Serum brain-derived neurotrophic factor levels in type 2 diabetes mellitus patients and its association with cognitive impairment: A meta-analysis.

OBJECTIVE: To compare the serum levels of brain-derived neurotrophic factor (BDNF) in type 2 diabetes mellitus (T2DM) patients with healthy controls (HC) and evaluate the BDNF levels in T2DM patients with/without cognitive impairment. METHODS: PubMed, EMBASE, and the Cochrane Library databases were searched for the published English literature on BDNF in T2DM patients from inception to December 2022. The BDNF data in the T2DM and HC groups were extracted, and the study quality was evaluated using the Agency for Healthcare Research and Quality. A meta-analysis of the pooled data was conducted using Review Manager 5.3 and Stata 12.0 software. RESULTS: A total of 18 English articles fulfilled with inclusion criteria. The standard mean difference of the serum BDNF level was significantly lower in T2DM than that in the HC group (SMD: -2.04, z = 11.19, P <0.001). Besides, T2DM cognitive impairment group had a slightly lower serum BDNF level compared to the non-cognitive impairment group (SMD: -2.59, z = 1.87, P = 0.06). CONCLUSION: BDNF might be involved in the neuropathophysiology of cerebral damage in T2DM, especially cognitive impairment in T2DM.

Lumbar Spine Bone Mineral Density Measurement: Comparison of Dual-Energy X-Ray Absorptiometry and Fat Content Evaluation by Dixon Chemical Shift MRI.

Background: To assess whether the fat signal intensity and fat fraction (FF) of the lumbar vertebrae as measured on the Dixon chemical shift magnetic resonance imaging (MRI) technique can be correlated with the lumbar vertebra bone mineral density (BMD) measured using dual-energy X-ray absorptiometry (DXA). Methods: Forty-five patients were retrospectively collected, and 180 lumbar vertebral bodies (L1-L4) were included. All patients underwent DXA and MRI examinations of the lumbar spine. Taking the T value of DXA as the gold standard and using the diagnostic criteria of the World Health Organization: T score ≥ -1.0SD as normal, -1.0 ~ -2.5SD as osteopenia, and ≤ -2.5SD as osteoporosis. Meanwhile, the signal intensity on T2WI was measured, and FF of L1-L4 vertebral bodies was calculated on MRI images. Bone marrow fat FF calculation formula: FF = [Mfat/(Mfat + Mwater)] × 100% (Mwater and Mfat refer to the total pixel signal intensity value of the region of interest in water image and lipid image, respectively). Finally, the association of signal intensity and FF with DXA was evaluated. Results: Totally 180 vertebral bodies in 45 patients were enrolled. According to the T value, they were divided into the normal group (n = 70), osteopenia group (n = 40), and osteoporosis group (n = 70). The fat signal intensity of the normal group, osteopenia group, and osteoporosis group were 96.6 ± 21.8, 154.5 ± 48.7, 216.3 ± 92.6, and the FF were 30.1 ± 6.2%, 52.6 ± 7.6%, 77.5 ± 7.9%, respectively. Among the three groups, the lumbar T2 fat signal intensity and FF had statistical differences (P < 0.01). Besides, the lumbar fat signal intensity and FF were negatively related to DXA (r =-0.65 and -0.93, P < 0.01). Conclusion: The fat content calculated using the Dixon chemical shift MRI had an inverse relation with BMD. Moreover, the Dixon chemical shift MRI might provide complementary information to osteoporosis-related research fields.