The combination of childhood sexual trauma and early cannabis use significantly increases the risk of psychosis multiplicatively compared to the individual factors alone.
Summary
Large community sample (NCS); binary logistic regression; interaction between early cannabis use (<16 years) and childhood sexual trauma on clinically recorded psychosis diagnoses: interaction term OR=6.93 (95%-CI 1.39–34.63, p=.02); in adolescents with early cannabis use (<16 y.), risk from sexual trauma rose to OR=11.96 (95%-CI 2.10–68.22, p=.01). No significant main effect for cannabis alone.
P
PopulationAdults from the US general population (National Comorbidity Survey), n not explicitly stated
I
InterventionEarly cannabis use (under 16 years) in combination with childhood sexual trauma
O
OutcomeSignificant interaction between early cannabis use and childhood sexual trauma on psychosis diagnosis (OR=6,93, 95%-CI=1,39–34,63, p=0,02); in persons with cannabis use under 16 years and sexual trauma OR=11,96 (95%-CI=2,10–68,22, p=0,01)
Confidence in the evidence
Very lowLowModerateHigh
Moderate
The third of four GRADE levels, the effect estimate is probably reliable.
Quality profile
Sample size—
Blinding—
Effect sizeClear benefit
Citations / year★★★★★
Authors
Houston JE, Murphy J, Adamson G, Stringer M, Shevlin M.
Previous research investigating the etiology of psychosis has identified risk factors such as childhood sexual abuse and cannabis use. This study investigated the multiplicative effect of these variables on clinically assessed diagnoses of psychosis based on a large community sample (the National Comorbidity Survey). Demographic variables (sex, age, urbanicity, ethnicity, education, employment, and living arrangements) and depression were used as predictors in the first block of a binary logistic regression. In the second block, the variables representing early cannabis use, childhood sexual trauma, and the interaction between these variables were entered. There was no significant main effect for early cannabis use or childhood sexual trauma. The interaction was statistically significant (odds ratio [OR] = 6.93, 95% confidence interval [CI] = 1.39-34.63, P = .02). The effect for the sexual trauma variable was statistically significant for those who used cannabis under 16 years (OR = 11.96, 95% CI = 2.10-68.22, P = .01) but not for those who had not used cannabis under 16 years (OR = 1.80, 95% CI = 0.91-3.57, P = .09). Many factors have been shown to be significant in the etiology of psychosis; however, the current research augments previous findings by examining psychosis in terms of an interaction between 2 of these factors.