A new study has found that people who didn't have enough to eat as kids tend to have slower cognitive decline than people who always had enough food.

"These results were unexpected because other studies have shown that people who experience adversity as children are more likely to have problems such as heart disease, mental illness and even lower cognitive functioning than people whose childhoods are free of adversity," said Lisa L. Barnes, PhD, of Rush University Medical Center in Chicago, an author of the study.

More than 6,000 people with an average age of 75 participated in the study. 62 percent of the participants were African Americans. The participants were asked about their health as children, their family's socioeconomic condition, their home-environment etc. In addition, these participants took cognitive test for every three years for up to 16 years.

In the African American group, 5.8 percent of people who often didn't have enough to eat had slow cognitive decline than the rest of the group, researchers found. 8.4 percent of people in the group who reported that they were much thinner for their age (at 12 years old) were also more likely to have slow cognitive decline.

For Caucasians, however, researchers found no link between childhood adversity and mental decline.

Researchers haven't found the reason for the slow cognitive decline. One explanation is that calorie restriction might have slowed down aging in these people. Previous research has suggested that calorie restricting diet can increase lifespan by delaying age-related changes in the body.

Another explanation offered by the researchers is that these people might have been the most resilient of all the kids around them; those experiencing higher levels of adversity may have died before reaching old age.

People who had experienced adverse conditions during childhood continued to show slower cognitive decline even after researchers accounted for other factors like health and education levels.

The study is published in the journal Neurology.