And these are the features that break the backs of caregivers and often lead to institutional placement. The risk of dementia increases with age. Though it becomes more prevalent with age, people can develop dementing illnesses as early as the 30's or 40's. Being a woman seems to be a risk factor for Alzheimer's disease. It's more correct to say that people die from the complications of dementia.
People die from infections, fractures, and complications of immobility.
It's sometimes not an easy distinction to make but forgetfulness that normally accompanies aging is usually a problem of retrieval. The memory is in there somewhere, but you have trouble retrieving it. For example, it may take a moment to remember somebody's name, or where something was placed, but eventually you do remember the name or place. And that in fact is something people in their 40's or 50's begin to report. In contrast with Alzheimer's dementia, it's more fundamentally a problem of encoding.