I came across an interesting article online about the occurrence risk of dementia. So, I would like to summarize and share some of the interesting points here. The article said the research showed there is strong correlation between head size and the appearance risk rate of dementia. According to the tracing research of elderly nuns for 30 years, those who has small head size and didn't have much opportunities to study showed 4 times as high risk of dementia as the others. The reason why the research team focused on nuns was because they belongs to the same religious order and their lifestyle are almost the same such as not smoking and not drinking. The analysis result indicated the participants with their small head size and small opportunities of study had the possibility about 4 times as high as those who have large head size and high level of education, which is diagnosed as dementia. Those who fall under either one didn't show an increase of the risk at all. The research team explained that the total volume of brain cells is also small as a head size is small. Those kind of brains can have low performance to handle a damage due to aging and a change due to dementia. On the other hand, large head size means brain's one as well and plenty of brain cells and that causes to increase cognitive reserve. So, it can be easy to maintain the performance even though a part of brain is damaged by aging. They pointed out that an environment and education have very important meaning because people can't win with their own head size. They also said that building education through your lifetime is very crutial. Honestly, I'm not sure how much and how long we should keep studying, but I guess trying to maintain an interest in anything and know about it is important.