Role of brain-derived neurotrophic factor in aged patients with type 2 diabetes complicated with depression

Abstract

Objective To assess the relationship between brain-derived neurotrophic factor (BDNF) and depression in aged patients with type 2 diabetes (T2DM) and to investigate the etiology of depression in these patients. Methods A total of 241 patients, treated from March 2008 to December 2009, were included in this study. Based on the Center for Epidemiological Studies Depression Scale (CES-D) and Patient Health Questionnaire (PHQ-9) scales, the patients were divided into non-depression DM group (NDDM group, n=187) and depression DM group (DDM group, n=54). Fifty-two cases of healthy volunteers were set as control group (NC group). BDNF Val66Met polymorphism was determined with polymerase chain reaction-restriction fragment length polymorphism analysis (PCR-RFLP). Serum BDNF level was measured by enzyme linked immunosorbent assay(ELISA). The laboratory results were compared among the three groups by using independent-sample t test, one-way analysis of variance and SNK methods. Results The morbidity rate of depression was 22.4% in this patients group, it was 17.7% in male and 27.1% in female. Compared with NDDM group, more patients were female and more complications occurred in DDM group(P 0.05). There was significant differences in BDNF Val66Met polymorphism and allele (Val, Met) frequency among NC, NDDM, DDM groups (χ2=10.970, P<0.05), the frequency of allele Met in NC, NDDM and DDM group was 38.4%, 38.8% and 53.7%; and there were significant differences among the 3 groups(χ2=8.145, P<0.05). The score of PHQ-9 questionnaire in BDNF Val/Val, Val/Met and Met/Met groups was 3.2±0.9, 3.9±1.2 and 8.1±2.7, respectively; there was significant differences among the 3 groups (F=6.520, P<0.01). The serum BDNF level in NC, NDDM and DDM group was (86±10), (80±9) and (77±10) ng/L, respectively; there was significant differences among the 3 groups(F=28.450, P<0.01). Female, loss of spouse, high complication rate, poor blood glucose control, high body mass index and BDNF Val66Met polymorphism were predisposing factor to geriatric T2DM with depression on multivariate regression analysis. Conclusions The serum BDNF level in aged patients with T2DM complicated with depression is lower. BDNF Val66Met polymorphism contributes to the pathogenesy of geriatric T2DM with depression, and BDNF-Val66Met polymorphism is correlated with the severity of depression. Key words: Diabetes mellitus, type 2; Depressive disorders; Aged; Brain-derived neurotrophic factor