Neglected neighbourhoods and untrustworthy neighbours may be bad for your heart.
In a large study of middle-aged adults, Harvard researchers found that women were more likely to develop calcification in their heart arteries if they lived in such deprived environments compared to women who lived in more well-to-do and cohesive neighbourhoods.
Artery calcification is considered an early warning sign of atherosclerosis, the hardening and narrowing of arteries that can increase the risk of heart attack.
"Beyond personal factors such as income, living in poorer and less closely-knit neighbourhoods may raise one's risks of underlying heart disease, starting as early as middle age," lead author Dr. Daniel Kim, of the Harvard School of Public Health in Boston, told Reuters Health in an email.
Interest in social determinants of health has increased in recent years, partially in response to the obesity epidemic and the hunt for policies that could influence behavioural choices. Two recent reports on the subject, including one from the World Health Organisation, highlight the "importance of the contexts and conditions in which people are born, grow, live and work", noted Kim.
In the study
"In (our) study," he added, "we chose to focus on the places where people live and spend a great deal of time: their neighbourhoods."
The economic position of a neighbourhood may be linked to the availability of nutritious food and recreational areas for physical activity. And the social environment within that neighbourhood may impact behaviors, Kim and colleagues note.
To investigate, they looked at data from nearly 3 000 men and women between the ages of 32 and 50 across four urban areas of the U.S. They linked participants' residential addresses from 1995 to 2000 Census data. Heart artery calcification was measured in 2005.
About 11 percent of the women and 29 percent of the men had "silent" or symptomless, heart artery calcification, Kim and colleagues report in the American Journal of Epidemiology.
After accounting for individual factors such as age, race and income, women living in the most deprived quarter of neighbourhoods based on neighbourhood-level Census indicators for income, education and occupation had two and a half times the odds of heart artery calcification compared to those in the most well-to-do quarter.
Similar comparisons among levels of neighbourhood cohesion as rated by individuals' perception of how well their neighbours got along and trusted one another left women at the bottom with nearly double the odds. Further adjustment for smoking and physical activity had little impact on the results.
Men appeared to be less affected by their neighbourhood, with low cohesion only impacting men living in poor neighbourhoods.
Why might women be more sensitive to their local streets and social networks? It may have to do with the greater amount of time they spend in their neighbourhood, Kim said. Women are more likely than men to work part-time and take on domestic roles such as raising a child.
Dr. Nico Dragano, of Heinrich Heine University in Dusseldorf, Germany, found similar neighbourhood effects in a study of slightly older people. "It is shocking to see that even in a younger population than those we investigated, early stages of heart disease in 'healthy' persons cluster in deprived neighbourhoods," he noted in an email to Reuters Health.
Dragano also points to some limitations of the current study, including a concern that the neighbourhood exposures were linked to addresses 10 years prior to the measurement of heart artery calcification.
Kim and colleagues point out that it would take a few years for neighbourhood effects to physically manifest and they acknowledge that young people moving between neighbourhoods could be one possible alternative explanation for their findings.
"If these strong neighbourhood effects are in fact present," said Kim, "interventions and policies to reduce the gaps in neighbourhood social and economic conditions may serve as powerful ways to address the higher risks of heart disease as well as of other diseases that those living in poorer neighbourhoods disproportionately appear to face. - (Lynne Peeples, Reuters Health, July 2010)