Low plasma BDNF is not a biomarker for cognitive dysfunction in elderly T2DM patients.

Type 2 diabetes mellitus (T2DM) is a known cause of cognitive dysfunction, and brain-derived neurotrophic factor (BDNF) is a key protein in promoting memory growth and survival of neurons. However, the relationship between plasma BDNF and diabetic cognitive dysfunction is still elusive. A total of 89 patients over 60 years with T2DM and 40 well-matched health controls were enrolled. All participants received a set of multi-dimensional neuropsychological tests for the cognitive assessment. The subjects were divided into amnesic mild cognitive impairment (aMCI) and non-aMCI groups. An enzyme-linked immunosorbent assay (ELISA) was used to measure plasma BDNF concentrations for all subjects. No significant difference was found between T2DM patients and healthy control in MMSE scores. The T2DM patients performed significantly worse in four cognitive domains (including episodic memory, executive function, visuospatial function, and information processing speed) compared with the controls (all p < 0.05). The prevalence of aMCI in T2DM population was higher [OR = 4.032 (1.536~10.582), 37/89-6/40]. Additionally, the plasma concentration of BDNF in T2DM patients was significantly lower than that in controls (p < 0.01). However, no significant correlation was found between plasma BDNF and cognitive function in T2DM. Our results suggested that T2DM have a higher prevalence of cognitive impairment. The plasma BDNF concentration in T2DM patients was significantly lower than that in controls, but low BDNF was not a biomarker for cognitive dysfunction in T2DM patients.

[Study of cognitive function and brain volume in type 2 diabetic patients].

OBJECTIVE: To investigate the differences of cognitive function and brain volume between patients with type 2 diabetes mellitus (DM) and healthy controls. METHODS: Multi-dimensional neuropsychological tests were employed to evaluated cognitive function in 21 type 2 DM patients and 19 healthy controls, and voxel-based morphometry method was applied to measure volume of whole and regional gray matter in brain of these subjects. RESULTS: Compared to healthy controls [(7.3 +/- 1.4), (22.7 +/- 1.2), (9.5 +/- 2.5) respectively], significantly impaired performance of Auditory Verbal Learning Test (AVLT)-Delay Recall, [(5.7 +/- 1.8)] AVLT-Recognition [(20.8 +/- 2.6)] and Clock Drawing Test (CDT) [(8.0 +/- 1.1)] and extensive atrophy of gray matter (after corrected by total intracranial volume) were observed in type 2 DM patients (P < 0.05). In addition, whole gray matter/Total Intracranial Volume (TIV) was significantly negatively correlated with BMI (r = -0.352, P = 0.013). And negative correlations existed between whole gray matter vs HbA1c (r = -0.309, P = 0.026); the performance of AVLT-Delay Recall and AVLT-Recognition vs BMI (r = -0.398, P = 0.011; r = -0.4, P = 0.011)and HbA1c (r = -0.354, P = 0.025; r = -0.323, P = 0.042) and CDT vs HbA1c (r = -0.322, P = 0.043). CONCLUSION: Multi-cognitive impairment was associated with the reduced volume of whole and regional gray matter in brain of type 2 DM patients, which indicated that "accelerated brain ageing" might present in type 2 DM patients.