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How long can an 80 year old live with dementia?: A Guide to Life Expectancy

According to a 2025 systematic review published in *The BMJ*, the average life expectancy for someone diagnosed with dementia at age 85 is approximately 2 to 4.5 years, depending on gender. If you are wondering how long can an 80 year old live with dementia, it is important to understand that many variables influence this prognosis, including the type of dementia and overall health.