According to the Los Angeles County Department of Public Health, major depressive disorders are increasing each year in the county and affect more women than men. Symptoms related to depression include anxiety, poor attention and concentration, memory issues, and sleep disturbances. The multitude of related symptoms suggested to UCLA researchers that depression may be related to a malfunction between brain networks linking different sections of the brain. On February 27, they announced that they had determined that depressed individuals suffer from increased connections between brain areas—in a word, they are hyperconnected. The results of their findings were published online in the journal PLos One.
The researchers reported that their study was the largest of its kind to date; it evaluated the functional connections of the brain in 121 adults diagnosed with a major depressive disorder (MDD). They measured the synchronization of electrical signals from the brain (brain waves) in order to evaluate networks connecting different brain regions. “The brain must be able to regulate its connections to function properly,” noted the study’s first author, Dr. Andrew Leuchter, a professor of psychiatry at the Semel Institute for Neuroscience and Human Behavior at UCLA. He added, “The brain must be able to first synchronize, and then later desynchronize, different areas in order to react, regulate mood, learn and solve problems.” He explained that the depressed brain maintains its ability to form functional connections; however, it loses the ability to turn these connections off. He noted that the inability to control how different brain areas work together might explain the underlying mechanisms of depression.
Some previous studies have suggested that abnormal patterns of connections might be present in MDD, the researchers employed a new method called “weighted network analysis” to examine overall brain connections. They found that the depressed individuals exhibited increased synchronization across all frequencies of electrical activity; they noted that this indicated dysfunction in many different brain networks. Dr. Leuchter explained that brain activity in some of these networks regulates the release of serotonin and other brain chemicals that help control mood. He noted, “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… When brain systems lose their flexibility in controlling connections, they may not be able to adapt to change.
He concluded, “[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.”