MedWire News: Premorbid conduct disorder symptoms are significantly associated with cannabis use among patients with a first episode of psychosis, research shows.
"Early cannabis use has consistently been associated with an increased risk for the later development of psychosis [and] studies suggest that conduct disorder is more common amongst young people who later go on to develop psychosis," explain Charlotte Malcolm (King's College London, UK) and team.
To investigate whether there is a link between cannabis use and premorbid conduct disorder symptoms in psychosis patients, the researchers recruited 38 women and 64 men, aged 18-65 years, who were receiving treatment for a first episode of psychosis.
All of the participants were interviewed about their use of cannabis using the Cannabis Experience Questionnaire. They were also assessed for the occurrence of conduct disorder symptoms before the age of 15 years using the Antisocial Personality/Conduct Disorder module of the Structured Clinical Interview for DSM-IV.
In total, 20 (19.6%) patients experienced three or more symptoms of conduct disorder before the age of 15 years, with a higher prevalence of non-aggressive than aggressive symptoms.
All of the patients with conduct disorder symptoms reported using cannabis at some point in their lives, compared with just 60% of those who did not experience conduct disorder symptoms.
Analysis revealed that cannabis use before the age of 14 years was significantly associated with conduct disorder symptoms, at an odds ratio of 1.46 compared with no use, after accounting for stimulant/hallucinogen use and level of education.
They also found that the number of conduct disorder symptoms experienced before the age of 15 years was independently associated with lifetime cannabis use in a dose-response manner, with each conduct disorder symptom associated with a 5.41-fold increased risk of ever having used cannabis.
Malcolm and team conclude in the journal Schizophrenia Research: "The present study supports the hypothesis that, among persons experiencing their first episode of psychosis, conduct disorder symptoms prior to age 15 were positively associated with both lifetime cannabis use and cannabis use before age 14.
"To our knowledge, this is the first study to show that conduct disorder symptoms may be linked to the development of psychosis by an increased likelihood of early cannabis use."
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