Researchers at Cambridge University say that the time spent in education may reduce people's risk of dementia later in life.
The researchers compared the mental abilities of elderly people, and found that those born after the school leaving age was raised in the country fared better.
Based on that observation, the researchers came to the conclusion that further changes to the school leaving age could improve mental abilities and curb dementia rates more.
They, however, conceded that more information on how education affected dementia was needed.
For their research, the study group compared a group of over 9,000 people aged over 65 tested in 1991 with over 5,000 over-65s tested in 2002.
The researchers gave the subjects a standard test used to detect early signs of dementia, which involved naming as many animals as possible within a minute.
The team observed a small but potentially significant increase in the number of words a minute people used in the later group.
The school leaving age was set at 15 in 1947, rising to 16 in 1972.
The government announced two years ago that, by 2015, teenagers would have to stay in education or training until they were 18.
"The increase in educational levels that we observed is consistent with changes in the mandatory school leaving age in England," the BBC quoted the researchers as writing in the journal Aging, Neuropsychology and Cognition.
Lead researcher Dr. David Llewellyn said: "Dementia happens when people decline cognitively to the point where it interferes with their ability to do basic things like cook. It tends to happen later in life, but the changes that lead to it tend to start much earlier.
He added: "These findings are important because they affect our projection of what's likely to happen in the future. It's not going to prevent what is essentially an epidemic of dementia, but it may mean it might not be quite as bad as we have predicted."
The researcher believes that changes to the school leaving age after the period covered in the study should have also led to improvements in cognitive abilities, and thus mitigated dementia rates.
He said: "When talking about what we should do in terms of education and changes to the school leaving age, this kind of study should feed into it."
However, Neil Hunt, chief executive of the Alzheimer's Society, said: "Whilst we have a lot of really good evidence on healthy lifestyles and the fact that they can decrease risk of dementia, there isn't enough evidence on education and dementia to draw any conclusions. We know conditions such as diabetes and obesity are on the rise and that they increase people's risk of dementia, unfortunately this may have the opposite effect."