Boston, MA -- One of the features of aging is memory loss, which can have devastating effects on the quality of life among older people. In a new study, Harvard School of Public Health (HSPH) researchers found evidence that elderly people in the U.S. who have an active social life may have a slower rate of memory decline. The study appears in the July 2008 issue of the American Journal of Public Health and appears in an advance online edition on May 29, 2008.
"We hope this study adds to and advances our growing understanding of the important role that social forces play in shaping health," said Karen Ertel, postdoctoral fellow in the Department of Society, Human Development and Health at HSPH.
Previous studies have suggested that an active social life may reduce the risk of dementia and cognitive decline among the elderly. Memory loss is a strong risk factor for dementia, a syndrome estimated to affect up to 10% of the U.S. population 65 years and older. The researchers wanted to test whether memory loss might also be associated with social connectedness.
Ertel and her HSPH colleagues, senior author Lisa Berkman, chair of the Department of Society, Human Development and Health, and Maria Glymour, assistant professor, Department of Society, Human Development and Health, used data gathered from 1998 to 2004 from the Health and Retirement Study, a large, nationally representative population of U.S. adults 50 years and older. (Previous studies were conducted outside of the U.S. or using smaller, non-representative population samples.) Memory was assessed in 1998, 2000, 2002 and 2004 by reading a list of ten common nouns to survey respondents, then asking them to recall as many words as possible immediately and after a five-minute delay. Social integration was assessed by marital status, volunteer activities, and contact with parents, children and neighbors.
The results showed that individuals with the highest social integration had the slowest rate of memory decline from 1998 to 2004. In fact, memory decline among the most integrated was less than half the rate among the least integrated. These findings were independent of sociodemographic factors (such as age, gender, and race) and health status in 1998. The researchers found that the protective effect of social integration was largest among individuals with fewer than 12 years of education.
The researchers found no evidence that the results could be due to reverse causation, that is, poor memory or memory decline causing social withdrawal.
"Social participation and integration have profound effects on health and well being of people during their lifetimes," said Berkman. "We know from previous studies that people with many social ties have lower mortality rates. We now have mounting evidence that strong social networks can help to prevent declines in memory. As our society ages and has more and more older people, it will be important to promote their engagement in social and community life to maintain their well being."
Memory loss and dementia pose a major public health burden among the elderly U.S. population. The results suggest that increasing social integration may help slow memory decline among older Americans and could help alleviate the public health burden, particularly because the aging population in the U.S. is expected to increase substantially. "We need to understand more about how social integration reduces the risk of memory decline in order to target interventions that can help slow the decline," said Ertel. "Future research should focus on identifying the specific aspects of social integration most important for preserving memory."
Support for the study was provided by the National Institute of Aging.
"Effects of Social Integration on Preserving Memory Function in a Nationally Representative U.S. Elderly Population," Karen A. Ertel, M. Maria Glymour, Lisa F. Berkman, American Journal of Public Health, July 2008, Vol. 98, No. 7.
Harvard School of Public Health (www.hsph.harvard.edu) is dedicated to advancing the public's health through learning, discovery, and communication. More than 400 faculty members are engaged in teaching and training the 1,000-plus student body in a broad spectrum of disciplines crucial to the health and well being of individuals and populations around the world. Programs and projects range from the molecular biology of AIDS vaccines to the epidemiology of cancer; from risk analysis to violence prevention; from maternal and children's health to quality of care measurement; from health care management to international health and human rights. For more information on the school visit: www.hsph.harvard.edu