Antidepressants Fail to Affect Protein That Contributes to Depression Recurrences

Future Antidepressants Should Target Monoamine Oxidase A, Researchers Suggest

A common class of antidepressants, selective serotonin reuptake inhibitors (SSRIs), are ineffective at treating a major brain protein that can contribute to recurrences of depression, according to a new study.

As detailed in the Archives of General Psychiatry, researchers have learned that monoamine oxidase A (MAO-A) is highly elevated during clinical depression but unaffected by most antidepressants, potentially explaining why recurrence is a major problem with depression.

Commonly prescribed to treat depression and related disorders like chronic pain, SSRIs work to keep serotonin, a neurotransmitter that affects mood, in the brain longer. However, MAO-A digests serotonin and other brain chemicals that help maintain mood, with high levels of this protein excessively eliminating these chemicals, possibly leading to recurrences of depression.

In this study, researchers observed 62 total patients, including 28 healthy subjects, 16 patients who had a major depressive episode secondary to major depressive disorder, and 18 patients who were recovering from a major depressive disorder.

Using advanced brain imaging technology called carbon 11-labeled harmine positron emission tomography scans to determine levels of MAO-A in different areas of the brain, the researchers scanned subjects with a major depressive episode before and after 6 weeks of SSRI treatment. The researchers also measured MAO-A in the patients recovering from major depressive disorder, and followed up with them for 6 months.

According to the study’s findings, MAO-A was significantly elevated in different areas of the brain during and after SSRI treatment for patients with a major depressive episode as compared to the healthy control group.

Furthermore, MAO-A was also elevated during recovery, with those patients who eventually experienced a recurring episode of depression having higher levels of this protein in certain areas of the brain than those patients who did not have a recurrence.

According to the study’s researchers, these findings reveal the need for future antidepressants to target and produce lower levels of MAO-A.

Earlier this year, another study in the Archives of General Psychiatry noted how antidepressant use in the last decade doubled to approximately 27 million in 2005, with half of those 27 million people using antidepressants for back pain, nerve pain, fatigue, insomnia and other problems as opposed to depression.

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