New research suggests that speaking more than one language may delay different kinds of dementia , that is the loss of mental ability. In fact, researchers say, speaking two languages appears to be more important than the level of education in defending against dementias. A study in India examined the effect of knowing more than one language in delaying the first signs of several dementias. Researchers studied nearly 650 people whose average age was 66. 240 of those studied suffered from Alzheimer's, the most common form of mental decline . 391 of the _ spoke two or more languages. Researchers found the dementias began about four-and-a-half years later in those who spoke two languages compared to those who spoke only one language. The level of education had no effect on the age at the first sign of dementia. Thomas Bak, from the Center of Cognitive Aging at the University of Edinburgh in Scotland, who helped to organize the study, suggests that individuals who speak more than one language train their brains by moving back and forth between different words and expressions. He also believes this effort improves what scientists called executive  functioning, which often weakens in people with dementias. He states that researchers found there was no extra gain in speaking more than two languages. Mr Bak says it does not appear important whether you learn another language at a young age or later in life. It's not something that "you missed the boat when you do not do it as a baby." It is something that is still quite useful and powerful when you do it as an adult. This passage may probably be seen in  _  .
a research plan a health magazine a book review a business magazine