Hello my mom is 57 with frontal temporal dementia and she has started to show late stage signs and I just wanted to know how long she has left because she no longer talks she just mumbles or she just repeats the same word over again. Some of her other symptoms are she wonders around and doesn't know any concepts of time, she also like to spend most of her time in bed.
Have you considered having her evaluated by hospice care?
No one can predict with certainty, but professionals with lots of experience may have some ballpark figures for you.
I am so sorry that your mother is facing this so young.
From what I've read, folks with FTD have extremely variable life spans. While the average life expectancy after diagnosis is about 7 years, some patients die after 18 months, while others survive for 20 years with this form of dementia.
Let us know what the doctor tells you, and what your plans are.