According to USA Today, the 11-year study, “which included at least two MRI measurements on 268 adults between 1994 and 2005 … found an association between participants’ professed religious affiliation and the physical structure of their brain. Specifically, those identified as Protestant who did not have a religious conversion or born-again experience — more common among their evangelical brethren — had a bigger hippocampus.”
The research, which focused on brain shrinkage among older adults, grew out of a larger project in which participants, all 58 years of age and older, were recruited for a study to determine the effects of depression on the elderly. In the study on believers, “researchers ruled out depression or lack of social support as reasons for the smaller brain size,” reported USA Today.
The study found that those who said that they were a “born-again” Protestant or Catholic, as well as those who claimed no religious affiliation, had more brain atrophy (shrinkage) than participants who identified themselves as non-born-again Protestants.
In trying to make sense of the results of their study, researchers suggested that the stress related to embracing religious convictions not held by the majority may account in part for the smaller brain sizes of “born-again’ participants. Amy Owen, a research associate at Duke University Medical Center and the lead author of the study, said that one explanation for the finding that members of majority religious groups seem to have larger brains than minority religious groups like born-again evangelicals and Catholics “is that when you feel your beliefs and values are somewhat at odds with those of society as a whole, it may contribute to long-term stress that could have implications for the brain.”
The researchers also suggested that “life-changing religious experiences” may challenge an individual’s established convictions, leading to stress. “Other studies have led us to think that whether a new experience you consider spiritual is interpreted as comforting or stressful may depend on whether or not it fits in with your existing religious beliefs and those of the people around you,” explained David Hayward, another of the Duke research associates. “Especially for older adults, these unexpected new experiences may lead to doubts about long-held religious beliefs, or to disagreements with friends and family.”
Meanwhile, wrote Yonat Shimron of Religion News Service, sociologists who study religion remain skeptical of the study’s findings. “They say the researchers’ theory flies in the face of U.S. religious demographics,” wrote Shimron. “While it’s true that evangelicals are a minority, they’re a sizable one — 40% of the U.S. population, according to Gallup Polls — and not exactly a stressed-out minority, especially in the South.” Said David Roozen, a sociologist at Hartford Seminary, “There are probably more born-again Protestants than non-born-again Protestants, and just about as many Catholics as either born-again or non-born-again Protestants.”