Rapid cognitive decline in Alzheimer's disease: a literature review

Background: The rate of cognitive decline in Alzheimer's disease (AD) varies considerably between individuals. Predicting rapid cognitive decline might help clinicians provide prognostic information, select subjects for trial intervention and/or reduce costs. Methods: PubMed and PsycINFO were searched for all the English written studies published until the end of 2010 on rapid cognitive decline in AD and factors associated with it. Results: More than 300 individual articles were retrieved. We selected 82 relevant studies. The main findings of these papers are that younger, more educated and more impaired patients are more likely to show rapid cognitive decline. ApoE alleles seem not to modify the velocity of clinical progression of dementia, or at most could have a very small effect. No inference can be made for all the other variables analysed. Conclusions: There are many studies on rapid cognitive decline. Results are heterogeneous and often contradictory. No reliable conclusions about factors that may be associated with rapid cognitive decline can yet be drawn.