Pref. -Assoc. S. A. Sukhanov. Cyclothymia and manic-depressive psychosis. Medical newspaper. 1910 No. 16-17

Cyclothymia, says Dr. Sukhanov, is the result of a congenital anomaly in the structure of the central nervous system. It is revealed by the change of periods of oppression of mental activity by periods of its acceleration and better mood. Finding sometimes in childhood, cyclothymia goes and proceeds in a fatal way; it makes itself felt throughout the life of the individual. If the periods of inhibition and acceleration of mental activity do not go beyond certain limits in their manifestations, then they speak of neurasthenia or consider such a person healthy, and sharper manifestations of the cyclothymic constitution are usually diagnosed as mania or melancholia. The author considers cyclothymia to be a mild form of manic-depressive psychosis.