Serotonin Release, Not Levels, May Be Key to Understanding Depression

For a very long time, depression was thought to be caused by low serotonin levels in the brain, a situation dubbed chemical imbalance. But in 2023, the chemical imbalance theory was debunked. However, SSRI antidepressants (drugs believed to increase serotonin levels) still work pretty well for depression.

So, if increasing serotonin levels reverses depression, how can we say lower serotonin levels didn't cause it in the first place?

A new study has found that the real issue surrounding depression is not serotonin levels but how well the available serotonin is released and used by the brain cells.

To study serotonin in the brain, the researchers had to create a tool that allowed them to differentiate between serotonin and other very similar chemicals in the brain. Telling them apart had always been a problem, making it difficult to study the hormone independently.

The researchers found something shocking. The serotonin level in a depressed brain was virtually equal to that in a healthy brain. So obviously, serotonin level wasn't the issue. However, the depressed cells released much less serotonin in response to stimulation.

When selective serotonin reuptake inhibitors (SSRI) antidepressants were administered, the release increased.

So, what could be hindering this serotonin release, leading to depression? The hypothesis points at mTOR, a biomolecule involved in cellular signaling.

That's because, in the presence of mTOR activators, serotonin release increased. On the other hand, mTOR inhibitors reduced serotonin release.

The bottom line

The study proves what we discovered since the chemical imbalance theory was debunked: serotonin level is not the primary factor causing depression.

The brain's ability to release available serotonin may be a more crucial factor. And knowing how mTOR is involved with serotonin release can help in developing more effective treatments for depression.

If you have depression and you're yet to begin treatment, contact us today at Hope Mental Health.

Author

Satu H. Woodland, PMHCNS-BC, APRN Satu Woodland is owner and clinician of Hope Mental Health, an integrative mental health practice located at Bown Crossing in Boise, Idaho. She sees children, adolescents, and adults.  Ms. Woodland with her background in nursing, prefers a holistic and integrative approach to mental health care that addresses the mind and body together. While Ms. Woodland provides medication management services in all her patients, she believes in long-lasting solutions that include a number of psychotherapies, namely cognitive behavioral therapy, exposure and response prevention therapy, attention to lifestyle, evidenced based alternative psychiatric care and spirituality. If you’d like to gain control over your mental health issues, call Hope Mental Health at 208-918-0958, or use the online scheduling tool to set up an initial consultation.