Depression is a diagnosis that typically includes a variety of symptoms besides being sad. Some individuals may suffer anxiety while others could have poor attention, problems concentrating, memory issues and sleep difficulties.
A new UCLA study discovers that the variety of symptoms may stem from a malfunction involving brain networks — the connections that link different brain regions. Rather than not having enough brain connections, researchers have shown that people with depression have increased connections among most brain areas.
In the report, published in the online journal PLoS One, UCLA scientists present their new findings on the brain dysfunction that causes depression and its wide array of symptoms.
“The brain must be able to regulate its connections to function properly,” said the study’s first author, psychiatrist Dr. Andrew Leuchter. “The brain must be able to first synchronize, and then later desynchronize, different areas in order to react, regulate mood, learn and solve problems.”
The depressed brain, Leuchter said, maintains its ability to form functional connections but loses the ability to turn these connections off.
“This inability to control how brain areas work together may help explain some of the symptoms in depression,” he said.
Researchers studied the functional connections of the brain in 121 adults diagnosed with major depressive disorder, or MDD. They measured the synchronization of electrical signals from the brain — brain waves — to study networks among the different brain regions.
The UCLA team used a new method called “weighted network analysis” to examine overall brain connections. They found that the depressed subjects showed increased synchronization across all frequencies of electrical activity, indicating dysfunction in many different brain networks.
This finding, they said, supports the current theory that a biochemical imbalance causes depression. Brain rhythms in some of these networks regulate the release of serotonin and other brain chemicals that help control mood, said Leuchter.
“The area of the brain that showed the greatest degree of abnormal connections was the prefrontal cortex, which is heavily involved in regulating mood and solving problems,” he said.
“When brain systems lose their flexibility in controlling connections, they may not be able to adapt to change.
“So an important question is, to what extent do abnormal rhythms drive the abnormal brain chemistry that we see in depression? We have known for some time that antidepressant medications alter the electrical rhythms of the brain at the same time that levels of brain chemicals like serotonin are changing.
“It is possible that a primary effect of antidepressant treatment is to ‘repair’ the brain’s electrical connections and that normalizing brain connectivity is a key step in recovery from depression. That will be the next step in our research.”