[Mechanisms of development of recurrences in endogenous psychoses. Duration of remission in affective psychoses].

A study was made of 755 remissions in 171 patients suffering from affective psychoses. It has been established that distributions of the duration of complete remissions designed according to small (week and two-week) intervals are of periodic nature. This attests to rhythmical fluctuations of the risk of a relapse. Mathematic methods of analysis of the time series enable one to establish the polyrhythmic structure of the fluctuations, in which the leading rhythms are those with the intervals lengths of the order of 2, 5, 9, 12-13 and 22 weeks. These data well agree on the whole with the findings obtained earlier for schizophrenia remissions.