As part of an investigation to determine the relationship between stress tolerance and the development of senile psychosis, the authors measured the effect of ACTH, administered intramuscularly, on the plasma and urinary corticoids in 30 normal aged persons and 32 patients with senile psychosis. The patients tended to have higher plasma corticoid levels and lower urinary corticoid amounts per gram creatinine, but the differences were not statistically significant. The authors suggest that the greater response of patients with senile psychosis to physical and psychological stress might be due to pituitary or hypothalamic dysfunction rather than to a difference in corticoid output, and further investigation of these possibilities seems warranted.Abstract Teaser