Neurohemodynamic correlates of BDNF gene expression in schizophrenia patients with working memory deficits: A functional MRI study

Introduction: Brain-derived neurotrophic factor (BDNF) is involved in neuroplasticity underlying cognitive def-icits, including working memory deficits (WMD), in schizophrenia. Methodological challenges and in-consistencies are reported with peripheral BDNF levels. Left dorsolateral prefrontal cortex (DLPFC) is proposed to underlie WMD, though inconsistently. We aimed to explore the correlations between brain activation during working memory task-based functional Magnetic Resonance Imaging (fMRI) and BDNF gene expression in schizophrenia patients with WMD.Methods: 26 patients with schizophrenia with established WMD were recruited for the study. Blood samples were collected to study lymphocyte BDNF gene expression. Patients underwent task-based fMRI to examine the working memory performance and related brain activation. Whole-brain analysis was performed with 2-back > 0-back and 2-back > rest contrast. The peak intensity values of the activation were used for correlation analysis.Results: Whole brain analysis with 2-back > rest contrast revealed maximum activation in left DLPFC, Brodmann area 9 (t = 10.54, FWE corrected p < 0.05). The baseline BDNF gene expression correlated positively with the peak intensity of brain activation in left DLPFC (r = 0.365, p = 0.033). Negative symptom score negatively correlated with BDNF gene expression (r =-0.499, p = 0.005) and left DLPFC fMRI activation (r =-0.393, p = 0.023) respectively.Conclusion: We found a significant positive association between BDNF gene expression and the activation of the DLPFC during the working memory task. This novel observation needs further systematic evaluation to establish the potential role of peripheral BDNF expression in WMD in schizophrenia.

Automated summary

The study found a significant positive association between BDNF gene expression and DLPFC activation during the working memory task. In addition, BDNF gene expression negatively correlated with negative symptom scores and left DLPFC fMRI activation.