THE CONTRIBUTION OF HYPERCORTISOLEMIA TO THE COGNITIVE DECLINE OF GERIATRIC DEPRESSION

Cognitive impairment in depression is well recognized but poorly under stood. A subset of depressed patients exhibit a syndrome of severe neu ropsychological deficits which may be partially reversible upon episod e resolution. This has been called depressive pseudodementia, the deme ntia syndrome of depression and depression induced cognitive impairmen t. The epidemiology, clinical features, natural history and prognosis of this condition support the notion of an underlying organic aetiolog y. The most plausible neurobiological candidate involved in the pathog enesis is hyperactivity of the hypothalamo-pituitary-adrenal (HPA) axi s. The homeostatic regulation of the HPA axis becomes increasingly vul nerable to disruption in geriatric depression and perhaps particularly in depressive dementia. Hypercortisolaemia has been correlated with c ognitive impairment in depression as well as in other related psychiat ric conditions. The mechanism of this abnormality may involve hippocam pal dysfunction. Further longitudinal studies are needed to clarify th e role of the HPA axis in the cognitive decline of depressive illness.