Feng and his colleagues used functional magnetic resonance imaging (fMRI) to scan the brains of 37 healthy people and 39 people who had received a depression diagnosis but had not sought treatment or responded to antidepressant medication. The makeup of each group was similar in terms of age, sex, and education levels.
In a healthy brain, the waves recorded by fMRI move up and down together in a continuous pattern. But when brain function is disturbed, the waves move out sync with each other—a phenomenon known as “uncoupling.”
The brain waves in the hate circuit were uncoupled in 92% of the depressed patients, the researchers found. Depression was also associated with disruptions in parts of the brain involved in action and risk-taking, emotion and reward-seeking, and attention and memory processing.
Most MRI research in depressed people has treated the brain as a group of discrete regions, by targeting very specific areas or by looking at how regions behave independently. This study, by contrast, observed the entire brain system at once—an approach that helped the researchers spot connections and patterns across multiple regions.
Feng and his colleagues performed the scans while the subjects were resting. This minimized interference from any outside stimuli, but it also means the researchers can’t be sure if the brain disruptions they observed are likely to carry over into active settings, such as social situations.
Further research will be needed to confirm and extend his team’s findings, Feng says. In the future, he says, a focus on the hate circuit may open new avenues for treatment—including new drugs and psychotherapies—that target this and other specific circuits in the brain.
“We might have to think about depression from more wide angles,” he says.
