Experimental findings have recently suggested a toxic role for glucocorticoids in hippocampus, the main brain target for the adrenocortical hormones. In this study, we explored the activity of the hypothalamus-pituitary-adrenal (HPA) axis in a group of patients with dementia of the Alzheimer's type (DAT) and in a control group of age-matched subjects. We measured the corticotropin-releasing factor (CRF) levels in cerebrospinal fluid (CSF) and evaluated the plasma cortisol response to a CRF stimulation test. While no differences were observed in the results of the CRF test for two groups, CSF CRF values in DAT patients were found to be significantly higher than in controls. Bearing in mind the bidirectional relationships between the neuroendocrine and immune systems and the changes in some immunological parameters reported in DAT, the possible role of HPA axis hyperactivity in the pathogenesis of primary dementia is discussed.