According to the Alzheimer's Society, the average life span for a patient with vascular dementia is around five years after symptoms begin manifesting. Oftentimes, the patient's death is caused by a stroke or heart attack.
The Alzheimer's Society states that vascular dementia is generally caused by a stroke or series of small strokes. This causes brain cells to become deprived of oxygen and die. Further, this process can occur in distinct areas of the brain while other areas are left unaffected. As a result, it is sometimes difficult to tell Alzheimer's and vascular dementia apart. However, one main difference between the two is that vascular dementia occurs in a "stepped" manner; symptoms may progress and stall depending on the frequency of strokes.