Pain, depression, and poor quality of life in chronic pancreatitis: Relationship with altered brain metabolites.

Background: To evaluate if altered brain metabolites are connected to pain, depression and affective responses in CP.

Methods: In this prospective study we evaluated pain characteristics, QOL (EORTC QLQc30+PAN28), depression (Beck depression inventory [BDI] II) in 558 patients with CP and 67 healthy controls. Brain metabolites were evaluated using magnetic resonance spectroscopy (MRS) in 49 patients and 5 healthy controls. We measured plasma metabolites using gas chromatography-mass spectrometry (GC-MS/MS). Relationship between metabolomic alterations, pain, depression and QOL components were assessed using statistical/bioinformatics methods. Benjamini-Hochberg FDR correction was applied for multiple testing.

Results: 261 (46.8%) patients had depression compared to 5 (7.5%) among healthy controls [n = 67](p < 0.0001). Risk [OR (95% CI) of developing depression in the presence of pain was 1.9 (1.33-1.68); p = 0.0004. The depression scores correlated negatively with functional components and positively with symptom components of EORTC QLQ30. Significant negative correlation, though based on a small sample size, was observed between N-acetyl aspartate in the left hippocampus and choline in the left prefrontal cortex with emotional and cognitive functions. PLS-DA modelling revealed significant alteration in the plasma metabolomic profile among patients with CP who had depression. Six metabolites were significantly different between CP with depression and healthy controls, of which glycine contributed most significantly to the PLS-DA model (VIP score of 3.5).

Conclusions: A significant proportion of patients with CP develops depression that correlate with poor QOL functions. Pain, depression, and emotional components of QOL in patients with CP correlated with N-acetyl aspartate and choline in the left hippocampus and left prefrontal cortex of the brain.