What percentage of vascular dementia cases, characterized by disruption of blood flow, as by blood clots, are caused by chronic virus infection within the brain?

Here again is another variant being produced by viral irritation that damages locally, within the microvessels of the brain and larger vessels as well, as with atherosclerosis caused by viral presence, lodging and triggering an immune response that damages normal tissue. The consequences of the infection are first noticed as a stroke-like disruption of blood flow causing ischemic injury from lack of oxygenation. But this is simply one of multiple pathways that can manifest as differing symptomatic and pathologic tissue changes that are categorized, accordingly, as differing illnesses by current medical practice.