The Action of Autonomic Drugs on Normal Persons and Neuropsychiatric Patients

Abstract

Summary In experimental studies on cats it has been shown in this laboratory that simple autonomic tests reveal the state of excitability of the hypothalamus. The degree of the hypotensive action of Mecholyl indicates the state of sympathetic hypothalamic excitability, whereas the pulse-slowing reflex induced by the rise of the systolic blood pressure upon intravenous injection of norepinephrine indicates the state of parasympathetic hypothalamic excitability. The application of these tests in normal persons and neuropsychiatric patients shows: The sympathetic excitability declines progressively with increasing age in normal individuals and mental patients. This decline is independent of changes in the blood pressure level since it occurs in groups of persons whose mean blood pressure is practically the same in the three age groups studied. In view of the considerable influence exerted by the age factor on the sympathetic excitability indicated by the Mecholyl test, a comparison between normal persons and groups of patients is valid only when similar age groups are compared. Significant differences exist between the control and the mental group under these conditions. At all ages the sympathetic hyperreactors and hyporeactors are in the majority in the group of mental patients, whereas they are in a minority in the control group. Sympathetic hyporeactors are present in schizophrenics at the age of 25 and less but are absent in the control group. Somatic therapy is recommended in functional mental disorders with the view to restoring physiological autonomic excitability at the hypothalamic level. This recommendation is based on four groups of data showing that (a) the Mecholyl test indicates sympathetic reactivity at the hypothalamic level; (b) autonomic changes indicated by the reaction to Mecholyl are paralleled by changes in behavior (Funkenstein et al.); (c) procedures such as electroshock, which according to the physiological analysis increase central sympathetic reactivity, benefit patients who are sympathetic hyporeactors but not sympathetic hyperreactors; (d) procedures such as the inhalation of high concentrations of carbon dioxide, which has been shown to diminish the reactivity of the sympathetic division of the hypothalamus and the intensity of the hypothalamic-cortical discharge, are beneficial in the treatment of sympathetic hyperreactors but are contraindicated in the case of sympathetic hyporeactors. Statements c and d refer to the clinical work of Funkenstein et al.²⁴ and Moriarty,³¹ respectively, and the physiological work elucidating the nature of the Mecholyl test. The therapeutic effect of carbon dioxide therapy was predicted in 1953.⁶ The quotient Maximal rise of the systolic blood pressure/Maximal diminution of the heart rate following the intravenous injection of 0.005 mg. norepinephrine has been used as an indicator of parasympathetic hypothalamic excitability, since physiological work showed the dependence of this quotient on the excitability of the anterior hypothalamus. This quotient showed variations too great to permit the recognition of any differences between the control group and the neuropsychiatric group. However, the work showed that the parasympathetic reactivity declines in the normal and abnormal groups with increasing age. Increasing age is, therefore, associated with a decrease in sympathetic and parasympathetic central reactivity. Whether the state of autonomic balance changes with increasing age cannot yet be said.