The average life expectancy of people diagnosed with dementia ranges from 9 years at age 60 to 4.5 years at age 85 for women and from 6.5 to just over 2 years in men, respectively, a study shows. systematic review of the latest evidence in The BMJ Today.
The results also suggest that a third of people with dementia are admitted to a nursing home within three years of diagnosis.
Nearly 10 million people worldwide are diagnosed with dementia each year, but survival estimates vary widely, and few studies have assessed prognosis (the likely course of the condition) in terms of time to nursing home admission.
To better understand this, researchers in the Netherlands have determined the prognosis for people diagnosed with dementia, both for remaining life expectancy and for the time until admission to a nursing home.
Their findings are based on 261 studies published between 1984 and 2024 (235 on survival and 79 on nursing home admission) involving more than 5 million people with dementia (average age 79, 63% women).
The studies were mainly from Europe and North America, with a mean follow-up duration of 7 years.
After assessing study quality, researchers found that average survival from diagnosis appeared to be highly dependent on age, ranging from 8.9 years at the average age of 60 for women to 2.2 years at the average age of 85 years for men.
Overall, dementia reduced life expectancy by about two years for people diagnosed at age 85, by 3-4 years with a diagnosis at age 80, and up to 13 years with a diagnosis at age 65.
Average survival was up to 1.4 years longer among the Asian population and 1.4 years longer among people with Alzheimer’s disease compared to other forms of dementia.
The average time to nursing home admission was just over three years, with 13% of people admitted in the first year after diagnosis, rising to a third (35%) after three years and more than half (57% ) after five years. However, the authors note that these estimates are less reliable and should be interpreted with caution.
These are observational findings and the authors acknowledge that differences in study methods and inconsistent reporting of measures such as socioeconomic status, race, disease severity, and pre-existing conditions may have affected their estimates.
However, they point out that the rigorous search and data extraction allowed for analyzes of the largest number of studies to date over an extended period of time, “offering potential for individualized prognostic information and care planning.”
They conclude: “Future studies of individualized prognosis should ideally include patients at the time of diagnosis, taking into account personal factors, social factors, disease stage and comorbidities, while assessing relevant functional outcome measures beyond survival.”
In a linked editorial, researchers from Norway say that while the understanding of surviving with dementia has improved substantially, the complexity of predicting the timeline for nursing home admission remains.
“To improve future healthcare services and optimize the quality of life for people with dementia and their families, it is critical that we continue to strive for more precise, context-sensitive insights,” they conclude.