We sought to determine whether the COMT val158met polymorphism (rs4680) is associated with delusions and hallucinations in people with dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD).
We genotyped rs4680 in a sample of 467 patients affected by bipolar disorder type I with or without a previous illness episode with psychotic features (DSM-IV criteria: delusions or hallucinations).
Carriers of the COMT Val(158)Met Val allele, but not subjects with the Met/Met genotype, showed an increase in hallucinations after cannabis exposure, conditional on prior evidence of psychometric psychosis liability.