Depression is bad enough, but can be especially tough when the antidepressant drugs a person is prescribed don't work. Doctors and researchers aren't yet sure why this is, and often try different medications or combinations of medications in their efforts to treat depressive symptoms. In addition, the drugs may have unpleasant or even dangerous side effects that prompt patients and their doctors to seek other remedies.

Now the first large-scale study to test cognitive behavioral therapy (CBT) as a supplement to usual depression care has found it effective, easing depression in nearly half of all people who were not helped by antidepressant medications.

The researchers see these results as a confirmation that two different treatment approaches, the psychological and physical, can complement each other when combined and add up to better overall depression treatment.

Cognitive behavioral therapy describes a form of talk-based psychotherapy designed to get people to examine the behaviors, beliefs and thought processes that may be holding them back or contributing to their feelings of depression.

The CoBalT study was a randomized controlled trial of 475 patients, aged 18-75, from 73 different treatment centers in the United Kingdom. All had been diagnosed with antidepressant resistant depression, depression that had not improved after six weeks or more of antidepressant treatment. Half of the study participants continued to receive their usual care and half began to receive CBT in addition to their usual care.

After six months, 46% of the patients who received CBT showed a decrease of at least 50% in their depressive symptoms, compared to 22% of those who continued with usual care alone. The improvement seen in the CBT group remained one full year after CBT began.

The researchers see these results as a confirmation that two different treatment approaches, the psychological and physical, can complement each other when combined and add up to better overall depression treatment. They were also encouraged because CBT worked well across a wide range of people of different ages and living in a variety of settings, indicating widespread usefulness.

But CBT isn't always available to those who need it most. Efforts have been made to increase its availability in countries such as the UK and particularly in Australia, which has had a national online eTherapy service in place since 2008. In other countries, such as the U.S., access to CBT is often limited to those whose health insurance covers it or who can afford to pay for it out of their own pocket.

The researchers hope that the CoBalT study's findings of substantial and long-lasting depression relief are a first step toward making CBT more readily available to patients suffering from depression.

An article on the study was published online in The Lancet on December 7, 2012 and will also appear in a future print issue of the journal.