MedWire News: In patients presenting with a first episode of psychosis (FEP), cannabis use in the previous year is associated with a more acute onset of illness, study results suggest.
Researchers Rodolfo Mazzoncini (University of Verona, Italy) and colleagues were able to analyze those who had only used cannabis, thus “disentangling the confounding effect of polydrug use.”
The study aimed to assess if a history of substance use, particularly cannabis, is associated with a more problematic presentation in FEP, in terms of social adjustment, access to the services, and mode of onset.
Mazzoncini and colleagues identified 468 individuals from the Aetiology and Ethnicity of Schizophrenia and Other Psychoses (AESOP) study who presented to UK health services with a FEP between 1997 and 1999.
Information on substance use in the previous year was obtained using the Schedules for Clinical Assessment in Neuropsychiatry (SCAN) and modified Personal and Psychiatric History Schedule (PPHS), which also includes information on substance use from a relative or carer, and the clinical case notes.
The overall prevalence of any drug use was 45%. The most commonly used illicit substance was cannabis, with a prevalence rate for the previous year of 42%, followed by amphetamines (12%), hallucinogens (9%), cocaine (8%), opiates (3%), sedatives and barbiturates (1%), and other drugs (1.0%).
In the general UK population, the prevalence rate is 11% for any drug use and 9% for cannabis use, the researchers note.
Sociodemographic factors associated with drug use at FEP were unemployed status (odds ratio [OR]=2.25) and living in a non-self-owned property (OR=2.26).
Due to the sample size the researchers were able to analyze cannabis use alone. They found that use of the drug was associated with a more acute mode of illness onset, after adjustment for age, gender and ethnicity (OR=2.03).
“Our results therefore suggest the importance of studying accurately the impact of each single illicit substance class on the onset and outcome of psychotic illnesses,” Mazzoncini et al conclude.
The research is published in the journal Acta Psychiatrica Scandinavica.
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