Late-life depression as a risk factor for dementia

Cognitive dysfunction accompanying depression has been considered to be separate from dementia and, thus, has been termed pseudodementia, with the presumption that it will disappear once the depressed mood remits. On the other hand, depression accompanied by dementia fulfills the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition definition of mood disorder due to its general condition. However, lately it has been documented that depression may precede dementia and, in particular, Alzheimer's disease. Dementia and depression display many common biological features, such as white matter changes in the brain, reduction of hippocampal volume, changes in the serotonergic and noradrenergic systems and abnormalities in the hypothalamic-pituitary-adrenal axis. These changes point to extensive system damage, beginning with dysthymia and depression episodes, which, over the years, lead to the development of dementia, possibly through hypersecretion of corticosteroids that may be toxic to the hippocampus.