It depends. Unfortunately, there is currently no cure for Lewy body dementia (LBD). The prognosis of someone with the condition depends on multiple factors, such as age of onset, the severity of their symptoms, and their other medical conditions.
In general, the average life expectancy for people with LBD after the onset of symptoms is 5 to 8 years. However, individuals with LBD have lived anywhere between 2 and 20 years depending on the factors above.
In fact, LBD doesn’t typically progress as predictably as Alzheimer’s does. Rather, because its symptoms can fluctuate, progression may vary significantly from one person to another.