REUTERS/Kham

The authors of a study suggest that the accelerated hippocampal shrinkage may be the result of the stress associated with being a member of a minority religion.

Science writer Tom Jacobs reports in the online magazine Miller-McCune on the strange findings from a new study on religion and the brain.

According to a team of Duke University researchers, the hippocampus, an area of the brain that plays a key role in learning and memory — and perhaps in religious experiences — and that typically atrophies with age, tends to shrink faster in people whose religion is a) Catholic, b) born-again Protestant or c) non-existent (atheist) than it does in people who are mainline Protestants.

The reason? Well, the authors of the study, which was published last week in the journal PLoS One, suggest that the accelerated hippocampal shrinkage may be the result of the stress associated with being a member of a minority religion. For, as the researchers note, other research has suggested that stress hormones negatively affect this region of the brain.

Holy moly.

Here’s Jacob’s description of the study:

The participants were 268 residents of the American Southeast, all of whom were at least 58 years old when the project got underway. All were involved on an ongoing basis for two to eight years.

MRI scans of their brains were performed every two years; data on their spiritual life and psychological state (including levels of stress and depression) was collected annually. Religion-oriented questions included their specific affiliation (or lack thereof); how often they worship publicly and pray privately; and whether they consider themselves “born again,” or have had any other religious experience that changed their life.

“Significantly greater hippocampal atrophy was observed from baseline to final assessment among born-again Protestants, Catholics, and those with no religious affiliation, compared with Protestants not identifying as born-again,” the researchers report.

The study found no association between the changes in the hippocampus and how often a person attended religious services and functions. But greater shrinkage was observed among people who said they had experienced a life-changing religious experience.

“Spiritual experiences not easily interpreted within an existing cognitive framework or set of religious beliefs have been shown in previous research to be detrimental to subjective well-being,” write the study’s authors. “Such experiences have the capacity to produce doubts regarding previously unquestioned convictions, potentially inducing cumulative stress even if the experience was subjectively positive. If the experience prompts a change in religious groups, existing social networks may also be disrupted. Thus, as possible sources of cumulative stress, both minority religious group membership and life-changing religious experiences may contribute to conditions that are deleterious for hippocampal volume.”

Hmmm. A reasonable person could interpret that statement, I think, as saying that some religions are bad for your brain.

Many limitations
Before you start thinking about changing your religion (or taking up one for the first time, if you’re an atheist), be aware that this study comes with several important caveats. First of all, it's a small, single study. But more important, it’s an observational study, which means it can’t really prove that one thing (a certain religion in this case) causes something else (a smaller hippocampus). It can only show that two things are associated.

Other, unknown factors may have led to the study’s results. “[T]he pool of study participants was ‘geographically and religiously constrained,’ consisting largely of ‘Southeastern Protestant Christians,’ ” Jacobs points out. “Perhaps in a region of the country that is more religiously diverse, or where religion plays less of a role in public life, the stressors on those with minority beliefs might be less pronounced.”

Or maybe stress had nothing to do with it. Maybe this geographically constrained group of people shared some genetic trait (or something in the water?) that caused their hippocampi to atrophy at a faster-than-usual rate.

In any event, Buddhists, who are definitely members of a minority religion in the United States, may not have to worry about being more vulnerable to shrinking hippocampi. Other research has suggested that “meditation, which is a key component of Buddhist religious practice, may counteract this tendency,” reports Jacobs.

You can read his article on the study, or the full study itself.