Scientists looking for a correlation between factors like childhood hunger and cognitive aging found a surprising result. Though earlier studies have shown that childhood adversity may be related to the incidence of health problems such as heart disease and mental illness in old age, new research shows that African Americans who went hungry during childhood experienced slower cognitive decline than those who did not, according to a recent study published by the American Academy of Neurology.
“The finding was unexpected,” said study author Lisa L. Barnes, Ph.D., of Rush University Medical Center in Chicago. “We hypothesized that early-life adversity would be related to faster decline.”
Researchers tracked more than 6,000 Chicago residents with an average age of 75, some for as long as 16 years. Each person was asked about his or her childhood health, family financial situation, and factors in their home learning environment, such as how often people played games with them or read to them. Then, participants were tested every three years for symptoms of cognitive changes.
Among African American participants, the 5.8 percent who reported they sometimes, always or often did not have enough food to eat as kids showed a slower rate of cognitive decline—by about one-third—than those who said they either rarely or never didn’t have enough to eat. The study also found that the 8.4 percent of African-Americans who remembered being much slimmer at age 12 than their counterparts had a slower rate of cognitive decline than those who said they were either heavier or the same size as other kids their age—again by about a third.
According to Barnes, the researchers don’t really know why, but there are two possibilities.
Some research on animals has found that calorie restriction may slow the onset of age-related diseases and lengthen lifespans. One human study found restricting calories lead to improved memory, but, the authors note, it was limited to a three-month period.
It’s also possible that it’s a question of selective survival. “Older adults with early adversity may represent the hardiest and most resilient; those with the most extreme adversity may have died before reaching old age,” the authors wrote.
In earlier studies of same population, researchers found obesity later in life is not related to a decline in cognitive function, Dr. Barnes said.
Zhenmei Zhang, an associate professor of sociology at Michigan State University who has studied early life influences and cognitive decline among older Chinese populations, found the results surprising as well.
“No studies that I know of have reported that childhood hunger is associated with slower cognitive decline, although there are reports that markers of childhood deprivation is not associated with cognitive decline in old age,” says Zhang, who was not involved in the study.
But Zhang also notes that the study of cognitive decline and aging is relatively new when compared to health problems like cancer and cardiovascular disease, which can cause death. It’s also a particularly important area of study as baby boomers grow older, as age is one of the strongest predictors of dementia.
The study’s authors did not find a relationship between childhood adversity and cognitive decline among Caucasians, though they’re not sure why.
“It could be that we did not have enough Caucasians who experienced extreme childhood adversity in our sample,” Barnes said. The majority of participants in the study—62 percent—were African American. The researchers purposely chose a geographic area with a high concentration of both Caucasians and African Americans with a diverse set of socio-economic statuses in order to create a better comparison.
However, Zhang notes, the small sample size of Caucasian participants who reported adversity is also a limitation of the study.
Researchers also found no correlation between the type of home learning environment individuals grew up in and cognitive decline, according to Barnes.
“People who reported not being told stories frequently or not playing games with someone frequently as a child, had lower scores on our cognitive tests at the beginning of the study – but they did not decline faster than those without adversity in the home,” she said.
In the study, the authors note that the results are for a particular population in the Midwest and “may not be generalizable to elders in other parts of the country.” However, Barnes said, the findings point to a need for further research into childhood experiences’ effects on disease later in life.
“The results of this study suggest that early-life factors are important and need to be considered in studies of cognitive decline and other diseases of aging,” Barnes said.
“Early childhood nutrition matters for old-age cognition but we know so little about how it works,” Zhang says. “There are also conflicting reports.”
The study is ongoing, and researchers will continue to examine the factors that affect aging in that population. The study was published December 11 in Neurology, the journal of the American Academy of Neurology.