What is a decrease in brain function that includes personality changes and memory loss?

The correct answer is: dementia.

Dementia is a general term for a decline in mental ability severe enough to interfere with everyday activities. Alzheimer's disease is the most common type of dementia. There are many possible causes of dementia, including:

* Alzheimer's disease

* Vascular dementia (caused by stroke or poor blood flow to the brain)

* Lewy body dementia (caused by abnormal protein deposits in the brain)

* Frontotemporal dementia (caused by damage to the frontal and temporal lobes of the brain)