Background:
The authors reviewed studies published between 1992 and 2005 that reported on the prevalence and phenomenology of delusions in Alzheimer's disease (AD), as well as any relationship with cognitive decline.
Methods:
The terms ‘delusions, cognitive and Alzheimer's disease/dementia’ were used to search the PubMed and PsychINFO databases. Empirical investigations and reviews were included in our report but were dependent upon quantitative data on the above factors being available.
Results:
Data from a meta-analysis show that the overall prevalence for delusions in AD is 36%. There is, however, a broad range of reported prevalence rates across studies, from 9% to 70%. Variations in prevalence rates are because of methodological differences, such as inconsistent consideration of neuroleptic use, participants being included at various stages of AD and failure to consider other neuropsychiatric symptoms. One study did address factors that lead to inconsistent findings and subsequently reported that 34% of a sample of patients with AD were found to experience delusions and that these patients were at a higher risk of functional and cognitive decline. The phenomenology of AD delusions has not been adequately addressed; neither has whether AD delusions relate to specific cognitive deficits.
Conclusions:
Delusions in AD are common and are related to greater rates of cognitive decline. Future studies that explore the relationship between AD, delusions and cognitive decline need to control for methodological issues and need to examine the phenomenology of delusions and their relationship with specific cognitive deficits.
