and dependent cocaine users.
The cognitive performance of recreational (n = 68) and dependent cocaine users (n = 30) was compared with the performance of stimulant-naive controls (n = 68) employing an extensive neuropsychological test battery. Moreover, the impact of attention-deficit hyperactivity disorder (ADHD) symptoms, craving and early age at onset was analysed.
Dependent cocaine users display broad cognitive impairments in the domains of attention, working memory, declarative memory and executive functions. The performance of recreational cocaine users in all four domains was intermediate between that of controls and dependent users and they displayed significant deficits foremost in the domains of attention and working memory. In addition, ADHD symptoms, craving and age at onset were important modulators of cognitive function in cocaine users.
Cognitive deficits occur at a recreational and non-dependent level of cocaine use. Cocaine use and ADHD seem to have mutually aggravating effects on cognitive impairment.
Persistent dose-related cognitive decrements have been reported in 28-day abstinent heavy marijuana (MJ) users. However, the neural substrates of these decrements in cognitive performance are not ...known. This study aimed to determine if 25-day abstinent MJ users show persistent dose-related alterations in performance and brain activity using PET H
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15O during the Iowa Gambling Task-IGT (a decision-making task). Eleven heavy MJ users and 11 non-drug users participated. The MJ group resided in an inpatient research unit at the NIH/NIDA-IRP for 25 days prior to testing to ensure abstinence. A dose-related association was found between increased MJ use and lower IGT performance and alterations in brain activity. The MJ group showed greater activation in the left cerebellum and less activation in the right lateral orbitofrontal cortex (OFC) and the right dorsolateral prefrontal cortex (DLPFC) than the Control group. When the MJ group was divided into Moderate (8–35 joints/week) and Heavy users (53–84 joints/week), the Heavy MJ group showed less activation in the left medial OFC and greater activation in the left cerebellum than the Moderate group. However, brain activity and task performance were similar between the Moderate MJ users and the Control group, suggesting a “threshold effect”. These preliminary findings indicate that very heavy users of MJ have persistent decision-making deficits and alterations in brain activity. Specifically, the Heavy MJ users may focus on only the immediate reinforcing aspects of a situation (i.e., getting high) while ignoring the negative consequences. Thus, faulty decision-making could make an individual more prone to addictive behavior and more resistant to treatment. Finally, it is unclear if these neurologic findings will become progressively worse with continued heavy MJ use or if they will resolve with abstinence from MJ use.
Many studies have suggested that adolescence is a period of particular vulnerability to neurocognitive effects associated with substance misuse. However, few large studies have measured differences ...in cognitive performance between chronic cannabis users who started in early adolescence (before age 15) with those who started later.
To examine the executive functioning of individuals who started chronic cannabis use before age 15 compared with those who started chronic cannabis use after 15 and controls.
We evaluated the performance of 104 chronic cannabis users (49 early-onset users and 55 late-onset users) and 44 controls who undertook neuropsychological tasks, with a focus on executive functioning. Comparisons involving neuropsychological measures were performed using generalised linear model analysis of variance (ANOVA).
The early-onset group showed significantly poorer performance compared with the controls and the late-onset group on tasks assessing sustained attention, impulse control and executive functioning.
Early-onset chronic cannabis users exhibited poorer cognitive performance than controls and late-onset users in executive functioning. Chronic cannabis use, when started before age 15, may have more deleterious effects on neurocognitive functioning.
Abstract Decision-making deficits are a robust cognitive correlate of substance abuse, but few studies have addressed the long-term differential associations of cocaine use and marijuana (MJ) use on ...decision-making. This study utilized the Iowa Gambling Task (IGT), a widely used measure of decision-making, to investigate the relationship between cocaine and MJ use and IGT learning. We analyzed between and within group differences across two consecutive testing sessions in abstinent users of either MJ or cocaine. We assessed long-term correlates of the use of these drugs by evaluating users after 25 days of enforced abstinence. Results showed that both cocaine users and MJ users performed worse than controls on the total IGT net score. All groups showed learning between Session 1 and Session 2, but the cocaine users showed the smallest increase in performance. The pattern of learning from the beginning to the end (block × block) of the IGT (Session 2) was different for the drug groups, with the cocaine group showing more learning than the MJ group. Dose-related measures of cocaine use (g/week) and MJ use (joints/week) predicted IGT performance (the heavier the drug use the lower the performance). Differential correlates of cocaine use and MJ use on decision-making learning may have important implications for the development of novel treatment interventions.
Abstract Substance-dependence is highly associated with executive cognitive function (ECF) impairments. However, considering that it is difficult to assess ECF clinically, the aim of the present ...study was to examine the feasibility of a brief neuropsychological tool (the Frontal Assessment Battery — FAB) to detect specific ECF impairments in a sample of substance-dependent individuals (SDI). Sixty-two subjects participated in this study. Thirty DSM-IV-diagnosed SDI, after 2 weeks of abstinence, and 32 healthy individuals (control group) were evaluated with FAB and other ECF-related tasks: digits forward (DF), digits backward (DB), Stroop Color Word Test (SCWT), and Wisconsin Card Sorting Test (WCST). SDI did not differ from the control group on sociodemographic variables or IQ. However, SDI performed below the controls in DF, DB, and FAB. The SDI were cognitively impaired in 3 of the 6 cognitive domains assessed by the FAB: abstract reasoning, motor programming, and cognitive flexibility. The FAB correlated with DF, SCWT, and WCST. In addition, some neuropsychological measures were correlated with the amount of alcohol, cannabis, and cocaine use. In conclusion, SDI performed more poorly than the comparison group on the FAB and the FAB's results were associated with other ECF-related tasks. The results suggested a negative impact of alcohol, cannabis, and cocaine use on the ECF. The FAB may be useful in assisting professionals as an instrument to screen for ECF-related deficits in SDI.
Elevated cortisol indicates stress and may be a risk factor for cognitive decline in aging. Genetic factors may influence individual vulnerability to the adverse effects of stress on cognitive ...function in aging.
The authors investigated whether the gene-environment interaction between the genotype for the apolipoprotein E gene (APOE) and cortisol predicted cognitive performance in older urban adults. Cross-sectional data were analyzed from a population-based sample of 50-70-year-old men and women. Cognitive performance, salivary cortisol levels, and APOE genotype were assessed in 962 subjects. Scores on 20 standard cognitive tests were combined into seven domain scores (language, processing speed, eye-hand coordination, executive functioning, verbal memory and learning, visual memory and learning, visuoconstruction).
In adjusted models, while a higher cortisol level was associated with worse cognitive scores, the slopes of the adverse relations were steeper in persons with at least one APOE-epsilon4 allele. Effect sizes were large: for example, the effect of having one epsilon4 allele plus a cortisol area under the curve greater than the 75th percentile was equivalent to a decrease in language score expected from an age increase of 8.0 years (95% confidence interval=1.7-14.4), while having two epsilon4 alleles and a cortisol area under the curve greater than the 75th percentile was equivalent to an age increase of 33.4 years (95% CI=14.8-52.0).
These data suggest that APOE genotype modifies cortisol's relations with cognitive functioning and that the epsilon4 allele increases vulnerability of the aging brain to adverse effects of stress.
We used PET
15O and a modified version of the Stroop task to determine if 25-day abstinent heavy marijuana (MJ) users have persistent deficits in executive cognitive functioning (ECF) and brain ...activity. Performance on a modified version of the Stroop task and brain activity was compared between 25-day abstinent, heavy marijuana users (
n = 11), and a matched comparison group (
n = 11). The 25-day abstinent marijuana users showed no deficits in performance on the modified version of the Stroop task when compared to the comparison group. Despite the lack of performance differences, the marijuana users showed hypoactivity in the left perigenual anterior cingulate cortex (ACC) and the left lateral prefrontal cortex (LPFC) and hyperactivity in the hippocampus bilaterally, when compared to the comparison group. These results suggest that marijuana users display persistent metabolic alterations in brain regions responsible for ECF. It may be that marijuana users recruit an alternative neural network as a compensatory mechanism during performance on a modified version of the Stroop task. These differences in brain activity may be a common denominator in the evolution of maladaptive behaviors such as substance abuse and other neuropsychiatric disorders.
Marijuana is the most widely used illicit substance in the United States; however, previous imaging studies have not detected altered brain structure in marijuana users compared to non-users. ...Voxel-based morphometry was used to investigate possible differences in brain tissue composition in a group of 11 heavy marijuana users and a group of 8 non-users. All participants were male. Statistical comparisons were made at the voxel level on T1-weighted magnetic resonance images to determine differences in gray matter and white matter tissue density. Compared to non-users, marijuana users had lower gray matter density in a cluster of voxels in the right parahippocampal gyrus (
P = 0.0001), and greater density bilaterally near the precentral gyrus and the right thalamus (
P < 0.04). Marijuana users also had lower white matter density in the left parietal lobe (
P = 0.03), and higher density around the parahippocampal and fusiform gyri on the left side compared to non-users (
P < 0.002). Longer duration of marijuana use (in years) was significantly correlated with higher white matter tissue density in the left precentral gyrus (
P = 0.045). Our preliminary results suggest evidence of possible structural differences in the brain of heavy marijuana users, and localize regions for further investigation of the effects of marijuana in the brain.
Cocaine abusers exhibit impairment of executive cognitive functions that are mediated by the frontal cortex. This work tested for structural (i.e., tissue composition) abnormalities that may underlie ...such performance deficits. Research participants were cocaine abusers (
n = 14) abstinent for 20 days and a non-drug-using comparison group (
n = 11), who underwent magnetic resonance imaging (T1-weighted scans of the brain). Gray matter and white matter tissue densities were determined using voxel-based morphometry with small volume correction based on a priori hypotheses derived from functional imaging of the same subjects. Cocaine abusers had significantly lower gray matter tissue density than did the non drug users in 10 of 13 small volumes analyzed in the frontal cortex bilateral anterior cingulate gyrus (infragenual and perigenual regions) and medial orbitofrontal cortex and the lateral orbitofrontal cortex and middle/dorsal cingulate gyrus in the right hemisphere. No group differences were found in white matter density of the frontal cortex. These results extend our previous findings of defective frontal cortical activation (indexed by cerebral blood flow) in cocaine abusers to include abnormalities in gray matter tissue density in the same frontal cortical regions.
To determine if recently abstinent, heavy marijuana (MJ) users show differences in polysomnographic (PSG) measures compared with a drug-free control group.
A group of carefully selected heavy MJ ...users were chosen for study inclusion and matched to a drug-free control group. Questionnaire data were collected prior to cessation of MJ use. PSG studies were conducted during 2 consecutive nights after discontinuation of MJ use in our core sleep laboratory.
Baltimore Maryland, General Clinical Research Center (GCRC) core sleep lab.
17 heavy MJ users discontinuing MJ use and 14 drug-free controls. Men and women were studied, 18 to 30 years. The MJ users reported no other drug use and alcohol use was negligible in both groups. Urine was positive for metabolites of cannabis only.
The MJ users showed differences in PSG measures (lower total sleep times, and less slow wave sleep than the control group) on both nights; they also showed worse sleep efficiency, longer sleep onset, and shorter REM latency than the control group on Night 2. More sleep continuity parameters were significantly worse for the MJ group than the control group on Night 2 versus Night 1, indicating that sleep in the MJ group was relatively worse on Night 2 compared to Night 1. The MJ group did not show improved sleep after an adaptation night as expected. Withdrawal symptoms, craving, and depression did not appear to influence these findings.
During discontinuation of heavy MJ use, PSG measures of sleep disturbance were detected in MJ users compared with a drug-free control group. While this preliminary study cannot identify the extent to which these group differences were present before abstinence, poor sleep quality either prior to or after MJ discontinuation could result in treatment failure for MJ users. Further investigation is necessary to determine the association between the use and cessation of MJ and sleep disturbance.
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