Which factors influence cognitive decline in older adults suffering from dementing disorders?

Although extensive research has been done on dementing disorders in recent decades, their natural course and prognosis are not yet well understood. The aim of our study was to assess cognitive decline in a representative sample of demented elderly and to analyse the predictive value of a broad spectrum of sociodemographic, neurological and clinical variables.

A random sample of elderly patients in primary care (n = 407) was drawn from a total of 3721 patients. The sample has been stratified according to the degree of cognitive impairment as assessed by their GPs. The patients were examined by means of a standardized research interview, including comprehensive cognitive testing (Hierarchic Dementia Scale) and the assessment of neurologic and physical impairments as well as of mental state (CAMDEX criteria). After a mean interval of 28 months, a follow-up study was conducted using essentially the same instruments.

At baseline, 117 of the 407 patients were identified as suffering from mild, moderate, or severe dementia. The two-year follow-up of those patients revealed high mortality rates (53/117). The surviving patients showed significant cognitive decline, although the rate varied considerably between individuals. The rate of progression was strongly related to the initial degree of severity, but also to the use of psychotropic medication, which was associated with a more rapid deterioration.

There are some prognostic indicators that can help to establish the prognosis for dementia patients. The best indicator for both--the rate of cognitive decline and the probability of survival--is the severity of dementia.