This Explains a Whole Lot
It includes such things as being overweight, drinking ahem certain beverages, etc.
But there is another real beauty of a cause.
Being a vegetarian or vegan.
It seems that some of the things that a brain needs to function well is best obtained through meat, especially liver, fish and milk. That something is vitamin B-12 and animal products are the best source of it.
That explains the intelligence of those who think it's OK to kill an unborn child for mere convenience but wrong to kill an animal for food.
And the article was published in the Times of India, not exactly a meat-eater's paradise.
Bet that upsets a few people. I guess we were designed to be omnivores afterall.
The test was done mostly on older people but I would be most curious to see if there is any effect on younger people.