This has always puzzled me? When Mum was diagnosed with Dementia caused by Alzheimers in 2013, her brain CT scan showed normal age related changes and no obvious signs of vascular damage. I imagine then in the absence of physical causes, it was based on her memory tests (19/30) and other symptoms and behaviours noted by us. Mum is on 5mg of Donepezil. Last year Dad was referred to the memory team. In comparison his brain CT showed significant atrophy in frontal lobes, ischemic small vessel damage and and another area of damage which they attributed to his days of being an amateur boxer. However they said the tests showed his memory was not bad for his age, but did have cognitive impairment especially when it came to visuo spatial awareness, and he did not have dementia. ( hmmmm?) It puzzles me how Dads brain can show much more damage than Mums, but Mum is the one with Alzheimers??