Psychoses in twins. A 10 year clinical and biochemical follow-up study

An unbiased sample of monozygotic and dizygotic twins with psychotic or pre-psychotic symptoms has been followed during a 10 year period. The sample was based on 9000 patients, both born in 1930-1946, and hospitalized in Scania, Sweden, during the 1960s. 23 complete pairs were examined in 1972 with regard to a variety of clinical, genetic, and biochemical parameters. A fairly young sample was chosen in order to include a sufficient number of discordant pairs to be followed prospectively, thus making it possible to study a group of individuals with a very high risk of developing psychosis. 18 of the 23 pairs were re-examined by the same clinician 10 years later. The biochemical methods were both partly the same as those used 10 years earlier and partly extended. Very few changes in the clinical diagnoses of the twins were noted during the follow-up period. A highly significant correlation was found between 1972 and 1982 activity both for catechol O-methyltransferase (COMT) and for monoamine oxidase (MAO). The basal levels of MAO, COMT, dopamine beta-hydroxylase (DBH) and serotonin (5-HT) did not show correlations to the presence of pre-psychotic or psychotic symptoms.