COURSE

MDI is an illness where episodes and intervals alternate in cycles, sometimes with a regular pattern.

The cycle of MDI is made of episodes and intervals and they cannot be separated and studied apart, as they constitute the basic unity of this illness. The longitudinal (long-term) observation of MDI in each person can reveal patterns of recurrence, clarify the relationship of episodes to psychosocial or pharmacological or environmental stressors and guide short- and long-term treatment.

Manic/hypomanic and Depressive episodes are present in a majority of patients, but in a minority of cases only manic symptoms are present (Unipolar Mania).

Recurrent episodes of depression with mild hypomanic periods can be easily misdiagnosed as Recurrent (Unipolar) Depression.

An interval is defined as a period of four weeks or longer without symptoms. In some cases the intervals only last days or hours so that the illness seems to run a continuous and uninterrupted course.

We distinguish between a Continuous Cycling and an Intermittent Course based on the absence or presence of intervals.

In Continuous Cycling there are no intervals between episodes. The episodes can follow a long-cycles course or a rapid-cycles course. In the intermittent forms there are symptom-free intervals and the sequence of intervals and episodes can be evaluated. The distinction between Mania-Depression-Interval (M-D-I) and Depression-Mania-Interval (D-M-I) can be made in some cases.

Kukopoulos initially reported a positive response to lithium among those patients with Mania-Depression-Interval more often than in those with Depression-Mania-Interval. This finding has been replicated by several studies in independent groups of patients.

Regular Irregular
Intermittent Continuous
M-D-I Long Cycles
D-M-I Rapid Cycles
Seasonal

Patterns of recurrence can sometimes be recognized: some patients suffer from seasonal recurrences of Mania and/or Depression (Faedda), others only experience episodes every few years or in response to specific precipitants (i.e. post-partum).

Some patients have four or more episodes in the course of a year, a course of illness defined as Rapid-Cycling by Dunner and Fieve.

When the number of episodes per year is more than four but less than 365, the course is described as Ultra-Rapid Cycling. If the number of episodes per year is equal or greater than 365, the course is described as Ultradian Cycling. These are commonly observed in children and adolescents (Geller) or among some adult patients treated with antidepressants (Altshuler).