Cannabis-induced psychiatric disorders

Cannabis is one of the most widely consumed substances. Numerous investigations suggest a correlation between long-term cannabis use and the development of mental health disorders. In this regard, it has been estimated that cannabis use is implicated in approximately 50% of psychiatric disorders, mainly, but not only, psychosis or schizophrenia.

Research has not been able to clarify the causal relationship between cannabis and psychiatric disorders, although it is true that overlapping symptomatology has been identified between the primary diseases themselves and prolonged use.

It has now been suggested that the action of THC, the main psychoactive compound in cannabis on the cannabinoid system, may produce neurobiological changes that would give rise to different manifestations similar to those of psychiatric disorders. A possible involvement of the cannabinoid receptors on which THC exerts its effect has also been identified, in particular CB2 receptors and mechanisms, as well as an impairment on the NMDA system involved in the capacity to make neuronal connections, learning and memory, mediated by the action on CB1 cannabinoid receptors. A relationship has also been observed with the increase of dopamine in certain areas of the brain due to THC consumption that would alter the maturation of the dopaminergic system, involved in directly regulating motor function, cognition, motivation and emotional processes.

In addition to the neurobiological causes as such, other risk factors have been identified as candidates to contribute to the development of psychiatric disorders:

  • Consumption in early age given that it may affect neurodevelopment involving the cannabinoid receptor system.
  • Concurrent presence of other psychiatric conditions.
  • Use of other substances of abuse.
  • Other psychosocial factors such as childhood trauma or urban upbringing, especially among males associated with low social fragmentation have also been suggested as risk factors.

Symptoms

It has historically been associated with fewer negative symptoms and more mood-related symptoms than primary psychiatric disorders. The mood symptom profile includes obsessive ideation, interpersonal sensitivity, depression and anxiety. The presence of social phobia is significant and hypomania and agitation are more pronounced. Visual hallucinations are more common and there is greater awareness of the clinical state, and the ability to identify symptoms as a manifestation of substance use. The presence of positive symptoms decreases much more rapidly after abstinence from substance use.

Prevention

Given that a causal relationship has not been clarified, it is difficult to establish preventive measures for psychiatric disorders beyond avoiding the use of cannabis and other substances of abuse, including alcohol, especially if there is a personal or family history of a psychiatric disorder. In the latter case, it is recommended to attend the periodic check-ups recommended by the corresponding physician.

Number of observed variants

13.5 million variants

Number of risk loci analyzed in the study

8 loci

Bibliography

Rentero D et al. Cannabis-induced psychosis: clinical characteristics and its differentiation from schizophrenia with and without cannabis use. Addictions. 2021 Mar 31;33(2):95-108.

Shrivastava A et al. Cannabis and psychosis: Neurobiology. Indian J Psychiatry. 2014;56(1):8-16.

Ruby S et al. Cannabis-Induced Psychosis: A Review. Psychiatric Times 2017; 34 (7).

Pasman JA et al. GWAS of lifetime cannabis use reveals new risk loci, genetic overlap with psychiatric traits, and a causal influence of schizophrenia. Nature Neuroscience. 2018 Sep;21(9):1161-1170.

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