Associations of decreased serum total protein, albumin, and globulin with depressive severity of schizophrenia

Abstract

Objective: Depression and schizophrenia (SCH) were accompanied by an acute phase response (APR) that was implicated in the alterations in total protein (TP), albumin, and globulin levels. The aims of this study are to examine serum TP, albumin, globulin levels, depressive symptoms, and their associations in patients with SCH.

Methods: We recruited 34 patients with SCH and 136 healthy controls (HCs) according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV). Psychiatric symptoms and biomarkers were assessed using the Chinese version of the Positive and Negative Syndrome Scale (PANSS) as well as the bromocresol green and biuret methods.

Results: Serum TP (F = 46.11, p < 0.001, η2 = 0.19), albumin (F = 31.69, p < 0.001, η2 = 0.14), and globulin (F = 12.48, p < 0.001, η2 = 0.06) levels were lower in patients than those in HCs after adjusting for covariates. Serum TP (r = -0.37, p = 0.03) and albumin (r = -0.37, p = 0.03) levels were negatively correlated with depressive score in patients. Stepwise multivariate regression analysis showed the negative associations of depressive score with serum TP (β = -0.13, t = -2.92, p = 0.007), albumin (β = -0.23, t = -2.36, p = 0.03), and globulin (β = -0.16, t = -2.40, p = 0.02) levels in patients. Serum TP, albumin, and globulin levels exhibited the accuracies of 87.1, 70.0, and 69.4% in discriminating between patients and HCs (area under the curve [AUC]: 0.78, 0.68, and 0.77; sensitivity/specificity: 52.9%/95.6%, 55.9%/73.5%, and 76.5%/67.6%).

Conclusion: Our data suggested that decreased serum TP, albumin, and globulin should be regarded as the SCH risk factors and were implicated in the depressive severity of SCH, which further provided the support for the hypothesis that SCH and depression were accompanied by the abnormal inflammatory cytokines with the APR.

Keywords: albumin; depressive symptom; globulin; schizophrenia; total protein.

FIGURE 1

Comparisons of serum total protein (TP), albumin, and globulin levels between patients with schizophrenia (SCH) and healthy controls (HCs). (A) Serum TP concentrations were markedly lower in patients with SCH than that in HCs after adjusting for covariates (70.01 ± 5.52 vs. 75.84 ± 4.38, F = 46.11, p < 0.001, η2 = 0.19); (B) serum albumin concentrations were markedly lower in patients with SCH than that in HCs after adjusting for covariates (44.14 ± 2.87 vs. 47.01 ± 2.90, F = 31.69, p < 0.001, η2 = 0.14); and (C) serum globulin concentrations were markedly lower in patients with SCH than that in HCs after adjusting for covariates (25.88 ± 3.67 vs. 28.83 ± 4.54, F = 12.48, p < 0.001, η2 = 0.06). TP, total protein; HCs, healthy controls; SCH, schizophrenia; ANCOVA, analysis of covariance; ANOVA, analysis of variance.

FIGURE 2

Correlations of serum TP, albumin, and globulin concentrations with depressive score in patients with SCH, respectively. (A) A negative correlation of serum TP concentration with depressive score was found in patients with SCH (r = –0.37, p = 0.03); (B) a negative correlation of serum albumin concentration with depressive symptom score was found in patients with SCH (r = –0.37, p = 0.03); and (C) serum globulin concentration was not correlated with depressive score in patients with SCH (r = –0.27, p = 0.12). PANSS, the Positive and Negative Syndrome Scale.

FIGURE 3

Receiver operating characteristic (ROC) curves for the classification models were identified schizophrenic diagnosis based on serum TP levels (A), serum globulin levels (B), and serum albumin levels (C). CI, confidence interval; AUC, area under curve.