Catechol-O-methyltransferase gene polymorphism is associated with risk of psychosis in Alzheimer Disease

There is emerging evidence that psychosis in Alzheimer Disease (AD) represents a clinically relevant phenotype with a distinct biological process. It has been reported that a functional polymorphism of the catechol-O-methyltransferase (COMT) gene predisposes to an increased risk for schizophrenia and likely to psychosis susceptibility. Aim of this study was to evaluate functional COMT genetic variation as a risk factor for psychosis in Alzheimer Disease. One hundred eighty-one AD patients and 208 age-matched controls underwent clinical and neuropsychological examination, behavioural and psychiatric disturbances evaluation, and ApoE and COMT genotyping. The distribution of COMT genotypes did not significantly differ in AD compared to controls. Among patients with psychosis (32.6%), 88.1% were COMT*H carriers (COMT H/H or COMT H/L, p.01). The Odds Ratio (OR) for risk of psychosis in COMT*H carriers was 2.66 (confidence interval, CI 95%: 1.6-6.62), taking into account possible confounding factors. A comparable influence of COMT polymorphism on psychosis over the course of the disease was reported. These findings suggest that COMT polymorphism influences on the risk of psychosis since the early stages, and claims for the possibility to identify distinct phenotypes on genetic basis among AD patients.