NPY and POMC neuropeptide levels are significantly lower in both bipolar and unipolar depression patients | Research

The takeaway

Serum NPY and POMC levels were significantly lower in both unipolar and bipolar depression patients compared to controls (p=0.001), though levels did not significantly differ between the two mood disorder types.

NPY + POMC reduced in depression
Both neuropeptides were significantly lower in unipolar and bipolar depression patients compared to healthy controls, suggesting shared stress-response dysregulation

What the researchers found

NPY and POMC: significantly lower in both UP and BP vs controls (p=0.001). NPY: lower in UP vs BP (NS). POMC: lower in BP vs UP (NS). No correlation with HAM-D, sleepiness, or eating scales.

Why it matters

Identifying neuropeptide biomarkers that are altered in mood disorders could enable objective diagnostic testing and reveal new therapeutic targets, especially given the difficulty of distinguishing bipolar from unipolar depression clinically.

How the study worked

Case-control study: 26 UP + 28 BP patients + 27 healthy controls. Serum NPY and POMC quantification. HAM-D, Epworth Sleepiness Scale, Three-Factor Eating Questionnaire.

What this study cannot tell us

Small sample sizes. Serum levels may not reflect brain neuropeptide concentrations. Cross-sectional—cannot determine causation. Medication effects not fully controlled. No significant differentiation between BP and UP.

How to read the evidence

Small case-control study. Significant findings but needs replication in larger cohorts. First to examine NPY/POMC with eating behavior in mood disorders.

When this study was published

Published in 2025.

The bigger picture

This adds to evidence that mood disorders involve fundamental changes in neuropeptide signaling. The shared NPY/POMC reduction across bipolar and unipolar depression may reflect a common stress-related mechanism rather than a disease-specific marker.

Questions still open

Could NPY/POMC levels help predict treatment response in mood disorders?
Do levels change with treatment response?
Are the reductions a cause or consequence of mood disorders?

Common questions

What are NPY and POMC?

NPY (neuropeptide Y) regulates stress responses, appetite, and mood. POMC (proopiomelanocortin) is a precursor for multiple hormones involved in stress response and metabolism. Both were significantly reduced in depression patients, suggesting that mood disorders involve disrupted neuropeptide signaling.

Could blood tests for these peptides diagnose depression?

Not yet. While both NPY and POMC were lower in depressed patients, the levels did not distinguish between bipolar and unipolar depression—a key clinical challenge. The findings support further research but are not ready for diagnostic use.

Read the original research

Evaluation of Proopiomelanocortin (POMC) and neuropeptide Y (NPY) levels in bipolar and unipolar patients.

BMC psychiatry, 25(1), 707

View on PubMed ↗Publisher’s paper ↗

Citation

Solak, Hatice; Gokcen, Onur. (2025). Evaluation of Proopiomelanocortin (POMC) and neuropeptide Y (NPY) levels in bipolar and unipolar patients.. BMC psychiatry, 25(1), 707. https://doi.org/10.1186/s12888-025-07147-x