TRH test, DST, and response to desipramine in primary degenerative dementia

The relationship of primary degenerative dementia (PDD) to major depressive disorder (MDD) is important clinically and theoretically. Neuroendocrine challenge strategies in PDD have focused primarily on the hypothalamic-pituitary-adrenal axis, have had varied results, and have not been coupled with assessment of response to antidepressant therapy. We studied the Thyrotropin-Releasing Hormone (TRH) test, the Dexamethasone Suppression Test (DST), and response to desipramine in 12 patients with PDD and 10 patients with MDD. The PDD patients had a high percentage of abnormal TRH tests and DSTs. This was not associated with improvement on desipramine.