For decades, many people in the public, clinicians, and the scientific community have accepted the “chemical imbalance” explanation of depression. However, a new study by review by Moncreiff et al (2022) challenges this long-held belief. Their comprehensive review found scant evidence linking low serotonin levels to depression. This finding has significant implications for understanding and treating this complex mental health condition and casts doubt on the serotonin theory of depression.

The theory:

The serotonin theory of depression proposes that low levels of the neurotransmitter serotonin cause depression symptoms. This theory has influenced public perception and treatment approaches for many years. However, the lack of robust scientific evidence supporting this theory has raised concerns among researchers.

The study setup:

Moncreiff and colleagues conducted a meticulous review of existing research on serotonin and depression. They analyzed data from 17 diverse studies, including systematic reviews, meta-analyses, and genetic studies.

Study results cast doubt on serotonin theory of depression:

  • The review found no consistent evidence to support the link between low serotonin and depression.
  • Studies examining serotonin metabolites, plasma serotonin levels, and receptor activity did not show a clear connection to depression.
  • Interestingly, some evidence suggests that long-term antidepressant use might actually decrease serotonin levels.
  • Genetic studies also failed to find a significant association between the serotonin transporter gene and depression.

Beyond the Headlines:

These findings challenge the oversimplification of depression as a solely “chemical imbalance”. While further research is needed, this study highlights the importance of considering broader factors that contribute to depression, such as psychological, social, and environmental influences.

Moving Forward:

Understanding the limitations of the serotonin theory can pave the way for more holistic and individualized approaches to treating depression. This includes exploring a wider range of therapeutic options, including therapy, lifestyle modifications, and alternative treatment modalities.

If you or someone you know is struggling with depression, it’s crucial to seek professional help. A mental health professional can provide personalized guidance and support to develop an effective treatment plan. You can find an ACEP-aligned clinician here.

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Author bio:

Sarah Murphy, LPC, ACP-EFT, is an ACEP board member and communications committee chair. She is a counselor in private practice and specializes in working with people who have serious illnesses. A student of the Ageless Wisdom, she is dedicated to sharing the Great Invocation.