Those searching for a "smart pill," might find the necessary ingredients in spicy Mexican food, according to recent research showing that certain Mexican food spices boost memory.
In a study published in the Journal of Pharmaceutical Biology, researchers spiked the drinking water of rats with an extract of the savory spice cumin, which is commonly used in Mexican and Indian food. Then they tested the rat's rate of learning and memory retention. The researchers trained rats to jump onto a pole at the sound of a buzzer to avoid a punishing electric shock delivered through the metal floor of their cage. Rats drinking pure water learned to avoid the shock perfectly after 11 days of lessons. Rats imbibing the cumin-tainted water learned faster. Those receiving the highest dose of cumin extract learned to escape the shock after only eight days of lessons, and the length of time it took rats to learn this task was proportional to the concentration of cumin extract they had been drinking.
Once the rats learned the task perfectly, the researchers treated them with a drug causing amnesia -- scopolamine -- which works by inhibiting function of the neurotransmitter acetylcholine in the brain. A decrease in this neurotransmitter is also associated with memory loss in Alzheimer's disease. The drug severely impaired the memory of trained rats, such that only about 40 percent remembered to jump to the pole when the buzzer sounded, but the amnesia drug had only a slight effect on rats that were drinking the highest concentration of cumin-laced water. Unlike the control rats, which took another five days of re-training to re-learn that they needed to jump onto the pole when the buzzer sounded, rats drinking the strongest dose of cumin extract re-learned to escape in only two days. The protection from memory loss and the length of time it took to re-learn after amnesia were directly proportional to the concentration of cumin extract the rats were fed.
A study by a different group of researchers published earlier this year in the Journal of the Science of Food and Agriculture found that the pungent herb cilantro, also known as the leaves of coriander, also boosts memory, and the findings may point to a new treatment for Alzheimer's disease. Both cumin and cilantro are commonly used as spices in Mexican and Indian food. In this study, researchers added ground cilantro leaves to the rats' food in 5 percent, 10 percent, or 15 percent portions by weight. Both young and old rats performed better in learning to run a maze compared with rats that were not fed cilantro, and the benefits were directly proportional to the amount of cilantro in their diet.
Additional tests showed that when the drugs scopolamine or diazepam were given to induce amnesia, rats suffered less memory loss in direct proportion to the amount of cilantro in their diet. In fact, almost no memory loss was detected in rats fed the highest concentration of cilantro after treatment with the amnesia-inducing drugs.
In this case, the researchers were able to provide direct evidence explaining how the spice could boost memory. They measured how potent the enzyme in the rat's brain was in breaking down the neurotransmitter acetylcholine. In both young and old rats, the activity of the cholinesterase enzyme was suppressed by cilantro. Less neurotransmitter breakdown translates into more acetylcholine in the brain -- interesting, considering this neurotransmitter deficiency is associated with Alzheimer's disease.
Not even the most fanatic Mexican food lover consumes 5-15 percent of their diet in cilantro leaves, and attempting this would likely induce a bad case of "tourista," but if the active compounds in cilantro and cumin can be identified, this could provide useful new drugs for treating dementia.
Koppula, S., Choi, D.K. (2011) Cuminum cyminum extract attenuates scopolamine-induced memory loss and stress-induced urinary biochemical changes in rats: A noninvasive biochemical approach. Pharmaceutical Biology, 49; 702-708.
Mani, V., Parle, M., Ramasamy, K., Majeed, A.B.A. (2011) Reversal of memory deficits by Coriandrum sativum leaves in mice. J. Sci. Food Agric. 91; 186-192.