The prevalence and incidence of dementia with Lewy bodies: a systematic review of population and clinical studies.

BACKGROUND: Dementia with Lewy bodies (DLB) is increasingly recognized as a common cause of dementia in older people. However, its true frequency remains unclear, with previous studies reporting a prevalence range from zero to 22.8% of all dementia cases. This review aimed to establish the population prevalence and incidence for DLB and to compare this to its prevalence in secondary care settings.

METHOD: A literature review of all relevant population and clinical studies was conducted using PubMed. Additional references from papers found during that process were added to this.

RESULTS: DLB accounted for 4.2% of all diagnosed dementias in the community. In secondary care this increased to 7.5%. The incidence of DLB was 3.8% of new dementia cases. There was a significant increase in DLB diagnoses when using the revised (2005) International Consensus Criteria (ICC) for DLB compared to the original (1996) criteria.

CONCLUSIONS: DLB currently accounts for around one in 25 dementia cases diagnosed in the community and one in 13 cases in secondary care. The significantly higher rates of DLB in secondary care may reflect enhanced diagnostic accuracy in specialist settings and/or the increased morbidity and carer burden of the DLB syndrome compared to other dementias. However, the true prevalence is likely to be much higher because DLB diagnoses are often missed, although there is evidence that new criteria aid case identification.