Neuroendocrine studies in dementia patients: responses of plasma GH and PRL following bromocriptine administration

Bromocriptine stimulates growth hormone (GH) secretion at the hypothalamus and suppresses prolactin (PRL) secretion at the pituitary level. We administered bromocriptine to 30 patients with dementia of the Alzheimer type (DAT), 30 patients with multi-infarct dementia (MID) and 22 age matched healthy controls, and compared response patterns of GH and PRL. Incomplete PRL suppressive responses (suppression rate < 50%) were seen in 36.7% of DAT patients and in 30.0% of MID patients, indicating that both groups had the same degree of pituitary dysfunctions. Blunted GH responses (< 5 ng/ml) were seen in 93.3% of DAT patients, in 63.3% of MID patients and in 31.8% of the controls. The results indicate that neuroendocrine regulation of GH is more selectively and severely damaged in DAT patients than in MID patients at the hypothalamus.