People who haven’t graduated high school are at a higher risk of developing Alzheimer’s disease and dementia, according to a new study.

Better-educated individuals have a better chance of avoiding the mental diseases, according to the study conducted in Finland and published in the medical journal, Neurology, regardless of income, occupation, physical activity and whether they smoke or not.

Researchers studied 1,388 participants throughout their middle-age and late-life for approximately 21 years. Volunteers were divided into three levels, including five or less years of education, six to eight years of eduction, and nine or more years of education, representing the educational equivalent of elementary, middle and high school levels in Finland.

People with a lower education level, or a medium education level, had a 40 percent lower risk of developing dementia while those with a higher education had an 80 percent lower risk.

“Generally speaking, people with low education levels seem to lead unhealthier lifestyles, which could suggest the two work concurrently to contribute to dementia or Alzheimer’s disease, but our results showed a person’s education predicted dementia on its own,” said study author Dr. Tiia Ngandu, PhD, of the Karolinska Institute in Stockholm, Sweden, and University of Kuopio, Finland.

“It may be that highly educated people have a greater cognitive reserve, which is the brain’s ability to maintain function in spite of damage, thus making it easier to postpone the negative effects of dementia," she added. "Additionally, unhealthy lifestyles may independently contribute to the depletion of this reserve.”