To evaluate the clinical and functional effects of cannabis abuse in patients at First Episode Psychosis (FEP) referring to Community Mental Health Centre (CMHC) “Bologna Ovest” and in patients admitted with a diagnosis of psychosis at the Modena Emergency Psychiatry Ward (EPW).

All FEP patients, aged 18-35, referring to CMCH “Bologna Ovest” in a 6-years period were evaluated and followed-up at 3 and 12 months. Of the 1559 psychiatric admissions at the Modena EPW in a 3-year period, those with a positive history for substance abuse were selected.

Among the 88 Bologna Ovest FEPs, 32% were cannabis abusers (FEP-c). In Bologna, FEP-c were more frequently natives (23.39% vs 31.13%; c sq=5.1; p=0.02) single (26.38% vs 0,0% c sq=7.3, p=0.007) and unemployed (13.50% vs 18.32%, c sq=2.4, p=0.1). Non FEP-c did not use any other drug (0.0% vs 26.1%, c sq=77.5; p< 0.001). A trend towards higher prevalence of hospital admission at follow-up was found for FEP-c (4.20% vs 2.4%, c sq=3.8, p=0.07). 22.0% of patients admitted at the Modena EPW had a positive history for substance abuse: of these, 7% were diagnosed with paranoid schizophrenia, which significantly correlated with the use of cannabinoids (alone or in association).

Our results enlighten that cannabis use is frequent among psychotic patients admitted to hospital and worsens clinical course of FEP patients, consistently with previous evidence (Hambrecht & Hafner, 1996; Hafner et al., 2004).

Research mostly conducted in the UK and northern Europe has established that there are high rates of first-episode psychosis (FEP) in large cities and immigrant populations; moreover, psychosis has been found to be associated with cannabis use and early trauma. The present study aimed to evaluate the incidence rate of FEP and the distribution of several risk factors (e.g. age, ethnicity, substance abuse) in Bologna, Italy.

The Bologna FEP (BoFEP) study is an 8-year prospective study. All FEP patients, 18–64 years old, consecutively referred to the West Bologna Community Mental Health Centre (CMHC) from 2002 to 2009 were evaluated. Sociodemographic information, migration history and clinical data were collected through an ad-hoc schedule. Psychiatric diagnoses were recorded using the Schedule for Clinical Assessment of Neuropsychiatry (SCAN).

The overall incidence rate (IR) in the BoFEP study was 16.4 per 100 000 person-years [95% confidence interval (CI) 13.9–18.9]. The incidence was higher in young people, men and migrants (MI).

The IR of FEP found by the Bologna study is lower than that found by other European studies. However, as in other studies, the incidence was higher in certain groups. This heterogeneity has implications for policy and mental health service development, and for understanding the aetiology of psychosis.

People who use cannabis have an increased risk of psychosis an effect attributed to the active ingredient δ9-tetrahydrocannabinol (Δ9-THC). There has recently been concern over an increase in the concentration of Δ9-THC in the cannabis available in many countries.

To investigate whether people with a first episode of psychosis were particularly likely to use high-potency cannabis.

We collected information on cannabis use from 280 cases presenting with a first episode of psychosis to the South London & Maudsley National Health Service (NHS) Foundation Trust, and from 174 healthy controls recruited from the local population.

There was no significant difference between cases and controls in whether they had ever taken cannabis, or age at first use. However, those in the cases group were more likely to be current daily users (OR = 6.4) and to have smoked cannabis for more than 5 years (OR = 2.1). Among those who used cannabis, 78% of the cases group used high-potency cannabis (sinsemilla, ‘skunk’) compared with 37% of the control group (OR 6.8).

The finding that people with a first episode of psychosis had smoked higher-potency cannabis, for longer and with greater frequency, than a healthy control group is consistent with the hypothesis that Δ9-THC is the active ingredient increasing risk of psychosis. This has important public health implications, given the increased availability and use of high-potency cannabis.