Psychosomatic Medicine 11:30-44 (1949)
© 1949 American Psychosomatic Society

Effect of Chronic Fear on the Gastric Secretion of HCl in Dogs

¹ Department of Psychology, Institute of Human Relations, Yale University

A review of the literature concerned with specific psychologic processes involved in the etiology of peptic ulcer revealed a confusing array of contrasting proposals resulting from personality studies of ulcer patients. Of these proposals, that which emphasized the primary role of chronic fear or anxiety appeared to be the best substantiated one.

Experimental evidence shows that vagal discharge and associated increased gastric acidity plays a primary role in the physiologic mechanism of ulcer formation.

From the foregoing, one would predict a positive relation between chronic fear behavior and gastric acidity. This prediction was not adequately supported experimentally and it is contradictory to Cannon's hypothesis that increased sympathetic discharge is associated with inhibited parasympathetic discharge in the emotional response of fear.

This study was performed to obtain direct experimental evidence relevant to these two hypotheses: a) during a state of chronic fear behavior, the acidity of the gastric contents is higher than during normal behavior; b) if persistent fear behavior occurs over an extended period of time, peptic ulcers will develop. It was also desirable to measure gastric emptying rate, heart rate, and behavioral changes under these two conditions of behavior.

A modified conditioning procedure was used to develop a state of chronic fear in 7 dogs. Behavioral observations revealed that 6 of these dogs developed chronic fear behavior and at the same time showed increased gastric acidity, gastric emptying rate, nonresting heart rate, and increased variability of both nonresting and resting heart rates. The dog who failed to develop chronic fear behavior was the only exception to this pattern of autonomic changes. Removal of the animals from the experimental environment or omission of the reinforcing pain stimulus resulted in recovery of these behavioral, gastric, and cardiac changes. Evidence showed that increased acidity occurs during conditioned fear in the absence of the primary experience of pain. No sexual difference was found in the acid response to the induction of chronic fear.

Gross and histologic examination of the stomach and duodenum of each dog showed no signs of tissue pathology in any case.

The implication of these results for the problem of ulceration in humans was discussed. In addition, they indicated that the direct extension of Cannon's hypothesis to chronic emotional states, which are of basic importance in psychosomatic disorders, is not justified.