Psychological and neuropsychological effects of adolescent cannabis use: a structured narrative review.

Miazzi R.; Cestonaro C.; Terranova C. · Journal of addictive diseases · 2026

**Background & Methods** This structured narrative review examined psychological and neuropsychological effects of cannabis use during adolescence using human studies identified through MEDLINE/PubMed searches. Fifty-five studies meeting eligibility criteria were included in the analysis, focusing on developmental impacts during this vulnerable period. **Key Findings** • Adolescent cannabis use was frequently associated with increased depressive and anxiety symptoms, psychosis-spectrum experiences, and cognitive impairments including deficits in memory, attention, inhibitory control, and executive functioning. • Neurobiological alterations were documented in multiple brain regions, including abnormalities in cortical maturation, reward-control connectivity, white matter integrity, and neurochemical markers involved in cognition and emotion regulation. • The evidence suggests cannabis exposure during adolescence may contribute to psychological and neurobiological changes, though causal relationships remain difficult to establish definitively. **Dosage & Administration** Not reported. **Safety & Adverse Effects** Adverse effects identified include depressive symptoms, anxiety symptoms, psychosis-spectrum experiences, memory impairment, attention deficits, and inhibitory control dysfunction. Neurobiological adverse effects include alterations in cortical maturation, disrupted reward-control connectivity, compromised white matter integrity, and abnormal neurochemical markers in brain regions governing cognition and emotion regulation. **Evidence Quality** The review is limited by several methodological constraints that reduce causal interpretation. Key limitations include: (1) confounding factors inadequately controlled across studies; (2) polysubstance use complicating attribution of effects to cannabis alone; (3) heterogeneous exposure measurement methods limiting comparability; and (4) differences in study design affecting consistency of findings. While longitudinal and neuroimaging studies provide evidence supporting a possible contributing role of cannabis, the cross-sectional nature of many studies, inability to account for selection bias, and potential reverse causality limit definitive causal conclusions. The authors emphasize that adolescence represents a particularly vulnerable developmental period and recommend prevention strategies and further rigorous longitudinal research to establish causality and clarify mechanisms underlying cannabis-related effects on psychological and neuropsychological development.

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