Frequent attendees also had significantly lower risk both from cardiovascular- and cancer-related mortality.
The study published online May 16, 2016 in JAMA Internal Medicine.
"Our results suggest that there may be something important about religious service attendance beyond solitary spirituality,” said Tyler VanderWeele, professor of epidemiology at Harvard Chan School and senior author of the study. "Part of the benefit seems to be that attending religious services increases social support, discourages smoking, decreases depression, and helps people develop a more optimistic or hopeful outlook on life.”
Nearly 40% of Americans report attending religious services once per week or more. Previous studies have suggested a link between attendance and reduced mortality risk, but many were criticized for major limitations, including the possibility of "reverse causation”—that only those who are healthy can attend services, so that attendance isn’t necessarily influencing health. The new study addressed these criticisms by using rigorous methodology that controlled for common causes of attendance and mortality, used a larger sample size, and had repeated measurements over time of both attendance and health.
The researchers looked at data from 1992-2012 from 74,534 women who participated in the Nurses’ Health Study. The women answered questionnaires about their diet, lifestyle, and health every two years, and about their religious service attendance every four years. The researchers adjusted for a variety of factors, including diet, physical activity, alcohol consumption, smoking status, body mass index, social integration, depression, race and ethnicity.
Compared with women who never attended religious services, women who attended more than once per week had 33% lower mortality risk during the study period and lived an average of five months longer, the study found. Those who attended weekly had 26% lower risk and those who attended less than once a week had 13% lower risk.
The study also found that women who attended religious services once per week or more had a decreased risk of both cardiovascular mortality (27%) and cancer mortality (21%).