cannabis and psychosis

cannabis and psychosis The association between substance misuse (cannabis however they impose a considerable personal and public health burden (Degenhardt Regier et al. 1990). This Comorbidity as a result largely enhances cost associated with treatment, predominantly in relation to hospital and other institutional services. The majority of the evidence regarding prevalence of substance use and mental illness comes from the United States, though European standpoint on prevalence is rapidly rising. One of the first and most famous US study is The Epidemiological Catchment Area study conducted by Regier et al. 1990 across 5 US sites, which involved over 20.000 participants. This study tried to measure how common dual diagnosis was and stated that 47% of the participants they surveyed with schizophrenia or schizophreniform disorder also met the criteria for substance use disorder/dependence at some point in their life. Furthermore, the likelihood of having substance use disorder amongst patients with psycho tic illness was notably higher compared to those in the general population without a psychotic illness (Kessler et al. 1994; Regier et al. 1990). In sharp contrast, studies that have been conducted in the UK have reported more moderate rates of substance misuse amongst those with psychotic disorders. For instance, Cantwell in 2003 undertook a study with 316 patients with schizophrenia and only 7% had stated that they had a problem with substance misuse in the previous year, and 21% had reported problematic use some time before that (Cantwell, 2003). Similarly, Wright and Colleagues identified patients with psychotic illnesses who had been in contact with services in the London Borough of Croydon and reported that prevalence rates of dual diagnosis were 33% for the use of any substance and lifetime history of any illicit drug use was 35% of the sample (Wright et al. 2000). Cannabis is the most frequently used substance in patients with psychotic disorder (Van Mastrigt et al. 2004; Ba rnett et al. 2007) and the literature indicates fairly consistently the association between regular uses of cannabis and developing first-onset psychosis[1] (Grech et al. 2005). However, the causes for the links are still hotly debated. Nevertheless, cannabis has damaging effects on the course of the illness on top of being an economic burden on health services (Atakan, 2009). More specifically, estimates of frequency of cannabis abuse amongst patients with first-episode psychosis is said to range from 20% to 70% (Miles et al. 2003; Isaac et al. 2005). A systematic review of 53 treatment samples and 5 epidemiological studies looking at the prevalence of cannabis use and misuse among those with psychotic illnesses stated lifetime use in 42% and lifetime misuse in 22.5% of the sample while current use was 23% and misuse 11.3% (Green et al. 2005). Furthermore, epidemiological studies also have shown that cannabis is the most frequently abused substance amongst younger people (Van Mastr igt, 2004; Addington Wade et al. 2007) with lower educational background (Mueser et al. 1990) and it is more common in men than in women amongst first-episode psychosis patients (Barnett et al. 2007; Addington Barnes et al. 2006). Inevitably, cannabis abuses among youth experiencing a first-episode psychosis results in negative consequences for prognosis and relapse and therefore complicate treatment and impair recovery (Archie et al. 2009). It is constantly reported in the literature that patients with first-episode psychosis who abuse cannabis had considerably more hospital admissions rates as well as more psychotic symptoms compared to first episode psychosis patients who do not abuse cannabis (Wade et al. 2006; Negrete et al. 1986; Turkington et al. 2009)