Personality, cognitive, and neuropsychological correlates of harmful alcohol consumption: a cross-national comparison of clinical samples

Bidirectional causality between addiction and cognitive deficits

Cognitive deficits are highly comorbid with substance use disorders. Deficits span multiple cognitive domains, are associated with disease severity across substance classes, and persist long after cessation of substance use. Furthermore, recovery of cognitive function during protracted abstinence is highly predictive of treatment adherence, relapse, and overall substance use disorder prognosis, suggesting that addiction may be best characterized as a disease of executive dysfunction. While the association between cognitive deficits and substance use disorders is clear, determining causalities is made difficult by the complex interplay between these variables. Cognitive dysfunction present prior to first drug use can act as a risk factor for substance use initiation, likelihood of pathology, and disease trajectory. At the same time, substance use can directly cause cognitive impairments even in individuals without preexisting deficits. Thus, parsing preexisting risk factors from substance-induced adaptations, and how they may interact, poses significant challenges. Here, focusing on psychostimulants and alcohol, we review evidence from clinical literature implicating cognitive deficits as a risk factor for addiction, a consequence of substance use, and the role the prefrontal cortex plays in these phenomena. We then review corresponding preclinical literature, highlighting the high degree of congruency between animal and human studies, and emphasize the unique opportunity that animal models provide to test causality between cognitive phenotypes and substance use, and to investigate the underlying neurobiology at a cellular and molecular level. Together, we provide an accessible resource for assessing the validity and utility of forward- and reverse-translation between these clinical and preclinical literatures.

Neurocognitive profiles of people with comorbid depression and alcohol use: implications for psychological interventions

Depression and alcohol use disorders frequently co-occur and are highly prevalent. Both conditions are known to impair cognitive functioning, yet research into the role of these impairments in response to Cognitive Behaviour Therapy (CBT) is limited. The purpose of the present study was to examine the relationship between baseline neuropsychological performance, severity of depressive symptoms and alcohol use disorders. Participants with current depression and hazardous alcohol use were functioning in the average range on all neuropsychological measures prior to treatment entry. Baseline measures of drinking severity and a range of cognitive functions were inversely correlated. After controlling for other baseline variables, superior baseline cognitive functioning predicted greater reductions in depression severity after 17 weeks. These predictive effects occurred across both brief and extended interventions. Findings suggest that improvement in depression following psychological treatment is enhanced by greater fluid reasoning ability and is predicted by executive functioning, regardless of the treatment length or problem focus.

Comorbidity implications in brain disease: Neuronal substrates of symptom profiles

The neuronal substrates underlying aspects of comorbidity in brain disease states may be described over psychiatric and neurologic conditions that include affective disorders, cognitive disorders, schizophrenia, obsessive-compulsive disorder, substance abuse disorders as well as the neurodegenerative disorders. Regional and circuitry analyses of biogenic amine systems that are implicated in neural and behavioural pathologies are elucidated using neuroimaging, electrophysiological, neurochemical, neuropharmacological and neurobehavioural methods that present demonstrations of the neuropathological phenomena, such as behavioural sensitisation, cognitive impairments, maladaptive reactions to environmental stress and serious motor deficits. Considerations of neuronal alterations that may or may not be associated with behavioural abnormalities examine differentially the implications of discrete areas within brains that have been assigned functional significance; in the case of the frontal lobes, differential deficits of ventromedial and dorsolateral prefrontal cortex may be associated with different aspects of cognition, affect, remission or response to medication thereby imparting a varying aspect to any investigation of comorbidity.

The use of the mini-mental state examination in recruitment for substance abuse research studies

BACKGROUND

Substance abuse is associated with cognitive impairment. Participation in clinical addiction research can be cognitively demanding. Screening tools can identify cognitively impaired subjects. We examined the use of the mini-mental state examination (MMSE) as an entry criterion in three randomized controlled substance abuse clinical trials.

METHODS

In each of the three studies, we calculated the proportion of subjects excluded due to MMSE scores (<21) suggestive of cognitive impairment. We estimated the potential impact on enrollment based on the number of excluded subjects. Separately, for two of the studies, we assessed the impact of cognitive function on participation in follow-up using multivariable logistic regression.

RESULTS

Of all persons screened for enrollment, 1.6% (171/10,791) were ineligible based solely on a MMSE score of <21. We estimate that 119 of these 171 ineligible persons would have consented and enrolled. These 119 persons would have represented 9.3% of all enrolled subjects across these studies. For subjects in a study in an inpatient detoxification unit, a higher MMSE score was associated with higher odds (adjusted odds ratio 1.15, 95% CI 1.03-1.30) of completing at least one follow-up assessment. A similar impact on subject follow-up was not observed in a study of medical inpatients with unhealthy alcohol use (adjusted odds ratio 1.01, 95% CI 0.86-1.20).

CONCLUSION

Screening for cognitive impairment using the MMSE excludes a small, but substantial, number of persons from addiction research studies. Cognitive ability, as captured by the MMSE may impact follow-up. These data support cognitive screening of substance abuse research subjects.

IS THERE COGNITIVE IMPAIRMENT IN CLINICALLY ‘HEALTHY’ ABSTINENT ALCOHOL DEPENDENCE?

AIMS

The aim of this study was to determine neuropsychological performance in apparently cognitively, mentally, and physically healthy abstinent alcohol-dependent subjects compared with control subjects who were recruited for a number of different neuroimaging studies.

METHODS

All subjects completed a battery of neuropsychological tests as part of the neuroimaging protocol.

RESULTS

The group dependent on alcohol performed as well as controls on a non-verbal memory test and verbal fluency but performed worse in the verbal memory task, Trail A + B, and total IQ derived from Silverstein's short-form of the WAIS-R. However, the IQ performance of both groups was above average. In both groups, age was associated with slower performance on the Trail A + B task. In the alcohol-dependent group, severity of dependence and length of abstinence was not associated with performance of any task.

CONCLUSIONS

In this apparently clinically healthy population of abstinent alcohol-dependent subjects, frontal lobe dysfunction was detectable using the Trail A + B and digit symbol tasks. This was despite above-average WAIS-R IQ scores. Consideration needs to be given to routine incorporation of cognitive testing in alcohol dependence since subtle deficits may not be easily apparent and may impact on treatment outcome.

Short-term neuropsychological recovery in clients with substance use disorders

BACKGROUND

Cognitive impairments are frequently observed in clients who enter treatment programs for substance abuse. The potential for early recovery of cognitive abilities is suggested by previous research; however, the extent of improvement and risk factors that may help predict individual differences in rates of recovery remain unclear. This study is a 6-week follow-up and retest of an original sample of 197 men and women who had received a broad neuropsychological assessment at addiction treatment entry. The aim was to examine the potential clinical significance of changes in cognitive functioning and the extent to which differential recovery was predictable from client background information.

METHODS

Fifteen neuropsychological tests were readministered to 169 of 197 clients 6 weeks after treatment entry. Structural equation modeling was used to estimate separately the practice effects and recovery in four cognitive domains: executive function, memory, information processing speed, and verbal ability. Client background information included age, sex, education, substance use and consequences, psychopathology, medical problems, familial alcoholism history, and childhood behavior problems.

RESULTS

A four-factor model of latent neuropsychological ability that was previously identified at treatment entry was replicated at follow-up. Statistically significant increases in the means of the four latent abilities were found. Memory showed a medium effect size improvement. Executive function, verbal ability, and information processing speed, however, showed only small effect size improvements, suggesting limited clinical significance. Substance use between treatment entry and follow-up, antisocial personality disorder, negative use consequences, less education, and medical problems were modestly predictive of less recovery.

CONCLUSION

Cognitive recovery in the first 6 weeks of treatment is possible, but, with the possible exception of memory, improvement may be minor in terms of clinical relevance.

Screening Cognitive Impairment in Alcohol Abusers

1. Studies have reported various neuropsychological abnormalities in people with excessive drinking patterns and associated problems with the assessment and treatment of this group. 2. The aim of this study was to assess the potential of a screening instrument to help detect the presence of cognitive impairment in excessive alcohol users undergoing detoxification. 3. The Memory Screening Test has potential as a screening instrument to assess clients' cognitive ability to benefit from psychoeducational material.

Drinking-related assessment instruments: cross-cultural studies

In recent years a number of drinking-related assessment instruments have undergone extensive developmental work and are in widespread use. These include measures that are designed to assess: 1) patterns of alcohol consumption. Timeline Followback Method (TLFB); and 2) antecedents to alcohol use, Inventory of Drinking Situations (IDS)-two constructs that would be expected to be sensitive to cross-cultural variability in drinking practices. These assessment tools present opportunities for the study of cross-cultural differences in drinking patterns and the circumstances under which drinking occurs. A World Health Organization project utilizing these assessment tools is currently underway in five countries (Australia, Canada, Mexico, Poland, and Sweden). This project focuses on the identification of profile differ.

Single photon emission computed tomography with iodoamphetamine-123 and neuropsychological studies in long-term abstinent alcoholics

Ten long-term abstinent alcoholics (mean abstinence = 7.7 years) were compared with 13 recently detoxified substance-dependent inpatients (mean abstinence = 25 days) and 8 nonalcoholic control subjects on global end regional measures of cortical cerebral blood flow (CBF), and on neuropsychological measures. CBF was assessed using 123iodoamphetamine (IMP) single photon emission computed tomography (SPECT) under conditions of behavioral challenge (Raven's Progressive Matrices). CBF and neuropsychological test performance were worse in the recently detoxified inpatients. Of greater interest, there was a dissociation in the long-term abstinent group, which, while neuropsychologically indistinguishable from controls, showed significantly decreased mean cortical IMP uptake. We conclude that there may be persistent physiologic abnormalities in long-term abstinent alcoholics who have achieved full behavioral recovery. Smoking on the day of SPECT scanning was also identified to be a significant confound to understanding CBF changes in alcoholism.

Alcoholic cognitive deterioration and nutritional deficiencies

Chronic alcoholic patients frequently exhibit a mild to moderate cognitive impairment that has been related to Wernicke-Korsakoff encephalopathy and attributed tentatively to nutritional and vitamin deficiencies. To elucidate the possible relation between alcoholic cognitive deterioration (ACD) and nutritional and vitamin deficiencies, several tests of intelligence and memory were administered to 54 chronic alcoholic patients and 30 controls. Serum levels of thiamine, folic acid, vitamins B12, A, and E, and certain nutritional indexes were determined in most of the subjects. The alcoholics scored significantly lower in intellectual and visuospatial tasks but not in verbal memory tasks. They had a lower serum level for thiamine but not of the remaining vitamins. However, the correlations between serum thiamin and cognitive performance scores were low, and according to stepwise regression analysis, duration of alcohol intake and education were the variables with predictive value for intellectual and memory test performance. These results suggest that serum thiamin deficiency is not the main pathogenetic factor related to ACD.

Reduced performance in tests of memory and visual abstraction in seamen exposed to industrial solvents

Eighty-five seamen exposed to a variety of organic solvents and hydrocarbon compounds during their work on chemical tankers were compared with 59 unexposed seamen. Visual memory, auditory memory and visual abstraction were examined 14 days or more after the last solvent exposure. Multivariate analyses were performed to control the effects of confounding factors such as age, alcohol consumption, smoking, cerebral concussions and educational level. Significant correlations were found between increasing solvent exposure and poor results in tests of auditory memory and visual abstraction. These results indicate adverse psychological effects caused by chronic organic solvent exposure.