Can Curry Protect Against Alzheimer's?

Summarized by Robert W. Griffith, MD
January 22, 2007

Summary

Blood macrophages from Alzheimer patients have lost their ability to take up amyloid-beta protein, which is commonly found in the brain of such patients. Addition of curcuminoids (a curcumin complex derived from tumeric and curry) restores the ability of the macrophages to remove amyloid-beta.

Introduction

Elderly people in India have a low rate of Alzheimer's disease - about 1%, compared with roughly 4% for similarly aged persons in the USA. This fact inspired researchers in Singapore to study the possible association between eating curry and the frequency of Alzheimer's.¹ Curry is often spiced with turmeric, which contains curcumin, a potent anti-inflammatory and anti-oxidant, so it's a logical 'target' for such studies. The study employed over 1,000 non-demented Asians aged 60 to 93, measuring their Mini-Mental State Examination (MMSE) scores and categorizing them according to their curry intake as "never or rarely", "occasionally", and "often or very often". Those who ate curry "occasionally" and "often or very often" had significantly better MMSE scores than those who ate curry "never or rarely".

This sort of study provides the impetus for research to try to find evidence for a cause-and-effect mechanism that could account for the association found. Californian scientists have examined the effects of a curcumin complex on the ability of macrophages (scavenger blood cells) from Alzheimer patients to remove the specific amyloid protein that accumulates in the brains of people with Alzheimer's. The results of this study have been published in the Journal of Alzheimer's Disease, and we summarize them here.

What was done

Alzheimer patients have a build-up of plaques of the protein amyloid-beta in the brain, probably largely due to deficient removal of the material by macrophages and microglia (small nerve cells with a similar function). Curcumin complex and insulin-like growth factor increase the removal of amyloid-beta in animal models, providing the rationale for the present study in human macrophages.

Blood from six Alzheimer's patients and three normal volunteers was collected, and macrophage cultures established from each sample. Cells from the cultures were exposed to amyloid-beta combined with a fluorescent marker. Immunofluorescence microscopy using a confocal microscope was done to determine amyloid-beta uptake by the cells. The cultures were then treated with curcuminoids (Curcumin 3 Complex) overnight, and immunofluorescence microscopy repeated.

Results obtained

At baseline, the uptake of amyloid-beta by the macrophages from the normal subjects was significantly greater than that by macrophages from the Alzheimer's patients; moreover, uptake by the Alzheimer's macrophages was only seen as binding to the cell surface. The Alzheimer's cells did, however, phagocytose bacteria (E. coli and S. aureus) normally.

After overnight treatment with curcuminoids, there was significantly increased uptake of amyloid-beta in three of the six Alzheimer's patients' macrophages. Confocal microscopy showed that this was chiefly due to intracellular, rather than cellular-surface, uptake. The macrophages from the control volunteers had a high uptake of amyloid-beta originally, which was not influenced by curcuminoids.

Interestingly, the average MMSE score in the three patients whose macrophages didn't respond to curcuminoids averaged 20, while that of the three patients who did respond averaged 25. The non-responders averaged 78 years of age, compared to 62 years for the responders.

Comment

The important finding in this study was the significantly increased uptake of amyloid-beta by macrophages from half of the Alzheimer's patients (3 of 6) after curcumin. The responders were younger and had a higher MMSE score than the non-responders, suggesting that patients in a less advanced stage of Alzheimer's respond better.

At the end of their reports of the results, the scientists state that the patients involved were enrolled in a double-blind trial of oral Curcumin Complex or placebo administration. It's possible, therefore, that if they had been in the active treatment group of the study they might have been sensitized by the curcumin they had taken; we don't know this, though, as the code of the study (i.e. who got curcumin and who got placebo) has not yet been broken.

The results of this clinical study are awaited with great interest, obviously. If they are positive (i.e. curcuminoids are shown to improve or at least slow Alzheimer's), the laboratory experiment we've summarized above will have become an important contribution to our understanding of how Alzheimer's disease comes about. As an added benefit, the lab technique may prove to be a test to see which patients are likely to respond to curcuminoid therapy, and which will not.

Source

• Curcuminoids enhance amyloid-ß uptake by macrophages of Alzheimer's disease patients. L. Zhang , M. Fiala, J. Cashman,  et al., J Alzheimers Dis, 2006, vol. 10, pp. 1--7

Footnotes
1. Curry consumption and cognitive function in the elderly. T-P. Ng , P-C. Chiam, T. Lee,  et al., Amer J Epidemiol, 2006, vol. 164, pp. 898--906

Related Links
2001 Study of Curcumin in Mice Model of Alzheimer's
Curry Spice May Fight Alzheimer's Disease
Antioxidants Against Alzheimer's, Redux

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