Is there a difference between the brain of an atheist and the brain of a religious person?

—Emma Schachner, Utah

Andrew Newberg, director of research at the Myrna Brind Center of Integrative Medicine at Thomas Jefferson University and Hospital in Philadelphia, responds:

RESEARCHERS HAVE pinpointed differences between the brains of believers and nonbelievers, but the neural picture is not yet complete.

Several studies have revealed that people who practice meditation or have prayed for many years exhibit increased activity and have more brain tissue in their frontal lobes, regions associated with attention and reward, as compared with people who do not meditate or pray. A more recent study revealed that people who have had “born again” experiences have a smaller hippocampus, a part of the brain involved in emotions and memory, than atheists do. These findings, however, are difficult to interpret because they do not clarify whether having larger frontal lobes or a smaller hippocampus causes a person to become more religious or whether being pious triggers changes in these brain regions.

Various experiments have also tried to elucidate whether believing in God causes similar brain changes as believing in something else. The results, so far, show that thinking about God may activate the same parts of the brain as thinking about an airplane, a friend or a lamppost. For instance, one study showed that when religious people prayed to God, they used some of the same areas of the brain as when they talked to an average Joe. In other words, in the religious person's brain, God is just as real as any object or person.

Research also suggests that a religious brain exhibits higher levels of dopamine, a hormone associated with increased attention and motivation. A study showed that believers were much more likely than skeptics to see words and faces on a screen when there were none, whereas skeptics often did not see words and faces that were actually there. Yet when skeptics were given the drug L-dopa, which increases the amount of dopamine in the brain, they were just as likely to interpret scrambled patterns as words and faces as were the religious individuals.

So what does the research mean? At the moment, we do not have a clear way to connect all the dots. For now we can say that the religious and atheist brains exhibit differences, but what causes these disparities remains unknown.

How do our thoughts influence our physical sensations?

—Davide Razzoli, Italy

Jeannine Stamatakis, an instructor at several colleges in the San Francisco Bay Area, explains:

YOU MAY have noticed that when you think positively, you tend to feel more relaxed and energetic. When you are upset, you are more likely to feel tired and lazy. These sensations are not coincidental. The way we think—our attitudes and outlook on life—strongly affects our physical state.

The endocrine system, a network of glands that secretes different hormones into the bloodstream, is the powerhouse that regulates our moods. The feelings you associate with being angry, for example, arise from the stress hormones, such as cortisol and norepinephrine, that your brain releases on registering indignation. These hormones release stored energy and increase the amount of blood flowing to your muscles, which in turn elevates your heart rate, blood pressure and breathing while shutting down key metabolic processes, such as digestion and growth.

Similarly, endorphins alter your happiness. An endorphin release causes a natural high, commonly known as an endorphin rush or a runner's high. This high is associated with elevated mood and reduced pain. A brain-imaging experiment by neuroscientist Henning Boecker of the University of Bonn in Germany showed that after highly conditioned male athletes completed two hours of endurance running, they exhibited elevated levels of endorphins in their brain and that an increase in these hormones was associated with the runners' intense feelings of euphoria.

In short, making an effort to think positively, even if doing so feels like a strain, is vital to keeping your body healthy. Take the uplifting example of Norman Cousins, former editor of the now defunct Saturday Review. Cousins was told that he had ankylosing spondylitis, a painful and degenerative spine disease that typically affords sufferers a one-in-500 chance of survival. His doctor predicted that he had six months to live, but Cousins refused to accept the diagnosis. He surrounded himself with family and friends, watched numerous comedy films and sought out positive affirmations. Cousins ended up beating the odds and lived 26 years after his diagnosis. Although it is impossible to know whether his survival hinged on his positive thinking rather than genetic or medical factors, Cousins's case suggests that an intensely optimistic outlook can help alter physical health.