Catechol-o-methyltransferase and plasma monoamine oxidase in patients with affective disorders

No evidence for an association of affective disorders with high- or low-activity allele of catechol-o-methyltransferase gene

Catechol-o-methyltransferase (COMT) is an enzyme that inactivates biologically active or toxic catechols. Previous studies have yielded inconsistent results on the relationship between erythrocyte COMT activity and affective disorders. Recently an amino acid change (Val-108-Met) of the COMT protein was shown to determine high- and low-activity alleles of the enzyme. Using polymerase chain reaction and the restriction enzyme NLaIII, we genotyped 107 patients with bipolar disorder, 62 with unipolar depression, and 121 controls. Neither bipolar nor unipolar patients differ significantly in the genotypic or allelic frequency from the control group. Even when the bipolar and unipolar patients were pooled into a single group, the distributions of both the genotypes and the alleles for the patient group were similar to those for the controls. We conclude that genetic variation that determines high and low activities of COMT does not have a major effect on the vulnerability to affective disorders in our sample.

The decrease of erythrocyte catechol-O-methyltransferase activity in depressed patients and its diagnostic significance

Erythrocyte catechol-O-methyltransferase (COMT) activity was measured in normal and depressed populations before specific medication. In the groups of patients, anxiety and depression scores were evaluated by the AMDP rating scale. The authors found lower enzyme activity in patients with major depression, recurrent and bipolar disorder, depressed, but no change was found in dysthymic disorder when compared to control values. However, there was no relationship between COMT activity and age, anxiety and depression scores of patients. Furthermore, the subdivision into two subpopulations, one with normal COMT activity and another with lower COMT activity, did not make it possible to assign a role to the enzyme in the severity of depression. The enzyme could, however, be considered as a genetic marker of depressive vulnerability.

Studies on biogenic amine metabolizing enzymes (DBH, COMT, MAO) and pathogenesis of affective illness. II. Erythrocyte catechol-O-methyltransferase activity in endogenous depression

Erythrocyte COMT activity was determined in 31 healthy persons (16 men, 15 women) and in 34 persons with endogenous depressive syndrome (12 men, 22 women). It was found that enzyme activity is significantly higher in healthy men than in healthy women. In the group of women with endogenous depressive syndrome COMT activity is elevated as compared with the group of healthy women (P less than 0.05). This is true of all forms of affective disease: bipolar, unipolar, and undifferentiated. High COMT activity in women with depression is apparent mainly in patients whose first and second degree relatives revealed psychiatric disturbances, particularly affective disorders. This supports the significance of the sex factor in the genetic transmission of affective disorders, and a possible involvement of COMT activity changes in the pathogenesis of such disorders in women. No correlation was found between the changes in COMT activity and the psychopathological picture of depression or the severity of endogenous depressive syndrome.

Erythrocyte catechol-O-methyltransferase activity in psychotic twins

Erythrocyte catechol-O-methyltransferase (COMT) activity was analyzed in 20 twin pairs, 6 monozygotic and 14 dizygotic, where one or both twins showed psychotic or prepsychotic symptoms. Fifteen of these pairs, 4 monozygotic and 11 dizygotic, were diagnosed as discordant for serious mental disturbance. The different psychotic states within twins did not seem to be associated with any difference in COMT activity.

Catechol-O-methyltransferase of erythrocytes in patients with endogenous psychoses

A significant decrease in catechol-O-methyltransferase (COMT) activity of erythrocytes was found in both male and female schizophrenic patients, as well as in male patients with schizophreniform psychosis. Among control subjects, a sex difference in COMT activity of erythrocytes was found, with males showing significantly higher activity than females. It is suggested that a genetically determined deficiency of catecholamine degradative enzymes in the central nervous system or, alternatively, influences of nongenetic hormonal factors could be implicated in the findings of altered erythrocyte COMT activity reported.

Erythrocyte COMT-activity in patients with affective disorders

COMT enzyme characteristics (Km, V, ratio of meta/paramethylation) were determined in the red blood cells of 20 patients with endogenous depression, in 20 healthy controls matched as to age and sex, as well as in 10 patients with mania, and 10 patients with neurotic depression. Assessment was done twice, i.e. before and after remission in patients with endogenous depression and in the manic patients. If male and female patients are considered together there was no statistical difference between the COMT characteristics of these patient groups, either before or after remission. Only the bipolar patients showed a higher COMT-activity (V) than their individually matched controls. If however, only the female patients are taken into consideration, COMT-activity of the patients with endogenous depression vs. controls is significantly increased by 60%. This difference can be demonstrated also after remission ("free interval") though statistical significance is reached only for the unipolar group. Further in vitro experiments indicate that antidepressant drugs do not possess a relevant influence on COMT-activity. Ranking the mean COMT-values leads to the following order: matched controls (< neurotic depression < unipolar depression < bipolar depression, which would be in good agreement with theoretical expectations based on the amine hypothesis of depression. Compared with normal male subjects COMT-activity of female controls is significantly lower. On the other hand, the female patients with endogenous depression show a significantly higher enzyme activity than the corresponding male patients.