In case you wondered, as I did, about those saints who had a vision of the Virgin, or Jesus, or any of the apostles, you are not alone. Even allowing for frauds who wanted to capitalize on the publicity, there are some cases that are truly compelling. Take Jean D’Arc; this young girl had no ax to grind. There was really nothing in it for her. She went up against the King and the corrupt French nobility of the time to fight the British invaders, who enjoyed an overwhelming military advantage. She heard voices of Jesus and the Virgin Mary exhorting her to lead France against the invaders, which we could easily dismiss as schizophrenic auditory hallucinations. Except that her behavior, other than the religious aspect, is not consistent with this diagnosis. Of course, we’ll never know. We can’t subject the poor girl to a battery of diagnostic tests, because she is definitely and terminally unavailable. Even her body cannot be exhumed for a DNA sample –the church saw to it when it condemned her to burn at the stake.

But we can attack the problem indirectly. For instance, examine the brains of people who underwent a “religious experience”, an epiphany.

Religion is considered an important part of life for many Americans, with 92% reporting a belief in God or a universal spirit, 83% belonging to a religious group, and 59% reporting that they pray at least daily. So it is quite surprising that very few studies even attempted to find a neuroanatomical relationship to religiosity. One could plausibly argue that religious beliefs are purely psychologically and sociologically based, and hence an anatomical correlate is unlikely. But what about people who experience a “religious event”, such as a vision of God, or an inner voice commanding them to adopt certain religious beliefs, (or to run for political office)? These kinds of phenomena, after all, are part of a diagnosis of schizophrenia.

A Word about the Hippocampus

The Hippocampus is a sea horse- shaped area in the brain. It has several important functions, including spatial (“the fiddler was sitting on the roof”), contextual (“in the Chagall painting I saw in the Museum”), and episodic (“his phone number is…”) learning and memory. The hippocampus may also influence the generation of attention and emotion through connections with the amygdala (almond-shaped structures where emotions are formed and stored), and coordinates cortical arousal and responsiveness through interconnections with the amygdala, hypothalamus, prefrontal cortex, and other areas. Studies have also shown that the hippocampus is potentially involved in religious beliefs and spiritual practices. For instance, some findings indicate that the hippocampus is activated during meditation, and that larger hippocampal volumes are associated with long-term meditation practice. On the other hand, among certain epilepsy patients, smaller hippocampal volumes have also been associated with hyper-religiosity. Other factors that are associated with hippocampal volume loss are chronic exposure to cortisol, the stress hormone, and aging. So how does religiosity affect hippocampal volume?

The Duke Study

At long last, somebody did tackle the issue (PLoS ONE, March 30, 2011). A team of scientists from Duke University, led by Amy Owen, conducted a very careful study of the relationship between religious factors and structural neuroanatomy. Specifically, this study examined prospective relationships between religious factors and hippocampal volume change using high-resolution MRI data of a sample of 268 older adults. Participants included two groups, those meeting criteria for major depressive disorder and never-depressed comparison participants. Religious factors assessed included life-changing religious experiences, spiritual practices, and religious group membership. MRI scans were acquired every two years, and religious, psychosocial, and demographic data were collected at baseline and annually, using a structured psychiatric interview. And the results:

  • Those reporting having had life-changing religious experiences showed significantly greater hippocampal atrophy. Although the exact mechanism (parietal lobe seizure? dementia?) has not been determined in this study, the finding is hardly surprising.
  • Greater hippocampal atrophy over time was shown by subjects identifying themselves as born-again Protestants, Catholics, or no religious affiliation, as compared to non-born again Protestants. How can these results be explained? The authors suggest that belonging to a religious minority is a source of chronic stress, which manifests itself in increased atrophy of the hippocampus with age. In fact, several studies have shown increased stress in these groups.

I was a bit skeptical until I came across an article in the New York Times (April 3, 2011) describing a Florida high school club of atheists. What struck me was the conscious effort the students had to make “to be nice”, to smile, to avoid antagonizing or even questioning the religious beliefs of their Christian schoolmates. “Mr. Creamer, 47, an English teacher and longtime atheist who grew up in a family of Free Will Baptists, is constantly urging club members to “be friendly, put on those smiles — people don’t expect that from atheists.” Some students had to keep their membership secret from their parents; echoes of “Don’t ask don’t tell”. I can see how belonging to this minority could cause chronic stress in these kids. Unfortunately, the Duke study also predicts that they will pay for their beliefs with real neurological damage.

Dov Michaeli, MD, PhD
Dov Michaeli, MD, PhD loves to write about the brain and human behavior as well as translate complicated basic science concepts into entertainment for the rest of us. He was a professor at the University of California San Francisco before leaving to enter the world of biotech. He served as the Chief Medical Officer of biotech companies, including Aphton Corporation. He also founded and served as the CEO of Madah Medica, an early stage biotech company developing products to improve post-surgical pain control. He is now retired and enjoys working out, following the stock market, travelling the world, and, of course, writing for TDWI.


  1. unless a man is born again, he cannot enter into the kingdom of God. plus the wisdom of God is foolishness to the world.
    Having a relationship with God, and not religion, improves your life, your health, and your mentality.
    ‘Science will always be against God no matter what. you talk about stress in born again believers? really? my experience is that having a true relationship with Christ takes away stress and worry. How many true believers do you ever hear of comiting suicide, murder,fraud, Robbery, etc. very few. Iam talking about true believers.
    Maybe the brain shrinkage they discovers was the result of less indulgance in ungodly lifestyles which add stress. and most likely, the christians they did the test on may not really have those who have been grounded in the word of God.
    just look @ christian kids and no christian kids, on how they conduct themselves. there is a huge difference. most christian kids show respect to elders, value for life, well mannered, compassionate, they have high moral values. etc.
    Iam going to end with this: true christianity does not shrink the brain, it enhances it through rational and peacful thinking.
    Whtever is true, whatever is lovely, whatever is noble, whatever is trustworthy, think on these things, so the good book says. In other words, keys to healthy mindset can be found in the bible.
    Amy owens is wrong on this one. And I have a lot of doubts on her theology.

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