Association between decreased serum TBIL concentration and immediate memory impairment in schizophrenia patients

Abstract

Cognitive impairment is a core feature of schizophrenia (SCH). In addition to the toxic effect of Bilirubin (BIL), it has antioxidant properties that were associated with the psychopathology and cognitive impairment of psychiatric disorders. The aim of this study was to examine the correlation of serum total BIL (TBIL) concentration with cognitive impairment in SCH patients. We recruited 34 SCH patients and 119 healthy controls (HCs) in this case-control design. Cognition was assessed using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Serum TBIL concentration was measured using the immunoturbidimetric method. Serum TBIL concentration was significantly decreased in SCH patients compared to HCs after adjusting for age, gender, and education. Serum TBIL concentration in SCH patients was also positively correlated with the RBANS immediate memory score. Further stepwise multiple regression analysis confirmed the positive association between serum TBIL concentration and immediate memory score in SCH patients. Our findings supported that the decline in serum TBIL concentration was associated with the immediate memory impairment and psychopathology of SCH.

Plasma bilirubin levels are reduced in first-episode psychosis patients and associates to working memory and duration of untreated psychosis

“…However, the correlation between bilirubin and WMSIII-LNS were only significant at 10 percent level (see Supplementary Table S5 online). We are hereby able to confirm the findings seen in chronic patients with schizophrenia in the study by Yin et al 24 , but here in individuals with FEP, at the same time addressing the influence of antipsychotic medication, BMI, smoking and alcohol, as requested by the authors 24 .…”

“…Equivalent to our findings, Yin et al found reduced levels of bilirubin in two weeks antipsychotic-free patients with chronic schizophrenia compared with HC 24 . In line with our study, bilirubin was positively correlated with memory, although immediate memory, in individuals with schizophrenia but not in HC.…”

“…Serum bilirubin levels have been positively correlated with cognitive scores in patients with mild cognitive impairment 22 and subcortical ischemic vascular disease 23 . A preliminary finding recently published also found a positive correlation between low levels of bilirubin with immediate memory score in patients with schizophrenia 24 . Several studies have also demonstrated lower levels of bilirubin in these patients compared with HC 9 , 12 , 20 , 24 – 26 .…”

“…A preliminary finding recently published also found a positive correlation between low levels of bilirubin with immediate memory score in patients with schizophrenia 24 . Several studies have also demonstrated lower levels of bilirubin in these patients compared with HC 9 , 12 , 20 , 24 – 26 . Reductions in endogenous antioxidants, such as bilirubin, seen in schizophrenia have been suggested to represent their action as sacrificial molecules while neutralizing reactive oxygen species (ROS) 27 .…”

“…Yin et al emphasized that they were unable to control for potential confounders such as antipsychotics, body mass index (BMI), alcohol intake and smoking in their study and requested future analysis to be performed in antipsychotic naïve individuals with FEP 24 . In the present study the positive correlation between bilirubin and WMSIII-SS remained significant at 5 percent level in our sub group analysis of antipsychotic naïve individuals with FEP (see Supplementary Table S5 online).…”