Although Alzheimer's disease and dementia are often used as synonyms there are a number of different types of dementia. A French study followed the progress of 970 people attending a memory clinic between 1995 and 2001, monitoring them for an average of 4.7 years. 663 had Alzheimer's, 166 had Alzheimer's and cerebrovascular disease and 141 had vascular dementia. The participants with Alzheimer's and cerebrovascular disease tended to be older. Those patients with vascular dementia had the best cognitive function at the start of the study. Decline in cognitive function was greatest for patients with Alzheimer's alone, then for people with Alzheimer's and cerebrovascular disease followed by people with vascular dementia. The shorter the time between the onset of symptoms and the first visit to the memory clinic the longer the patients survived highlighting the importance of early diagnosis for this group.
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