I understand what you're experiencing with bouncing around. I am not familiar with Vascular dementia; however, for the past ten years, I have been tested and retested for Parkinson's Disease with two DaTscan(SPECT) that revealed my dopamine levels are good. DNA testing for other horrific diseases, in which I am grateful that I have not been diagnosed.
From what I understand, Parkinson's is a combination of diagnoses. I do have a B12 deficiency with a recent diagnosis of bowed vocal cords that can be associated with Parkisin's disease or onset of Parkinson's. I have many symptoms of Parkinson's without a concrete diagnosis.
Recently, my toes have begun to curl, which was painful, and I made an appointment with a new neurologist. While I am not seeking a disease, I am seeking a proactive approach for healing. I have never commented on the site before, as I have not been diagnosed with Parkinson's, but right now my diagnosis stands as unknown Ataxia.