Discrepancies between subjective and objective cognition in persons with multiple sclerosis: Exploring the role of cannabis use.

Background: Cannabis is frequently used among people with multiple sclerosis (pwMS). Prior research within the MS population revealed detrimental effects of cannabis use on objective measures of cognitive performance.

Aim: To investigate associations between cannabis use, perceived cognitive deficits, and discrepancies between self-reported and assessed cognitive abilities.

Methods: Objective cognitive performance and subjective perceptions of cognitive functioning were assessed in a cross-sectional study of 847 pwMS (254 cannabis users, 593 non-users). Linear regression analyses were conducted to explore whether cannabis use independently predicted (1) perceived cognitive deficits, and (2) differences between self-reported and assessed cognitive functioning (i.e., discrepancy score), while including anxiety, depression, fatigue and premorbid IQ as covariates.

Results: Analyses revealed significant associations between cannabis use and subjective cognitive impairment, with users reporting greater perceived deficits than nonusers, [F(5823) = 348.59, p < .001, adjusted R2 = 0.63]. Moreover, cannabis use independently predicted cognitive discrepancy scores, [F(5598) = 83.87, p < .001, adjusted R2 = 0.41], indicating a greater tendency for users to overestimate their cognitive dysfunction.

Conclusion: These results provide first insights into the association of cannabis use with metacognition in pwMS. Clinicians and researcher should consider testing for cannabis use when assessing patients for cognitive impairments.