CABI Blog

Like many over 50’s I have aged parents: the health of mine is falling apart and finally they are facing up to moving from the only house they have ever owned after nearly 50 years. It’s a worry for me but at least their minds are intact. Unfortunately this is not the case for everyone.

A paper published early online (Changes in folate, vitamin B12, and homocysteine associated with incident dementia, Kim et al, J. Neurol. Neurosurg. Psychiatry 2008; doi 10.1136/jnnp.2007.131482) reports that folate deficiency is associated with a tripling of dementia risk amongst the elderly.

The researchers conducted a prospective community survey which followed the development of dementia in 518 people over a 2 year period from 2001 to 2003. All participants were over the age of 65, showed no signs of dementia at the start, and lived in one rural and one urban area in Kwangju, South Korea. Their blood levels were monitored at the start and at follow-up 2 years later (average was 2.4 years) for levels of folate, vitamin B12, and the protein homocysteine. (High levels of homocysteine have been associated with cardiovascular disease: earlier cross-sectional studies have found links between low folate/high homocysteine with dementia or cognitive impairment but prospective findings were inconsistent). Baseline assessment also included other variables: sociodemographic data, disability, depression, smoking, alcohol consumption and physical activity.

At the start nearly one in five people (19.7%) had high levels of homocysteine, while 17.4% had low vitamin B12 levels and 3.5% were folate deficient. The higher the levels of folate to begin with, the higher were vitamin B12 levels, and the lower those of homocysteine.By the end of the study, 45 people had developed dementia. Of these, 34 had Alzheimer’s disease, seven had vascular dementia, and four had “other” types of dementia.

The results showed that people who were folate deficient to begin with, were 3.4 times more likely to develop dementia. Over the 2.4 years, the onset of dementia was significantly more likely in those whose folate levels fell whilst their homocysteine levels rose (it’s the change rather than the baseline concentration). All measurements were adjusted for weight change occurring in the same period. Changes seen in folate and vitamin B12 levels (declines) were entirely responsible for the link between high homocysteine and dementia. This led the authors to suggest that the rise in homocysteine in dementia might have a nutritional basis.

Dementia was also more likely in those who were older, relatively poorly educated, inactive, showing poor cognition and had deposits of the protein ApoE4. (ApoE is essential for the normal catabolism of triglyceride-rich lipoproteins: the ApoE4 genotype is a risk factor for Alzheimers disease).

The authors suggest that changes in micronutrients could be linked with the other typical signs that precede dementia, including weight loss and low blood pressure. With smaller appetites and tight budgets, dietary changes in the elderly could be responsible for both weight loss and folate deficiency.

One thing that occurred to me is that the demented tend to have poor disorganised diets: did the authors know what diets these people were truly eating? They did point out that vitamin supplementation data was only assessed at followup and no details of the vitamin preparations used was collected. Most supplements in Korea contain vitamin B12, not folate, so the fact that overall folate levels declined in the study sample whilst vitamin B12 levels rose, they felt, could reflect this.

Its obviously a complex story. Whether nutritional status is a cause or an effect of dementia, elderly people need to be eating a proper diet.

The press alert from the BMJ did not actually mention the country in which this study originated: I was delighted to discover it was Korea. Why? Because it truly is an example of “Global solutions for local problems”, the concept behind our public health database Global Health.

Which leads me back to Global Health. The problem of dementia and possible nutrient prevention has been examined before, although not with such compelling results. Under References, I have listed examples in this database which basically cover the role of fish in the diet (especially unprocessed or fatty fish, PUFAs in fish).

And the moral: Feed your parents well, little and often, heavy on the spinach, oily fish & pumpkin seeds and the odd glass of red wine….

References:

1. Cognitive performance among the elderly and dietary fish intake: the Hordaland Health Study, Nurk et al. American Journal of Clinical Nutrition (2007) 86: 5, 1470-1478.
2. Low plasma N-3 fatty acids and dementia in older persons: the InCHIANTI study. Cherubini et al. The Journals of Gerontology Series A: Biological Sciences and Medical Sciences (2007) 62:1120-1126.
3. Intake of flavonoids and risk of dementia. Commenges, D. et al European Journal of Epidemiology (2000) 16: 4, 357-36.
4. Advances on the effects of grassleaf sweetflag (Acorus gramineus) on central nerve system. Tian Rong  et al. Chinese Journal of Information on Traditional Chinese Medicine (2006)13: 3, 101-103.
5. Curry consumption and cognitive function in the elderly. Ng TzePin et al American Journal of Epidemiology (2006) 164: 9, 898-906.
6. PUFAs and risk of cognitive decline or dementia: epidemiological data. Barberger–Gateau, P. OCL – Oléagineux, Corps Gras, Lipides (2007) 14: 3/4, 198-201.
7. Poor nutrient intakes during 1-year follow-up with community-dwelling older adults with early-stage Alzheimer dementia compared to cognitively intact matched controls. Shatenstein, B. and Reid, I. Journal of the American Dietetic Association (2007) 107: 12, 2091-2099.

A useful searchstring for Global Health, if you have a subscription, is: …dementia!

You could of course use dementia and diet or dementia and elderly.