People with dementia survive an average of four and a half years following their diagnosis, new British research shows.
However, age, sex and any existing disability can alter life expectancy, according to the report in the British Medical Journal.
Common socioeconomic influences, such as marital status, social class and living in a community or residential home, did not appear to have an influence on longevity, the study found.
Researchers analysed data on more than 13,000 people aged 65 and older who took part in a population-based study in England and Wales and were regularly assessed for dementia between 1991 and 2005.
During the 14-year study period, 438 of the participants developed dementia and 356 (81 percent) of those people died.
Dementia is known to be associated with increased risk of death, but considerable uncertainty exists about what influences survival. Worldwide, the number of people with dementia is estimated to reach 81 million by 2040.
The study found a nearly seven-year difference in survival between the youngest and oldest dementia patients - 10.7 years for those aged 65 to 69 and 3.8 years for those aged 90 and older.
Men have lower survival rate
The average survival time after dementia diagnosis was 4.6 years for women and 4.1 years for men.
People who were the most disabled at the time of diagnosis lived about three years less than those who were the least disabled.
People with more education had a slightly shorter length of survival than those with less education, but researchers said the difference was not statistically significant.
Understanding factors that affect survival time after a dementia diagnosis may help health-care providers, patients, caregivers and policymakers, the study authors said. - (HealthDay News)
Description of dementia
Causes of dementia