Sometimes it is more “inward anxiety and trembling,” a painful tension; sometimes it is an anxious restlessness, which finds an outlet in the most varied gestures, in states of violent excitement, and in heedless attempts at suicide. These moods are most frequently found in the periods of transition between states of depression and mania; they are, therefore, probably most correctly regarded as mixed states of depression and manic excitability (Kraepelin, 1913).

The inner unrest is the constant thing, while the motor unrest is variable (Lewis, 1934).

Introduction

The greatest shortcoming of psychiatry is the near complete lack of knowledge of the pathophysiological processes underlying our clinical entities. Kahlbaum (1863) was the first to distinguish clearly between symptomatic clinical pictures and the disease process that was responsible for them. Kraepelin took this concept a step further and based the idea of the disease process (Vorgang) on the conditions under which the disease starts, its course, and outcome. This method of clinical psychiatry achieved the separation of manic-depressive illness from dementia praecox. But the real identity of the pathophysiological process underlying the clinical entities still remains obscure. Our psychiatric nosology is entirely based on phenomenology and course.

We do, however, have important tools at our disposal, which are the psychoactive drugs. The response to these drugs not only indicates the pharmacological action of the drug itself but also provides important clues about the nature of the neuropathologic process upon which the drug acts.