It's not all bad news if you're suffering from depression and you're mulling over your problems, over and over, to the point where you can think of little else.

New research from McMaster University and the Centre for Addiction and Mental Health (CAMH) shows such ruminating might actually be useful.

Researchers offered a new 20-question test to 600 people and found that those with symptoms of depression were actually analyzing their problems, and that such musing was actually a mental adaptation to help them cope with their problems. The findings are in a new paper called “Measuring the bright side of blue.”

“Depression has long been seen as nothing but a problem,” said Paul Andrews, an assistant professor of psychology, neuroscience and behaviour at McMaster, in a release.

“We are asking whether it may actually be a natural adaptation that the brain uses to tackle certain problems. We are seeing more evidence that depression can be a necessary and beneficial adaptation to dealing with major, complex issues that defy easy understanding.”

In an interview with CBC Hamilton, Andrews said ruminating is commonly linked to bouts of depression. But the study shows such focused thinking might be an adaptive way for depression sufferers to work out their problems.

Clinical depression is a serious mental health condition, he told CBC. But these findings may be heartening for depression sufferers, and help mental health professionals better understand how to treat them.

There are different types of depression, he said. These findings relate to depression born from a specific stressor, such as a break up, illness or loss. In 88 per cent of depression cases, he said, the person has experienced a stressful incident that triggered the state.

When a romantic relationship ends, Andrews said, depression sufferers often find themselves fixating on the issue. While researchers have known for decades that being depressed triggers analytical thoughts, “what we’re beginning to show here is that those intense thoughts are not completely useless," he said.

Six hundred McMaster students formed the study sample and took the 20-question test and analytical rumination. Zachary Durisko, a McMaster researcher and CAMH post-doctoral fellow at CAMH, is doing another study with a clinical sample of the general population. Early results show an even stronger link between depression and analytical thinking, Andrews said.

The study takes researchers one step closer to understanding the thought process of people with depression, said Skye Barbic, also a CAMH post-doctoral fellow, in an interview.

“What came out much more clearly is how someone’s thinking when they’re depressed,” she said.

The paper appeared in the journal PLOS ONE.