Brain functions differently in people with depression

By Jim Dryden

School of Medicine neuroscientists have identified a key difference in the way the brain functions in people who are depressed compared with those who are not.


The work suggests individuals with depression may not be able to "lose themselves" in work, music, exercise or other activities that enable most healthy people to get "outside" of themselves.

"When healthy people engage in a very focused activity, they, in a sense, lose themselves," said senior investigator Marcus E. Raichle, M.D., whose research group in 2001 first identified the default mode network. "If you really are engaged in something, you kind of forget yourself, and that loss of self corresponds to the deactivation we observe in brain scans of the default network. But that doesn't seem to happen in the brains of people with depression."

Raichle, a professor of radiology, of neurology, of neurobiology, of biomedical engineering and of psychology in Arts & Sciences, said one characteristic of the default network is that it tends to involve self-referential functions. For example, it may involve memories, not just memories of facts or information but about our own experiences and how they relate to that information — the difference between remembering that hijacked planes crashed into the World Trade Center Sept. 11 and remembering where you were when you watched or heard about the attack.






"Some parts of the default network, such as the brain's amygdala, are related to emotion," said Yvette I. Sheline, M.D., professor of psychiatry and the study's first author. "And emotional pictures made those regions more active in depressed people. Meanwhile, other structures that normally deactivate did not deactivate as much. They weren't able to shut down in the same way as a normal person's brain."

As she continues this research, Sheline is looking at the brains of depressed people following treatment with antidepressant drugs. Preliminary results suggest that their default networks function more normally.

She's also planning to test cognitive behavior therapy to see whether it might help "reset" the brain's default network in people with depression.

"People with depression often suffer from cognitive distortions," Sheline said. "This is the thinking that leads from the idea that 'I made a mistake' to the notion that 'I am a bad person.' Cognitive behavior therapy gives people tools to fight against that kind of thinking and reorient themselves in ways that make them less vulnerable to depressive thoughts."

The hope, she said, would be that treatment — with medication, cognitive behavior therapy or both — might help deactivate overactive brain regions that keep depressed people embroiled in depressive thoughts and reset the brain to function more normally.