Biological Correlates of the Congruence and Incongruence of Psychotic Symptoms in Patients with Type 1 Bipolar Disorder

We examined the catechol-O-methyl transferase (COMT) Val108/158Met genotype in 160 type 1 bipolar patients. We also analyzed the plasma concentrations of homovanillic acid (HVA), 3-methoxy-4-hydroxyphenylethylenglycol (MHPG) and 3,4-dihydroxyphenylacetic acid in 60 of those patients who had been without mood stabilizers or neuroleptic treatment for at least 8 days. Results: Patients with congruent psychotic symptoms presented a higher plasma concentration of HVA than mood incongruent psychotic patients. The Val/Val genotype was associated with higher plasma concentrations of HVA and MHPG. We detected a larger proportion of patients with psychotic symptoms in the Val/Val genotype group, although this did not reach statistical significance. It was found that the distribution of the COMT genotype was not influenced by the congruent/incongruent nature of the psychotic symptoms. Limitations: The proportion of patients without psychotic symptoms in our sample was low. This fact limits the value of some comparisons. Conclusions: Congruent and incongruent psychotic patients can be distinguished in terms of the concentration of plasma HVA. Based on the presence or absence of mood incongruent symptoms, the Val108/158Met polymorphism of the COMT gene alone does not appear to be a crucial determinant in the division of psychotic bipolar patients. Nevertheless, COMT polymorphisms may influence some of the characteristics of the patients by their effect on monoamine metabolism. Copyright (c) 2008 S. Karger AG, Basel