Cross-sectional and longitudinal associations of cannabis use with cognitive functioning in individuals with a Cannabis Use Disorder: the moderating role of nicotine

Background and Aims. Cannabis is among the most widely used psychoactive substances globally and is often consumed alongside nicotine. Cannabis use has been associated with impairments in attention, learning, and memory, whereas nicotine can acutely enhance, but chronically impair, certain cognitive functions. However, most studies examine cannabis in isolation, leaving the cognitive impact of nicotine co-use unclear. This study aimed to estimate differences in cognitive performance between individuals with cannabis use disorder (CUD) and healthy controls, to determine whether cognition relates to heaviness of cannabis use or CUD symptom severity, to test moderation by daily nicotine use, and to assess whether baseline cognition predicts cannabis outcomes one year later. Design. Cross-sectional and one-year longitudinal study. Setting. The Netherlands and Texas, USA. Participants. A total of 231 participants aged 18-30 participated: 130 with CUD (57.7% male) and 101 controls (43.6% male). Measurements. Participants completed tasks assessing interference control, attentional bias, sustained attention, executive functions, emotion recognition, delayed recall memory, working memory, and IQ. Primary outcomes were cognitive task scores; predictors included heaviness of cannabis use, CUD symptom severity, and daily nicotine use. Findings. Compared with controls, individuals with CUD performed worse on interference control (p < .001), immediate recall memory (p = .009), delayed recall memory (p = .013), executive functions (p = .016), estimated IQ (p < .001). Within the CUD group, cognitive performance was unrelated to heaviness of use or CUD severity. Before correction, daily nicotine use moderated the link between CUD severity and working memory (p = .011), with poorer performance observed only among non-nicotine users. Lower attentional bias (p = .027) and sustained attention (p = .023) modestly predicted greater CUD severity at one-year follow-up. Conclusions. CUD was associated with deficits in several cognitive domains independent of use intensity or severity. Nicotine co-use related to relatively better working memory, and attention-related cognition showed limited predictive value for later CUD outcomes.