Question

On average, the total brain weight of people in their 80s is about ___ less than that of middle-aged people. however, for those with dementia, it is about ___ percent.

Answer 1

The answer is 8% and 12%
Dementia happen because many of the brain cells became dead and unable to fulfill its usual function.
The dead cells create lesser compositon inside the brain which lead to lower-than average brain weight.