There are different reasons why dementia may progress faster than usual. One of the reasons is having different autoimmune diseases. Another possible reason has a head injury. This can cause the brain cells to die more rapidly, which can cause memory loss and further issues that are usually related to dementia. Some may also have a higher chance of acquiring dementia when there is limited blood flow to the brain.
The brain would need oxygen coming from the blood. Otherwise, it will not function. When there is no blood flow, the brain cells will start to die, and this can cause rapid dementia. There is no cure for dementia, but there are different things that people can do to reduce the rapidness of the disease, possibly.