FORMS OF MDI

“The modes of mania are infinite in species, but one alone in genus…”
-Aretaeus

Several attempts were made at defining subtypes of MDI based on severity of symptoms, recurrence rate and phases of illness. For example, the most common forms have the following features:
 Mania alternating with severe to mild depression (MD or Md), also called Bipolar I.
 Depression alternating with mild Mania or Hypomania (Dm) also called Bipolar II.
 Hypomania alternating with mild Depression or Cyclothymia.
 Recurrent Depression with antidepressant-induced Hypomania is often referred to as Bipolar III.
 Recurrent Depression with Hyperthymia, or a family history of Mood disorders is sometimes called Bipolar IV
For a review of different subtypes of MDI see an excellent review by Akiskal.

Traditionally Mania has been considered the defining feature of MDI. It must be clearly understood that the majority of forms of MDI do not present with Mania but rather with Hypomania and other excitatory symptoms rarely severe enough to be clinically prominent. Even depressive phases might be the result of excitatory phenomena, as postulated in 1861 by Griesinger:

“By using the expression ‘psychic depressive states’ we did not mean to imply that the basic nature of these states is inactivity and weakness ... We have much more reason to assume that very intense states of irritation of the brain and excitation of the psychic processes are very often the cause of such states. But the end result…as far as mood is concerned is a state of depression