Abstract
Specific questioning and frequent observation of a 69 year-old woman with cyclic bipolar manic-depressive illness showed that she had disturbances of thirst, appetite, bowel and bladder function and dramatic changes in body weight, in association with different phases of her mental illness. Examination of one manic phase under constant diet and inpatient control showed cardiovascular changes, sodium retention, body weight gain, with raised aldosterone secretion but steady vasopressin. There appears to be a sub-group of manic-depressive patients with evidence of disturbed hypothalamic functions as part of their mental illness, as shown particularly by changes in water and electrolyte metabolism.