Recollective experience in alcohol dependence: a laboratory study

Substance abuse and susceptibility to false memory formation: a systematic review and meta-analysis

Background

Substance abuse has an impact on various cognitive domains, including memory. Even though this impact has been extensively examined across different subdomains, false memory has been sparsely studied. This systematic review and meta-analysis seek to synthesize the current scientific data concerning false memory formation in individuals with a history of substance abuse.

Methods

PubMed, Scopus, the Cochrane Library, Web of Science, and PsycINFO were searched to identify all experimental and observational studies in English, Portuguese, and Spanish. Studies were then examined by four independent reviewers and, if they met the inclusion criteria, assessed for their quality. The Cochrane Risk of Bias Tool for randomized controlled trials (RCT) and the Joanna Briggs Institute (JBI) critical appraisal checklists for quasi-experimental and analytic cross-sectional studies were used to assess the risk of bias.

Results

From the 443 screened studies, 27 (and two more from other sources) were considered eligible for full-text review. A final 18 studies were included in the present review. Of these, 10 were conducted with alcoholics or heavy drinkers, four focused on ecstasy/polydrug users, three were done with cannabis users and one focused on methadone maintenance patients with current cocaine dependence. Regarding false memory type, 15 studies focused on false recognition/recall, and three on provoked confabulation.

Conclusions

None but one of the studies considering false recognition/recall of critical lures found any significant differences between individuals with a history of substance abuse and healthy controls. However, most of the studies taking into account false recognition/recall of related and unrelated events found that individuals with a history of substance abuse showed significantly higher rates of false memories than controls. Future research should continue to consider different types of false memories as well as their potential association with relevant clinical variables.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=266503, identifier: CRD42021266503.

Impairments in learning by monetary rewards and alcohol-associated rewards in detoxified alcoholic patients

BACKGROUND

Excessive alcohol consumption has been linked to structural and functional brain changes associated with cognitive, emotional, and behavioral impairments. It has been suggested that neural processing in the reward system is also affected by alcoholism. The present study aimed at further investigating reward-based associative learning and reversal learning in detoxified alcohol-dependent patients.

METHODS

Twenty-one detoxified alcohol-dependent patients and 26 healthy control subjects participated in a probabilistic learning task using monetary and alcohol-associated rewards as feedback stimuli indicating correct responses. Performance during acquisition and reversal learning in the different feedback conditions was analyzed.

RESULTS

Alcohol-dependent patients and healthy control subjects showed an increase in learning performance over learning blocks during acquisition, with learning performance being significantly lower in alcohol-dependent patients. After changing the contingencies, alcohol-dependent patients exhibited impaired reversal learning and showed, in contrast to healthy controls, different learning curves for different types of rewards with no increase in performance for high monetary and alcohol-associated feedback.

CONCLUSIONS

The present findings provide evidence that dysfunctional processing in the reward system in alcohol-dependent patients leads to alterations in reward-based learning resulting in a generally reduced performance. In addition, the results suggest that alcohol-dependent patients are, in particular, more impaired in changing an established behavior originally reinforced by high rewards.