Young Adults With Cannabis Use Disorder Have Lower Verbal IQ But No Other Cognitive Deficits

CUD participants had significantly lower IQ with a strong effect size (p < .001, d = 0.862), driven specifically by lower verbal IQ. This finding survived adjustment for education years. No other cognitive domains showed significant differences, and neither problematic use severity nor dosage was associated with cognition.

Cross-sectional study of 115 young adults (83 with CUD, 32 controls, ages 18.5-32.5). Comprehensive cognitive battery assessed executive function, working memory, episodic memory, verbal reasoning, attention, and IQ. All analyses accounted for alcohol/nicotine use and trait anxiety.

The selective verbal IQ deficit is striking because it survived correction for education and was not accompanied by impairments in other domains. This specificity suggests cannabis use disorder may affect certain aspects of language-mediated intelligence while leaving other cognitive functions intact in young adults.

Combined with the companion study showing preserved social cognition, a pattern emerges: CUD in young adults may selectively affect verbal intellectual capacity while sparing social understanding, executive function, and memory. This targeted profile differs from the broad cognitive decline often assumed.

Cross-sectional design cannot determine whether lower verbal IQ preceded or resulted from CUD. Pre-existing verbal IQ differences could predispose individuals to CUD rather than cannabis causing IQ decline. The non-treatment-seeking sample may not represent more severe CUD.