An Irish study conducted on 211 adolescents aged between 12 and 15 years has revealed that those adolescents who had experienced childhood trauma were almost five times more likely to use cannabis than those who had experienced trauma. In addition, subjects who had experienced childhood trauma are also five times more likely to develop psychotic symptoms .The researchers also found that the joint presence of cannabis use and childhood trauma increased the likelihood of psychotic symptoms in adolescence to a much greater extent than would be expected if each risk factor was working independently.In Australia, a 20-year follow-up study in young adults exposed to childhood trauma revealed that exposure to multiple traumas, rather than a single major trauma, increases the risk of later psychosis .Based on the Adult Psychiatric Morbidity Survey conducted in England in2007 among 7403 subjects whose mean age was 51.12 years , a multivariate analysis demonstrated that those who had experienced non-consensualsex in childhood were over six times more likely to have had a diagnosis of psychosis compared with those who had not experienced this trauma.
Individuals with a history of non-consensual sexual experience under 16years and cannabis use were over seven times more likely to have been diagnosed with psychosis compared with those without these experiences .The multivariate analysis also indicated that subjects who were unemployed,depressed and who experienced sexual trauma after the age of 16 years were more likely to have had a diagnosis of psychosis . Researchers outlined the fact that the experience of non-consensualsex before the age of 16 years was independently predictive of psychosis diagnosis no matter the presence or absence of cannabis consumption.They suggested that childhood trauma may be one of the more prevailing environmental agents in psychosis onset and development and that cannabis use among individuals diagnosed with psychosis may be attributable, in some cases,to their experiences of childhood trauma . The authors also mentioned that those individuals who experienced both childhood sexual abuse and cannabis use, but who experienced their sexual trauma before they began consuming cannabis, were over four times more likely to have a diagnosis of psychosis.
Alternatively,victims of childhood trauma may simply initiate and continue to use cannabis in a similar way to non-victims but could experience psychosis because an existing emotional,psychological and/or physical vulnerability, potentially attributable to their trauma, has been exacerbated .Finally, the authors concluded that the interaction between cannabis use and childhood trauma suggests that being exposed to these two risk factors acts synergistically in the onset of psychosis and that childhood trauma may advance existing gene-environment conceptualizations of the cannabis-psychosis link. Researchers suggested that the psychosis-inducing effects of cannabis are moderated by an early experience of trauma and that a cross-sensitization between stress and cannabis is responsible in shaping the risk of psychotic outcomes. The possible mechanism by which stress or cannabis use impact on psychosis risk is a sensitization involving an increase of the dopaminergic signaling in the mesolimbic system.
Hyperdopaminergia may be associated with psychosis and the interaction between early life trauma and cannabis may increase the risk for psychosis by bringing about enduring sensitization to dopamine agonists.Finally, the authors stated that their work is the first to demonstrate that even on-severe physical trauma can interact with cannabis on psychosis risk .Their results confirm earlier findings that both cannabis and trauma not only affect psychotic illness but also impact on the broader extended psychosis phenotype in the general population, which represents behavior expression of liability to psychotic disorders . However, they outline that their results do not provide information about to what degree the interaction between cannabis and mal treatment contributes to the onset of new psychotic symptoms or to the persistence of existing symptoms.
Researchers emphasized that there was a strong evidence that childhood trauma was correlated with an increased odds of later life events and cannabis use,and that there was evidence for synergistic effects of trauma and more tentatively recent cannabis use on odds of psychotic experiences, such that the odds were greatest in those exposed to trauma and either life events or cannabis in the past year. They also outlined that the impact of both life events,particularly recent events, and cannabis use on the likelihood of psychotic experiences depends, to a certain degree, on prior exposure to physical and sexual abuse. This is consistent with the hypothesis that childhood trauma creates in some individuals a vulnerability for psychotic experiences which unfolds itself in the event of exposure to further risk factors such as cannabis consumption .