Dementia in the National Cause of Death Registry in Norway 1969-2010

Background: The prevalence of dementia is expected to increase markedly during the coming decades. Epidemiological studies involving the National Cause of Death Registry (NCDR) may be useful for exploring the aetiology of dementia. We therefore wanted to study developments in the reporting of dementia in the NCDR over the last four decades. Methods: We calculated the ageand gender specific proportion of deaths with dementia reported in the NCDR (dementia deaths) in the period 1969-2010, and the proportion of vascular dementia and Alzheimer’s disease deaths in 1986-2010. Separate analyses were done for deaths occurring in nursing homes in 1996-2010. The proportion of dementia deaths where dementia was coded as underlying cause of death was also calculated. Results: The proportion of dementia deaths increased more than threefold in the period 1969-2010 among women (from 4% to 15%), and more than doubled among men (from 3% to 7%). In nursing homes the proportion increased from 17% to 26% for women and from 13% to 18% for men. The proportion of dementia deaths with Alzheimer’s disease reported in the NCDR increased from practically zero in 1986 to a maximum of 28% in 2005. The proportion of dementia deaths with dementia as underlying cause of death increased from a minimum of 6% in 1972 to a maximum of 51% in 2009. Conclusion: Although the reporting of dementia in the NCDR increased markedly from 1969 to 2010, dementia is still under-reported for old people and for deaths occurring in nursing homes when compared to prevalence estimates.