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Vascular & Mixed Dementia

Prevalence

Vascular dementia, as its name suggests, is caused by poor blood flow, produced by a single, localized stroke, or series of strokes.

It is the second most common dementia, accounting for perhaps 17% of dementias. It also co-occurs with Alzheimer's in 25-45% of cases. Although there are other types of dementia that also co-occur with Alzheimer's, mixed dementia generally refers to the co-occurrence of Alzheimer's and vascular dementia.

Risk factors

In general, unsurprisingly, vascular dementia has the same risk factors as cerebrovascular disease.

A study1 of 173 people from the Scottish Mental Survey of 1932 who have developed dementia has found that, compared to matched controls, those with vascular dementia were 40% more likely to have low IQ scores when they were children than the people who did not develop dementia. Because this was not true for those with Alzheimer's disease, it suggests that low childhood IQ may act as a risk factor for vascular dementia through vascular risks rather than the "cognitive reserve" theory.

Prevention

The exciting thing about vascular dementia is that it is far more preventable than other forms of dementia. As with risk, as a general rule, the same things that help you protect you from heart attacks and stroke will help protect you from vascular dementia. This means diet, and it means exercise.

A four-year study2 involving 749 older adults has found that the top one-third of participants who exerted the most energy in moderate activities such as walking were significantly less likely to develop vascular dementia than those people in the bottom one-third of the group.

Treatment

Apart from normal medical treatment for cerebrovascular problems, there are a couple of interesting Chinese studies that have looked specifically at vascular dementia.

The herb gastrodine has been used in China for centuries to treat disorders such as dizziness, headache and even ischemic stroke. A 12-week, randomized, double-blind trial3 involving 120 stroke patients who were diagnosed with mild to moderate vascular dementia has found that  gastrodine and Duxil® (a drug used to treat stroke patients in China) produced similar overall levels of cognitive improvement -- although more patients showed 'much improvement' with gastrodine (23% vs 14%).

A Chinese pilot study4 involving 25 patients with mild to moderate vascular dementia found that ginseng compound significantly improved their average memory function after 12 weeks, but more research (larger samples, placebo-controls) is needed before this finding can be confirmed. Five years on I have still not seen such a study.

References
  1. McGurn, B., Deary, I.J. & Starr, J.M. 2008. Childhood cognitive ability and risk of late-onset Alzheimer and vascular dementia. Neurology, first published on June 25, 2008 as doi: doi:10.1212/01.wnl.0000319692.20283.10
  2. Ravaglia, G. et al. 2007. Physical activity and dementia risk in the elderly. Findings from a prospective Italian study. Neurology, published online ahead of print December 19.
  3. Tian, J.Z. et al. 2003. A double-blind, randomized controlled clinical trial of compound of Gastrodine in treatment of mild and moderate vascular dementia in Beijing, China. Presented at the American Heart Association's Second Asia Pacific Scientific Forum in Honolulu on June 10.
  4. Tian, J.Z. et al. 2003. Presented at the American Stroke Association's 28th International Stroke Conference on February 14 in Phoenix. Press release
Dementia