DIAGNOSIS

“Manic-depressive insanity…(includes) certain slight and slightest colourings of mood, some of them periodic, some of them continuously morbid, which on the one hand are to be regarded as the rudiment of more severe disorders, on the other hand pass without sharp boundary into the domain of personal predisposition. In the course of the years I have become more and more convinced that all the above mentioned states only represent manifestations of a single morbid process.”
-Kraepelin

The diagnosis of MDI is based on several factors:
• Symptoms
• Family History of a Mood Disorder or Substance Abuse
• Course of Illness
• Response to Treatment

Many illnesses and drugs can produce symptoms of Mania, Hypomania or Depression and need to be distinguished and adequately treated. The most common causes are listed in the Differential Diagnosis Section.

It is almost always possible to find a history of Mood Disorders or Substance Abuse/Dependence among relatives of subjects with MDI. However, the extraordinary variability of symptom caused by MDI and the common failure to diagnose non-classic or milder forms of MDI can interfere with documenting a family history of Mood Disorders. For example: a parent or relative might suffer from pathological gambling or have a criminal history, common examples of poor impulse control.
These forms are very often undiagnosed and untreated, and rarely their connection with MDI is recognized.

The presence of cycling or recurrences of mood instability, the continuous or recurrent instability of mood and activity are quite distinctive of MDI. It is the constant change that appears to be the only constant in the variable course of this illness. For this reason, the observation of these symptoms, over time, might be the only way to document a recurrent course of illness. This was well known since antiquity and has been emphasized by Kraepelin in his seminal work on MDI.

The beneficial response to mood stabilizing agents confirms the diagnosis. The induction of hypomanic or manic symptoms with stimulants, antidepressants and other substances has been considered evidence of a ‘latent’ form of MDI, requiring an external precipitant to become apparent.