The dexamethasone suppression test in dementia

Hyperactivity in the hypothalamic-pituitary-adrenal axis in demented patients with delirium

Occurrence of delirium is known to be related to, among other things, organic brain disorder, somatic disease and old age. It has been hypothesized that delirium is also associated with stress. Disturbances of the hypothalamic-pituitary-adrenal (HPA) system have been found in delirious patients in various studies. The aim of the present study was to determine the activity in the HPA axis in demented patients to ascertain whether the stress regulating system was more disturbed in patients with delirium than in those without delirium. Demented inpatients with no acute medical illness were included in the study. Basal cortisol levels in serum were measured and dexamethasone suppression test (DST) was performed. The most important finding of the study was a strong relationship between delirium and DST pathology irrespective of age and severity of dementia. It is suggested that certain demented individuals have an impaired HPA system and a low delirium threshold and respond to stress with delirium.

The dexamethasone suppression test in dementia: a review of the literature

To examine the utility of the dexamethasone suppression test (DST) in the differential diagnosis of depression in elderly demented patients, we reviewed the literature and focused on four components of this question: (1) cortisol nonsuppression rates in dementia; (2) cortisol nonsuppression and dementia severity; (3) cortisol nonsuppression in demented versus depressed patients; and (4) cortisol nonsuppression following antidepressant treatment. A combined analysis of 27 articles showed cortisol nonsuppression in 60% of patients with concurrent dementia and depression, in 47% of patients with depression only, in 41% of patients with dementia only, in 46% of patients with multi-infarct dementia, in 36% of patients with primary degenerative dementia, and in 10% of controls. The abnormal DST rate in demented patients was not significantly different from the abnormal DST rate in depressed patients. Eight of 12 studies (67%) did not find a significant relationship between DST results and dementia severity dementia patients without depression. Twelve of 13 studies (92%) did not find a relationship between age and DST outcome. The data we reviewed do not support the use of the DST in discriminating between depression and dementia or between dementia subtypes.

Results of dexamethasone suppression test in early Alzheimer dementia

The frequency of an abnormal response to the Dexamethasone Suppression Test (DST) was examined in 24 non-depressed patients in the early stages of Alzheimer dementia. Results were compared with those obtained in 51 geriatric medical inpatients: 15 with major depression, 18 with dysthymic disorder and 18 normal controls. As an abnormal lack of suppression was found in 9 demented patients, in 9 with major depression, 1 with dysthymic disorder and in 2 the normal controls, it appears that DST alone is not useful in distinguishing dementia, even in its early stages, from major depression. In our experience abnormal DST results in demented patients were unrelated to mood.