sentences:  Today's leading conceptual thinker in the area of bipolar subtyping, Akiskal is a fastidious researcher and an astute clinical observer.He is a devotee of Emil Kraepelin; he believes that the nosologic (classification) pendulum is gradually swinging back towards Kraepelin's original unitary concept of the bipolar spectrum of mood disorders (Lieber, Arnold).Professor Akiskal rose to prominence with his integrative theory of depression.