A number of studies have shown an association of socioeconomic status with a longer life span, and a recent study expands upon this research to examine the impact of childhood and adult socioeconomic status on physical and cognitive functioning later in life. A representative sample of 2,229 adults ages 60 to 64 was given nine physical and cognitive performance tests. Examples of the physical tests include hand grip strength, the time it took to rise from a chair, and a standing balance test. Examples of the cognitive tasks include tests of verbal memory and reaction times.
The individuals in this study had been part of a larger study on health and development since childhood. This permitted the researchers to also determine how childhood performance on cognitive tests involving reading comprehension, vocabulary, and nonverbal reasoning at age eight might be associated with adult outcomes at ages 60 to 64. Since adult height has been associated with childhood nutrition and disease as well as later outcomes in adult physical health, the researchers also took into account the differences in participants’ adult height to look for a potential impact of childhood nutrition and disease on the outcomes measured here. Since previous studies had shown large gender differences in some of the tests conducted here, male and female results were calculated separately.
Socioeconomic position was assessed by looking at occupational class. The participants’ childhood socioeconomic class was based on a coding of the father’s occupation when the participant was four years of age. Adult socioeconomic class was based on a coding of occupation of the head of the participant’s household when the participant was 53 years old. This adult age was used because by the time of this study, half of the men and three-quarters of the women had retired from their main job.
Looking at only childhood socioeconomic position, this study showed performance declines for all cognitive and physical tasks as childhood socioeconomic position decreased. For all but one of the cognitive and physical tests, the difference between the top and bottom of the socioeconomic position range was between 7 and 13 percent. The exception to this was verbal memory, which showed a 20 percent difference between the top and bottom of the childhood socioeconomic position range. These patterns were consistent across both genders. To measure the combined impact of all of the factors measured, the researchers created an index of inequality and this combined index indicated a 66 percent relative difference overall between the top and bottom of the childhood socioeconomic range.
Looking at adult socioeconomic position, there were also performance declines across all tasks as adult socioeconomic status decreased. Most of these differences ranged between 6 and 13 percent, but there were more tests that showed larger differences between the top and bottom of the socioeconomic range. These were tests of lung function (16 percent), standing balance (18 percent), and verbal memory (27 percent). In the researchers’ index of inequality, the relative difference between the top and bottom of the socioeconomic range was 74 percent.
Most importantly, the researchers examined the contribution of childhood socioeconomic position while controlling for the participants’ adult socioeconomic position. This answers the important question of whether the impact of low childhood socioeconomic position can be overcome with a rise of socioeconomic status in adulthood. When adjusted for adult socioeconomic position, the researchers found that the association of childhood socioeconomic position remained. Although the strength of this association was reduced compared to childhood socioeconomic position alone, the association remained sizable. The only test on which a sizable association did not remain was the test of standing balance.
Looking at the cognitive data collected in the participants’ childhood, the researchers found that childhood cognitive ability and participants’ educational attainment explained a considerable amount of the childhood socioeconomic position’s association with later physical and cognitive performance. Adult height also proved to be a significant factor in the association between childhood socioeconomic position and performance on physical tests of lung function and physical strength.
The authors posit that this data analysis suggests that strategies for combating the negative impacts of childhood socioeconomic position need to be long term, and that they need to combat the factors that look to link socioeconomic circumstances early in life to health in old age. They conclude the study by stating that “a life course approach to healthy aging is required,” but this research also suggests that it is important for the field of gerontology to take into account the childhood socioeconomic position of elderly adults since this background and not just socioeconomic position at the time of retirement is associated with both cognitive and physical health.
Hurst L, Stafford M, Cooper R, et al. Lifetime socioeconomic inequalities in physical and cognitive aging. American Journal of Public Health (2013); Vol. 103 (9): 1641–1648.