How your neighborhood, sense of smell, and relationship status can add years to your life.

Differences in older people’s health may have less to do with chronological age than one might assume. New data about aging in America show that factors like a person’s sense of smell or social network can also be central to overall wellness.  

The National Social Life, Health, and Aging Project (NSHAP) is the first in-home study of social relationships and health in a nationally representative sample of older adults (aged 57–85 during the first wave of data collection). Conducted by the independent research organization NORC at the University of Chicago, it has tracked thousands of participants since 2005 and their partners since 2010. 

The project “is really the first survey of its kind to take seriously the role of the social world in health and well-being at older ages,” says Linda Waite, the Lucy Flower Professor in Urban Sociology and principal investigator of NSHAP. “We designed this survey specifically to allow us to use detailed measures of health with many dimensions of the social world, to see how they all work together to determine well-being and life expectancy.”

Focusing on relationships as well as biomeasures such as sensory function, mobility, height, weight, and blood tests, the project is backed by $50 million in funding from the National Institutes of Health over its 20-year lifespan. The project’s multidisciplinary team—120 field interviewers, 10 faculty investigators, 30 researchers at NORC, and another 30 graduate students and postdocs—has produced more than 200 papers representing a cross-pollination between sociology, psychology, epidemiology, biology, public policy, statistics, demography, and medicine.

“The standard medical model is too focused on chronic diseases of organ systems,” Waite says. “This misses a lot of other components of health that have big implications for the life or death of a person.” 

Poor sense of smell, for instance, is actually a bigger harbinger of mortality than other clinical indicators like cancer and heart disease, according to Martha McClintock, the David Lee Shillinglaw Distinguished Service Professor in Psychology. Those who could not identify any common household odors were 30 percent more likely to die in the next five years than those who could. 

Olfactory loss may be partially attributed to a person’s neighborhood context, says Kathleen Cagney, professor of sociology and Director of the Population Research Center at NORC and the University of Chicago. Residents in poorer communities could be exposed to more environmental hazards, such as pollution and airborne toxins, which find a direct path to the brain through the nose.

Cagney also used the survey to explore the effects of neighborhood housing foreclosures on mental health. Participants who lived amid high levels of foreclosure were more likely to become depressed, regardless of their own finances. Older people in disadvantaged neighborhoods in general had greater fear of victimization, which could make them less likely to leave their homes, leading to decreased physical activity and increased social isolation, which is also a predictor of declining health.

The researchers found those with more connected networks were less likely to have undiagnosed hypertension, and NSHAP findings suggest that interventions to reduce loneliness may be more effective in preserving health than those aimed at combating obesity.

The NSHAP survey also demonstrates a link between sexual activity in married couples and their ability to deal emotionally with health problems. “Sex is a relational resource to face the challenges that come with aging,” says Waite, who directs NORC’s Center on the Demography and Economics of Aging. When older Americans get sick, health challenges take less of a toll on their marriage quality if they remain sexually active.

Medical professionals are taking note of the project’s findings. Two physicians wrote a December 2016 letter in the Journal of the American Medical Association adopting NSHAP’s more comprehensive model of wellness. A model that includes health behaviors, global sensory function, mental health, and cognitive and immune function, they concurred, is better at predicting who dies or becomes seriously ill in the near future.

“Aging is a really interesting prism to understand inequality because those markers accrue over one’s life,” says Cagney. “This  takes a long view of aging, and it’s an opportunity to understand how different life trajectories matter.”