The BDNF polymorphism is associated with psychiatric symptom among newly diagnosed diabetic patients

Abstract

The prevalence of depression in diabetic patient is approximately twice than in the general population. The brain-derived neurotrophic factor(BDNF) is one of the neurotrophic factor family and plays an important role in neurogenesis and neuro-protection. Some studies have suggested that BDNF plays an anti-diabetic role as well as its role in the psychiatric symptoms. The BDNF polymorphism is known to contribute to psychiatric illness such as depression and anxiety. However, little is known about the impact of the BDNF gene polymorphism in diabetes. In this study we investigated whether the BDNF Val/66/Met polymorphism, glucose status, psychological susceptibility and resilience contribute to development of anxiety or depression symptom in newly diagnosed Korean diabetic patients. We examined biochemical factors and the BDNF polymorphism in 89 newly diagnosed diabetic subjects. Psychiatric symptoms were investigated by the Hospital Anxiety and Depression Scale (HADS). We intended to analyze stress that the patients might have from perspectives of psychological resilience and susceptibility by using resilience scale(CD-RISC) and impact of event scale(IES). Independent samples t-test and chi-square test were used to assess the differences between groups. Pearson’s correlation analysis and logistic regression analysis were conducted to investigate significant factors associated with anxiety and depressive symptom. Sixty-two out of the eighty-nine were found to be Met-carriers. No significant differences were found between Val/Val homozygotes group and Met-carrier group regarding age, sex, BMI and clinical factors related to glycemic control and lipid profile. HADS-anxiety(Met carrier 5.76 ± 3.24; Val/Val homozygote 4.22± 2.59, p-value=0.03) and HADS-depression(Met carrier 6.73 ± 3.44; Val/Val homozygote 4.78 ± 2.59, p-value=0.01)scale in Met-carrier group were higher than Val/Val homozygotes group. IES factor scores in Met-carrier group were also higher than those in Val/Val homozygotes group(Met-carrier vs. Val/Val homozygote; hyperarousal: 12.95± 10.12vs6.51± 5.97, P<0.01; Avoidance12.66± 7.59 vs. 7.07± 4.64, P<0.01; Intrusion 6.67± 5.60 vs. 4.03± 3.79, P=0.012; Sleep problem6.32± 4.86 vs. 2.96± 3.50, P<0.01).HbA1c and depressive symptom showed significant inverse correlation (pearson’s correlation coefficient R=-0.227; P=0.035), however, anxiety symptom and HbA1c had no significant correlation. Resilience factors showed significant inverse correlations and IES factors showed positive correlation with depressive symptom severity(self-efficacy R=-0.389, p<0.001; self-confidence R=-0.462, p<0.001; optimism R=-0.448, p<0.001; self-control R=-0.46, p<0.001; hyperarousal R=0.363, p<0.001; avoidance R=0.219, p=0.039; intrusiveness R=0.257, p=0.015; sleep problem R=0.419, p<0.001). Anxiety symptom and psychological factors also showed similar correlation patterns(Self-confidence R=-0.236, p=0.026; Self-control R=-0.253, p=0.017; hyperarousal R=0.5,p<0.001; avoidance R=0.323,p=0.002; intrusion R=0.337,p=0.001; sleep problemR=0.476,p<0.001).In the final logistic regression analysis model, depressive symptom have significant associations with HbA1c(OR=0.671) and BDNF polymorphism (OR=5.413) whereas hyperarousal was the only variable that proved to be associated with anxiety(OR=1.386). These results suggest that the depressive symptom is related to presence of the Met-allele and lower HbA1c whereas anxiety symptom is related to hyperarousal in newly diagnosed diabetic patients.