Background Retinal biomarkers of Alzheimer’s disease (AD) have been extensively investigated in recent decades. Retinal nervous and vascular parameters can reflect brain conditions, and they can facilitate early diagnosis of AD. Objective Our study aimed to evaluate the difference in retinal neuro-layer thickness and vascular parameters of patients with AD and healthy controls (HCs). Methods Non-invasive optical coherence tomography angiography (OCTA) was used to determine the combined thickness of the retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL), as well as the full retinal thickness (FRT). The vascular branching (VB), vascular curvature (VC), and vascular density (VD) for AD and HC groups were also obtained. The Mini-Mental State Examination (MMSE) was used to evaluate the cognitive performance of all the participants. After obtaining all the parameters, two-way analysis of variance (ANOVA) was used to compare the mean values of all the retinal parameters of the patients with AD and the HCs. Pearson's correlation was used to test the association between retinal parameters, MMSE scores, and vascular parameters. Results Seventy-eight eyes from 39 participants (19 AD and 20 HC; male, 52.6% in AD and 45.0% in HC; mean [standard deviation] age of 73.79 [7.22] years in AD and 74.35 [6.07] years in HC) were included for the analysis. The average RNFL + GCL thickness (106.32 ± 7.34 μm), FRTs of the four quadrants (290.35 ± 13.05 μm of inferior quadrant, 294.68 ± 9.37 μm of superior quadrant, 302.97 ± 6.52 μm of nasal quadrant, 286.02 ± 13.74 μm of temporal quadrant), and retinal VD (0.0148 ± 0.003) of patients with AD, compared with the HCs, were significantly reduced (p < 0.05). Retinal thickness was significantly correlated with the MMSE scores (p < 0.05). Meanwhile, retinal VD was significantly correlated with the average RNFL + GCL thickness (r2 = 0.2146, p < 0.01). When the vascular parameters were considered, the sensitivity of the AD diagnosis was increased from 0.874 to 0.892. Conclusion Our study suggested that the patients with AD, compared with age-matched HCs, had significantly reduced RNFL + GCL thickness and vascular density. These reductions correlated with the cognitive performance of the participants. By combining nerve and vessel parameters, the diagnosis of AD can be improved using OCTA technology. Trail registration Name of the registry: Chinese Clinical Trail Registry, Trial registration number: ChiCTR2000035243, Date of registration: Aug. 5, 2020. URL of trial registry record: http://www.chictr.org.cn/index.aspx

BackgroundCurcumin has multifunctional pharmacological properties, including anti-oxidant, anti-inflammatory, and anti-diabetic properties. We investigated whether curcumin can improve pathological changes associated with Alzheimer's disease, including amyloid β (Aβ), protein kinase B (PKB, also termed Akt), and glycogen synthase kinase 3β (GSK3β) levels and expression. MethodsAlzheimer’s transgenic APPSWE/PS1ΔE9 mice and wild type mice were treated with curcumin by intragastric administration for 2 weeks at 2 and 5 months of age. Aβ plaques and contents in the brain and retina were measured by immunohistochemistry and enzyme-linked immune sorbent assay, respectively, while the expression of Akt and GSK3β was tested by RNA isolation and quantitative real-time poly merase chain reaction. Bloods of patients with AD and age-matched health controls were used to determine the contents of Aβ, Akt and GSK3β. ResultsCurcumin treatment decreased Aβ accumulation in the early stages of AD at 5 months (p < 0.001). It also improved AD-associated pathological changes, including upregulation of Akt (p < 0.01) and downregulation of GSK3β (p < 0.01). In addition to AD-associated changes, the proinflammatory cytokine IL-1β was significantly decreased by curcumin treatment (p < 0.05). ConclusionsCurcumin can suppress Aβ accumulation during the early stages of AD, upregulate the expression of Akt, downregulate the expression of GSK3β, and inhibit the proinflammatory cytokine IL-1β. Curcumin can be used to improve pathological features of AD in the early stages of disease

Background: Retinal biomarkers of Alzheimer’s disease (AD) were largely investigated during last decades. Brain conditions could be reflected by retinal nervous and vascular parameters. It can be used to enhance the accuracy of early diagnosis of AD.Objective: Our study aimed to evaluate the difference of retinal neuro-layer thickness and vascular parameters between AD patients and health control (HC) subjects.Methods: Non-invasive technology of optical coherence tomography angiography (OCTA) were adopted to acquire the combination thickness of retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL), as well as the full retinal thickness (FRT). Vascular branch (VB), vascular curvature (VC), and vascular density (VD) were also collected in AD and HC groups. Mini-mental state examination (MMSE) was adopted to evaluate the cognitive levels of all subjects. After obtaining all the parameters, we used Mann-Whitney U test to compare the mean values of all retinal regions parameters between ADs and HCs. Pearson's correlation was used to test the association between retinal parameters and MMSE score, and vascular parameters.Results: Compared with HCs, the RNFL+GCL thickness of inferior quadrant, FRT of inferior and temporal quadrant, and retinal VD of patients with AD were significantly reduced (p < 0.05). The retinal thickness had significant correlations with MMSE scores (p < 0.05). Meanwhile, the retinal VD was significantly correlated with the average RNFL+GCL thickness (p < 0.05, r = 0.5956).Conclusion: In conclusion, our study suggested that AD patients had significant reduced RNFL+GCL thickness and vascular density compared with the age-matched HCs. Meanwhile, these reductions correlated with the cognitive level of the subjects. Trial registration number: ChiCTR2000035243Date of registration: Aug., 5, 2020URL of trial registry record: http://www.chictr.org.cn/index.aspx