How do I know what kind of dementia my mom has? Med records show she had it before her stroke 3 years ago, but it's way worse.

I am not a doctor but I have looked into the various types a bit. cwillie is correct she probably had many mini strokes or TIAs that she wouldn't have noticed that affected blood supply to the brain. If it were Lewy Bodies Dementia there would be a blood test for that I believe and there is more pain associated with this as it progresses. There is a frontotemporal dementia which affects the part of the brain for the short term memory, this can make the sufferer more abusive and hard to handle behavior wise. My dad has this (Vascular Frontotemporal) and his appetite is huge and he has a typical dementia shuffle where they don't pick up their feet when walking, more like shuffle across the floor. The frontotemporal lobe damage affects balance and results in the shuffle. So I guess you can tell a bit yourself from these traits. Vascular Dementia is damage to the vessels from lack of blood supply no matter where there is a high incidence in smokers and alcoholics, although my father was neither. Alzheimers on the other hand is a shrinking brain and can be detected on a CT scan if the brain is getting smaller (conclusively only on autopsy). If you are wondering about a genetic risk, the fact that your mother has the diabetes and probably had poor circulation to the brain etc it may be less of a genetic connection than the shrinking brain type. My father's long term memory from his childhood is intact and is all he talks about, he forgets the names of people and places but the story is very detailed.

How do you know it isn't at least partially vascular dementia? VaD is a consequence of problems with blood supply to the brain - it is very possible the before her stroke she had a history of TIAs and diabetes is considered one of the risk factors. Changes in the brain can show up on advanced MRIs or PET scans, has she had either of those?