GROWTH-HORMONE SECRETION IN ALZHEIMERS-DISEASE - 24-HOUR PROFILE OF BASAL LEVELS AND RESPONSE TO STIMULATION AND SUPPRESSION STUDIES

The 24-h growth hormone secretory pattern and GH response to growth ho rmone releasing hormone, the alpha(2)-adrenoceptor agonist clonidine a nd the somatostatin-analogue SMS 201-995 were evaluated in 9 patients with Alzheimer's disease and 9 age- and body mass-matched control subj ects. The secretory profile did not differentiate between patients and controls. Both secreted the largest amount of GH during the early nig hthours between 22.00-02.00, whereas the majority of daytime GH levels were below the assay's detection limit (0.4 ng/ml). No difference was found in GH response to GHRH between patients and controls. All subje cts showed significantly enhanced GH secretion after GHRH. Dividing th e patients into two groups according to age-of-onset (< 60 years >), t here was a trend toward larger GH responses to GHRH for the early-onse t group. No other parameter differentiated the groups. GH levels after clonidine were blunted in all subjects but one AD patient, probably d ue to an age-dependent attenuation frequently observed in subjects ove r 45 years of age. Finally, the administration of the somatostatin-ana logue did not render conclusive results, since spontaneous decline of GH concentration was already beginning 2 hours before the drug was giv en and continued steadily throughout the observation period. In conclu sion, patients with only mild to moderate degree of Alzheimer's diseas e have no prominent changes in GH regulation.