Undifferentiated dementia, Alzheimer's disease and vascular dementia: age- and gender-related incidence in Liverpool - The MRC-ALPHA Study

Background Does incidence of dementia follow the age pattern of prevalence? Is gender a risk factor? Do patterns of incidence differ between dementias? Aims To assess age-specific incidence rates of undifferentiated dementias, Alzheimer's disease and vascular dementia. Method 5222 individuals aged greater than or equal to 65 years. were interviewed using the Geriatric Mental State/History and Aetiology Schedule. The AGECAT package was used to identify cases at three interviewing waves at two-year intervals. Diagnoses were made using ICD-IO Research Criteria and validated against neurological and psychological examination, with imaging and neuropathology on unselected subsamples. Results incidence rates of the dementias increase with age. Age patterns are similar between Alzheimer's disease and vascular dementia. Gender appears influential in Alzheimer's disease. In England and Wales, 39 437 new cases of Alzheimer's disease (4.9/1000 person-years at risk); 20 513 of vascular dementia (2.6/1000 person-years) and 155 169 of undifferentiated dementia (19/1000 person-years) can be expected each year. Conclusions Incidence rates for Alzheimer's disease and vascular dementia appear to behave differently. with an increased risk of Alzheimer's disease for women compared to vascular dementia. Declaration of interest Funding was received from the Medical Research Council (UK), Lilly Industries and the Human Ageing Trust.