Early-life adversity, including going hungry, may protect cognitive function as individuals age, new research shows.
Investigators found that people who experienced hunger as children and were thinner than average during childhood had a slower rate of cognitive decline over roughly 16 years.
"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," Lisa L. Barnes, PhD, from Rush University Medical Center in Chicago, Illinois, who worked on the study, said in a statement.
The study was published December 11 in Neurology.
Survival Effect?
The investigators analyzed the relationship between several measures of childhood adversity and the rate of cognitive decline in more than 6100 adults participating in the population-based Chicago Health and Aging Project. Their average age was 75 years and 62% were African American.
At baseline, participants provided information about their health as children, their family's financial situation, and their home learning environment, and they were given 4 standard tests of cognitive function. Their cognitive function was retested at roughly 3-year intervals for up to 16 years.
There was no relationship between any of the childhood adversity factors and cognitive decline among white participants.
However, the 5.8% of African American participants who said they went without enough food to eat sometimes, often or always were more likely to have a slower rate of cognitive decline, or decline that was reduced by about one third, than their counterparts who said they rarely or never went without enough food to eat.
The 8.4% of African American participants who reported that they were much thinner at age 12 than other kids their age also were more likely to have a slower rate of cognitive decline, also by one third, than those who said they were about the same size as or heavier than other kids their age.
These relationships were not mediated by years of education and persisted after adjustment for cardiovascular factors, the researchers note.
They admit that the biological basis underlying the apparent brain-protective effect of these childhood adversities in older African Americans is unknown.
However, there is evidence that caloric restriction delays the onset of various age-related physiologic changes and increases the lifespan, particularly in animal models. In addition, some studies in humans have suggested a role for caloric restriction in improved cardiovascular and glucoregulatory health and attenuation of oxidative stress.
"Mechanisms linking caloric restriction with improved health are not understood, but reduced inflammation and enhanced energy metabolism have been proposed, and would be consistent with a protective effect on cognitive decline," Dr. Barnes and colleagues write.
The investigators believe the findings could be due to a selective survival effect.
"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," they explain.
Practical Value Questionable
Reached for comment, neurologist Judy Willis, MD, from Santa Barbara, California, who was not involved in the study, told Medscape Medical News: "This is a well conducted study with refreshing honest self-reflection by the authors."
"The information is interesting," she said, "but the well stated statements of the authors regarding the population studied and how times have changed leaves the practical value lower than ideal."
"Also, the rough conclusions about possible critical periods where low caloric intake might have a protective effect on subsequent cognitive decline are, again as noted by the authors, very hypothetical and primarily investigated in animal research," Dr. Willis said.
The study was funded by grants from the National Institute on Aging; the National Heart, Lung, and Blood Institute; and the National Institute of Environmental Health Sciences. The authors and Dr. Willis have disclosed no relevant financial relationships.
Neurology. 2012;79:2321-2327
"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," Lisa L. Barnes, PhD, from Rush University Medical Center in Chicago, Illinois, who worked on the study, said in a statement.
The study was published December 11 in Neurology.
Survival Effect?
The investigators analyzed the relationship between several measures of childhood adversity and the rate of cognitive decline in more than 6100 adults participating in the population-based Chicago Health and Aging Project. Their average age was 75 years and 62% were African American.
At baseline, participants provided information about their health as children, their family's financial situation, and their home learning environment, and they were given 4 standard tests of cognitive function. Their cognitive function was retested at roughly 3-year intervals for up to 16 years.
There was no relationship between any of the childhood adversity factors and cognitive decline among white participants.
However, the 5.8% of African American participants who said they went without enough food to eat sometimes, often or always were more likely to have a slower rate of cognitive decline, or decline that was reduced by about one third, than their counterparts who said they rarely or never went without enough food to eat.
The 8.4% of African American participants who reported that they were much thinner at age 12 than other kids their age also were more likely to have a slower rate of cognitive decline, also by one third, than those who said they were about the same size as or heavier than other kids their age.
These relationships were not mediated by years of education and persisted after adjustment for cardiovascular factors, the researchers note.
They admit that the biological basis underlying the apparent brain-protective effect of these childhood adversities in older African Americans is unknown.
However, there is evidence that caloric restriction delays the onset of various age-related physiologic changes and increases the lifespan, particularly in animal models. In addition, some studies in humans have suggested a role for caloric restriction in improved cardiovascular and glucoregulatory health and attenuation of oxidative stress.
"Mechanisms linking caloric restriction with improved health are not understood, but reduced inflammation and enhanced energy metabolism have been proposed, and would be consistent with a protective effect on cognitive decline," Dr. Barnes and colleagues write.
The investigators believe the findings could be due to a selective survival effect.
"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," they explain.
Practical Value Questionable
Reached for comment, neurologist Judy Willis, MD, from Santa Barbara, California, who was not involved in the study, told Medscape Medical News: "This is a well conducted study with refreshing honest self-reflection by the authors."
"The information is interesting," she said, "but the well stated statements of the authors regarding the population studied and how times have changed leaves the practical value lower than ideal."
"Also, the rough conclusions about possible critical periods where low caloric intake might have a protective effect on subsequent cognitive decline are, again as noted by the authors, very hypothetical and primarily investigated in animal research," Dr. Willis said.
The study was funded by grants from the National Institute on Aging; the National Heart, Lung, and Blood Institute; and the National Institute of Environmental Health Sciences. The authors and Dr. Willis have disclosed no relevant financial relationships.
Neurology. 2012;79:2321-2327
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