Many claims have been made for turmeric, including its therapeutic prowess to prevent or limit the ravages of Alzheimer’s. Research by the ethnobotanist James Duke suggests that extracts of turmeric include natural agents capable of thwarting the formation of beta-amyloid, a substance that over time hinders cognition and leads to Alzheimer’s.
In his book The End of Memory: A Natural History of Aging and Alzheimer’s, Jay Ingram notes that more than 50 studies link curcumin, turmeric’s active chemical, to lower rates of Alzheimer’s in India than in most other countries. “In the lab, curcumin both discourages amyloid beta from aggregating and begins the process of disassembling already-formed amyloid beta fibrils,” Ingram writes. “Stepping up to the more complex arena of cell culture, curcumin performs well and is versatile, reversing or slowing several different chemical processes that contribute to Alzheimer’s…. [M]ice engineered to be susceptible to Alzheimer’s were put on a relatively low curcumin diet and after six months had fewer plaques and smaller loads of plaque-building material.”
But in a starkly counterintuitive finding, using higher doses of curcumin provided no protection from Alzheimer’s at all. It is well-known, according to Ingram, that lowering the levels of plaque doesn’t always enhance cognition. On the other hand, rats injected with amyloid plaque that were later fed curcumin performed better on water-maze navigation tests. The curcumin evidently counteracted the damage wrought by the amyloid plaque.
This is an encouraging approach, but a good deal of testing awaits curcumin’s efficacy. Ingram’s book, which was published about eighteen months ago, cites a curcumin-related article in Ayu, a journal of Hindu traditional medicine. But the study had an obvious weakness: only three people participated. A clinical trial in Hong Kong, which included thirty-four people, did supply some useful data on such things as absence of side effects. But the placebo group in the study showed no palpable cognitive decline, drawing the conclusion that “it was impossible to conclude anything about the efficacy of curcumin.” Not exactly an encouraging result.
Ingram faults other studies, including one in Singapore with more than 1,000 participants, including Chinese, Indians and Malaysians in the age range of 60 to 93. He notes that while the scientists sought to control for numerous other influences, such as diet, exercising and smoking, the group might have included many undetected factors.
One particularly relevant study compared rates of Alzheimer’s in Ballabgarh, a rural district near Delhi in India, and the Monongahela Valley in western Pennsylvania. (Coincidentally, B. Smith, the former celebrity model, restaurateur and television personality who was diagnosed with early-onset Alzheimer’s in 2014, grew up in this area of Pennsylvania.) The difference in Alzheimer’s rates among the two regions is stark. According to Ingram, the rate in Ballabgarh among people older than 65 is just one percent. In the Monongahela Valley, the number appears to be about six times that rate. Tellingly, in the local language in Ballabgarh, there is no equivalent term for “dementia.”
One possible reason is that, much like in North America in the 1930s, elders in Ballabgarh are likely to live among extended families, and declining memory capabilities, it seems, are regarded as a common feature of getting older. One telling figure is that three-fourths of the people in the study were illiterate. Yet, a crucial feature, according to Ingram, is that far fewer people in Ballabgarh have the APOE4 gene, a marker for Alzheimer’s.
In a rather deflating conclusion, Ingram writes, “Obviously, when it comes to curcumin, the evidence that it actually plays a significant role is pretty scant.” But that’s no reason to stop—or in my case, to start—to consume turmeric on a regular basis. I happen to like Indian food quite a lot, especially the dishes with lentils or other legumes. And I plan to purchase a bottle of the pill version of turmeric soon after I finish writing this piece.