My grandfather has alzheimers and it comes with dementia but the features of it are even stronger than your "average" dementia.
But what happens with a typical dementia is it starts fairly mildly and as time goes on, it gets worse as it begins to affect the person all the time.
The primary difference is that it's even worse with Alzheimers. Thing is, either in either case, it causes a lot of changes in their behavior. Especially with their sleep cycle. Then it adds a tremendous level of stress to the older person, which combined with all the other symptoms, can contribute to heart attacks and strokes that way.
Edited.. Like this -- person has dementia and needs to take medicines for high cholesterol and blood pressure. Dementia is stressing them out, they can't sleep well and are often forgetting to take their meds. Person catches a minor cold and combined with a coughing fit, stress, lack of sleep, not enough meds in their system, it triggers a heart attack and they are gone.
