Recreational Substance Use is Linked to Deficits in Recall, but Not Recognition Memory

Recreational substance use is thought to disrupt neurotransmitter systems involved in memory. While prior research consistently reports recall impairments among people with a history of substance use, findings on recognition memory remain mixed. Importantly, most studies relied on single-task assessments, limiting the ability to capture a comprehensive picture of memory performance in this population. This study assessed various memory processes (i.e., free recall, cued recall, item recognition, and source recognition) in individuals with and without a history of recreational substance use to identify which aspects of memory are more vulnerable to substance use.

The sample consisted of 100 subjects: 47 people without a history of illicit substance use (27 females, age range from 18 to 50+) and 53 with a history of illicit substance use (21 females, age range from 18 to 50+). Participants completed self-report questionnaires and lab-based memory tasks.

Individuals with a history of substance use performed significantly worse than those without a history of substance use in the California Verbal Learning test. Moreover, higher frequencies of substance use were associated with poorer performance, suggesting a dose-response relationship between substance use and verbal learning. On the contrary, there were no significant differences between the groups in the Source Memory, False Memory and Verbal Paired Associates tests. Most results remained significant after adjusting for covariates (e.g., general health, sleep routine, alcohol use and age).

This study provides compelling evidence that recreational substance use has a detrimental effect on memory, particularly impacting free recall abilities, while recognition memory remains relatively unaffected.