Health literacy, cognitive ability, and functional health status among older adults

To investigate whether previously noted associations between health literacy and functional health status might be explained by cognitive function.

Health Literacy and Cognition in Older Adults ("LitCog," prospective study funded by National Institute on Aging). Data presented are from interviews conducted among 784 adults, ages 55-74 years receiving care at an academic general medicine clinic or one of four federally qualified health centers in Chicago from 2008 to 2010.

Study participants completed structured, in-person interviews administered by trained research assistants.

Health literacy was measured using the Test of Functional Health Literacy in Adults, Rapid Estimate of Adult Literacy in Medicine, and Newest Vital Sign. Cognitive function was assessed using measures of long-term and working memory, processing speed, reasoning, and verbal ability. Functional health was assessed with SF-36 physical health summary scale and Patient Reported Outcomes Measurement Information System short form subscales for depression and anxiety.

All health literacy measures were significantly correlated with all cognitive domains. In multivariable analyses, inadequate health literacy was associated with worse physical health and more depressive symptoms. After adjusting for cognitive abilities, associations between health literacy, physical health, and depressive symptoms were attenuated and no longer significant.

Cognitive function explains a significant proportion of the associations between health literacy, physical health, and depression among older adults. Interventions to reduce literacy disparities in health care should minimize the cognitive burden in behaviors patients must adopt to manage personal health.