In the early stage it is extremely difficult to make an accurate diagnosis because so many symptoms can overlap between different dementias, but also to other psychiatric illnesses. Many people with dementias also have comorbidities of depression or anxiety than can affect their cognitive performance. So, longitudinal history is the best, if it’s a sudden onset we can think of more of a vascular picture, mini-strokes can cause symptoms that look quite similar to Alzheimer’s dementia. With Lewy Body dementia, that’s on the spectrum of Parkinson’s disease, and patients often develop motor symptoms later on. Early on, they can have cognitive symptoms without any motor symptoms.
With Frontotemporal dementia, which can happen a bit earlier on, people can have changes in personality, but they might not have the short-term memory problems that you would see with other types of dementia. Also, within Alzheimer’s dementia there’s such a variable presentation, no two patients present identically.