Researchers recruited adults beginning therapy for depression and/or anxiety. One group was instructed to spend 20 minutes writing letters expressing gratitude (one letter per week for the first three weeks of therapy). The control group started therapy as usual.
Three months later, all participants took part in a gratitude task while having their brains scanned. They repeatedly received cash gifts and were asked to “pay it forward” to a charity to the extent they felt grateful for the gift.
Compared to the controls, the letter writers showed behavioral increases in gratitude meaning they donated more of the money they had been gifted. But more importantly, the brain scans showed their brains had actually changed. Compared to the controls, the letter writers showed both behavioral increases in gratitude and greater brain changes in the medial prefrontal cortex — the part of the brain that affects planning, judgment and decision-making.
In other words, by practicing gratitude, the brains of the letter writers had been “rewired” to feed gratitude more easily -- an effect that lasted longer after the study had ended.