According to a new study, a simple new method for treating depression could help the millions of people who do not respond to conventional treatments or who are unable to obtain treatment at all. Though the evidence is preliminary, it may bring hope to the many people who suffer from this chronic illness.

After reviewing brain imaging studies, they speculate that PAI might work by enhancing the pleasure-reward system that is shut down in depressed people.

Depression is estimated to affect 100 million people worldwide. Of the over 16 million affected in the United States, only 30% of reported cases get "minimally adequate treatment," according to the NIH. The study authors point out that this implies that 70% get no treatment or inadequate treatment, and this is just the cases that are reported: there are plenty of people who do not seek help because of stigma, lack of care, or unknown reasons. What’s more, with antidepressant medications, only 30-40% of patients achieve remission — and 80% of the drugs’ activity is accounted for by the placebo effect, according to the new study.

But the review study looked at the potential for a treatment known as Positive Activity Intervention (PAI) to help people with mild depression. The authors reviewed previous studies of PAI, which included "writing letters of gratitude, counting one’s blessings, practicing optimism, performing acts of kindness, meditating on positive feelings toward others, and using one’s signature strengths." Most of the studies reviewed used healthy people, but two of the studies looked at participants with mild depression.

The authors found that some depressed participants achieved remission after PAI, which lasted up to six months. After reviewing brain imaging studies, they speculate that PAI might work by enhancing the pleasure-reward system that is shut down in depressed people.

Study author Kristin Layous says that the theory is old, but studying it scientifically is new. "The positive activities themselves aren’t really new. After all, humans have been counting their blessings, dreaming optimistically, writing thank you notes, and doing acts of kindness for thousands of years. What’s new is the scientific rigor that researchers have applied to measuring benefits and understanding why they work."

She and her team also suggest that there is a domino effect in the way that PAI works: "For example," they write, "if a person gets 15 minutes of positive emotions from counting her blessings, she may muster the energy to attend the art class she always considered attending, and, while in class, might meet a friend who becomes a companion and confidant for years to come."

Though the results seem promising, it’s still early, and the phenomenon will need to be tested in people with moderate and severe depression. Still, whether you’re depressed or not, it’s worth giving it try — a little positive thinking in your life may go further than you think.

The study was carried out by a team at the University of California, Riverside, and Duke University. It was published in the July 1, 2011 online issue of The Journal of Alternative and Complementary Medicine.