The effects of naturalistic cannabis use on cognition and subjective experience in older adults with normal cognitive function
P. di Ciano, B. Le Foll, S. Zhao, P. Byrne, Y. Elzohairy, J. Brubacher, M. McGrath, B. Brands, S. Chen, W. Wang, P. Kaduri, C. Wickens, T. Rajji
Journal of Psychopharmacology November 3, 2025 DOI: 10.1177/02698811251370975 via Semantic Scholar
Summary
AI-generated from the abstractOlder adults aged 65–78 who smoked their preferred legal cannabis with an average THC content of 18.7% showed decreased performance on the trail making test (versions A and B) 60 minutes after smoking, compared to when they were sober. However, the percentage of words retained in a verbal free recall test was significantly higher after cannabis, apparently due to a reversal in performance decrement. Smoked cannabis produced robust subjective drug effects. Correlations between blood THC levels and cognitive performance at 60 and 210 minutes were unclear. The findings suggest that older adults who use cannabis may show decrements on only some cognitive tests, along with marked changes in subjective experience.
Study at a glance
| Characteristics | Naturalistic study with counterbalanced crossover design Peer reviewed |
|---|---|
| Sample size | 31 |
| Population | Adults aged 65–78 with normal cognitive function |
| Intervention | smoked cannabis |
| Dose | average THC content of 18.7% |
| Duration | 60 minutes and 210 minutes post-smoking |
| Keywords | Medicine Psychology |
| Key finding | Older adults who smoked cannabis showed decreased performance on the trail making test but improved word retention in a verbal free recall test, compared to a sober condition. |
Abstract
Background: Adults over the age of 65 years are the fastest growing group of cannabis users, but there are few studies of the acute effects of cannabis in this population. Aims: In the present naturalistic study, participants were invited to smoke their preferred legal cannabis in the lab prior to tests of verbal learning and memory, executive function and information processing, and functional vision and visual attention. Methods: In this counterbalanced, crossover design, performance after cannabis was compared to a sober condition. Blood levels of delta-9-tetrahydrocannabinol (THC) were measured and correlated with cognition. Results: Participants aged 65–78 (31 in total; 21 male) with normal cognitive function chose to smoke cannabis with an average THC content of 18.7%. Analysis with linear mixed models found that performance on the trail making test versions A and B was decreased 60 minutes after smoking cannabis, compared to the no cannabis condition. The percentage of words retained in the verbal free recall test was significantly higher in the cannabis condition; this was apparently due to a reversal in performance decrement. Smoked cannabis produced robust subjective drug effects. At 60 and 210 minutes, there were unclear correlations of blood THC and metabolites to cognitive performance. Conclusions: These results suggest that older adults who use cannabis may show decrements in performance on only some tests of cognition, and marked changes in subjective experience.