Classification and Subtypes of Affective Disorders

1. Overview & Epidemiology

Core definitions (Gajdos lecture):

• Mood = a pervasive and sustained feeling tone, experienced internally, that colours the person's behaviour and perception of the world.
• Affect = the external expression of mood (what the examiner observes).
• Sadness / grief are NOT depression — they are normal reactions to loss; grief is culturally shaped and only sometimes pathological.

The fundamental split (memorise this first):

• Unipolar = patient has only major depressive episodes → Major Depressive Disorder.
• Bipolar = patient has manic episodes (alone or with depressive episodes), or hypomanic + depressive episodes.
• **Three "i