The shock therapies act likewise on the hypothalamic balance. Physiological experiments and clinical observations have shown that these procedures influence the hypothalamically controlled hypophyseal secretions and increase sympathetic discharges. They shift the hypothalamic balance to the sympathetic side. This explains the beneficial effect of electroshock therapy in certain depressions and a shift in the reaction from hypo -- to normal reactivity of the sympathetic system as shown by the Mecholyl test. Some investigators have found a parallelism between remissions and return of the sympathetic reactivity of the hypothalamus to the normal level as indicated by the Mecholyl test and, conversely, between clinical impairment and increasing deviation of this test from the norm. Nevertheless, the theory that the determining influence of the hypothalamic balance has a profound influence on the clinical behavior of neuropsychiatric patients has not yet been tested on an adequate number of patients. The Mecholyl and noradrenalin tests applied with certain precautions are reliable indicators of this central autonomic balance, but for the sake of correlating autonomic and clinical states, and of studying the effect of certain therapeutic procedures on central autonomic reactions, additional tests seem to be desirable.

It was assumed that the shift in autonomic hypothalamic balance occurring spontaneously in neuropsychiatric patients from the application of certain therapeutic procedures follows the pattern known from the sleep wakefulness cycle. A change in the balance to the parasympathetic side leads in the normal individual to sleep or, in special circumstances, to cardiovascular collapse or nausea and vomiting. In both conditions the emotional and perceptual sensitivity is diminished, but no depression occurs such as is seen clinically or may be produced in normal persons by drugs. The fundamental differences between physiological and pathological states of parasympathetic (and also of sympathetic) dominance remain to be elucidated.