GROWTH HORMONE SECRETION IN PRIMARY DEGENERATIVE DEMENTIA: CORRELATIONS WITH COGNITIVE IMPAIRMENT

Abstract

Changes in brain peptides and neurotransmitters are thought to elicit alterations of growth hormone (GH) secretion in dementia. Baseline GH levels and hormone responses to GH-releasing hormone (GHRH)—administered alone or after pyridostigmine pretreatment—were evaluated in 17 patients, aged 52–83, with primary degenerative dementia quantified by the Clinical Dementia Rating (CDR) Scale and the Mini-Mental State Examination (MMSE) with a view to detecting correlations between neuroendocrine and clinical data. Basal GH levels were not statistically different in patients and in age-matched controls. However, when patients were split into the three CDR groups of disease severity, basal GH levels were significantly higher in those with more severe dementia than in all other patients and in controls. GH responses to GHRH, evaluated both in terms of peaks attained after simulation and of secretion areas under the curve (AUC), were significantly higher in patients than in controls after pyridostigmine pretreatment, but not after the infusion of GHRH alone. Patients with mild to moderate dementia had GH peaks after GHRH higher than more severe patients. Pyridostigmine did not potentiate GHRH effects in the more severe cases. The scores on Rey's 15-word test for memory function were directly correlated with GH peaks after GHRH. No correlations were found between GH data, age, body weight, disease duration and scores at other psychometric assessments such as MMSE, Raven's matrices, verbal fluency or WAIS tests.