Cannabis Use during Adolescent Development: Susceptibility to Psychiatric Illness

Benjamin Chadwick,Yasmin L Hurd,Michael L Miller

doi:10.3389/fpsyt.2013.00129

Abstract

Cannabis use is increasingly pervasive among adolescents today, even more common than cigarette smoking. The evolving policy surrounding the legalization of cannabis reaffirms the need to understand the relationship between cannabis exposure early in life and psychiatric illnesses. cannabis contains psychoactive components, notably Δ9-tetrahydrocannabinol (THC), that interfere with the brain’s endogenous endocannabinoid system, which is critically involved in both pre- and post-natal neurodevelopment. Consequently, THC and related compounds could potentially usurp normal adolescent neurodevelopment, shifting the brain’s developmental trajectory toward a disease-vulnerable state, predisposing early cannabis users to motivational, affective, and psychotic disorders. Numerous human studies, including prospective longitudinal studies, demonstrate that early cannabis use is associated with major depressive disorder and drug addiction. A strong association between schizophrenia and cannabis use is also apparent, especially when considering genetic factors that interact with this environmental exposure. These human studies set a foundation for carefully controlled animal studies which demonstrate similar patterns following early cannabinoid exposure. Given the vulnerable nature of adolescent neurodevelopment and the persistent changes that follow early cannabis exposure, the experimental findings outlined should be carefully considered by policymakers. In order to fully address the growing issues of psychiatric illnesses and to ensure a healthy future, measures should be taken to reduce cannabis use among teens.

Highlights

Cannabis sativa is grown worldwide for its production of ∆9tetrahydrocannabinol (THC), a psychoactive compound found in the recreational drugs marijuana and hashish
Research focused on the relationship between cannabis and mental health is important especially considering that psychiatric illnesses are complex disorders with multiple factors contributing to vulnerability and eventual expression of the illness
Escalating doses of THC to adolescent rats decreases sucrose preference, a measure of anhedonia [38]. Other behavioral strategies such as the forced-swim test used to measure depression-related symptoms reveal a pro-depressive phenotype directly associated with adolescent THC [39], these effects generally appear stronger in females [38, 40]. These findings suggest that adolescent cannabinoid exposure could affect the liability to mood disorders later in life, and the potential gender differences may relate in those well-documented in human depression

Summary

INTRODUCTION

Cannabis sativa is grown worldwide for its production of ∆9tetrahydrocannabinol (THC), a psychoactive compound found in the recreational drugs marijuana and hashish. Without significant physiological or mental health impact, is actively debated. These discussions are often not guided by evidence-based data. Based on the accruing data to date outlined in this review, developmental cannabis exposure is an important contributing factor to psychiatric vulnerability (Figure 2A). Determining the long-term impact of occasional and heavy cannabis use during active periods of brain development, such as adolescence, is of critical importance. To provide such insights, data garnered from epidemiological and experimental studies is reviewed in this article. The emerging evidence strongly suggests that cannabis exposure during adolescence increases an adult’s individual vulnerability to drug addiction and schizophrenia and may produce long-lasting effects on anxiety and mood disorders

Adolescent cannabis and psychiatric disorders

Findings

CONCLUSION