Impaired retinal microcirculation in patients with Alzheimer's disease.

Hong Jiang,Yi Liu,Yingying Shi,Xiaoyan Sun,Yantao Wei,Clinton B Wright,Jonathan Landman,Jianhua Wang,Bernard S Baumel,Tatjana Rundek,Masaki Mogi

doi:10.1371/journal.pone.0192154

Abstract

The goal of this study was to determine the retinal blood flow rate (BFR) and blood flow velocity (BFV) of pre-capillary arterioles and post-capillary venules in patients with mild cognitive impairment (MCI) and Alzheimer’s disease (AD). Forty patients (20 AD and 20 MCI) and 21 cognitively normal (CN) controls with a similar age range (± 5 yrs) were recruited. A retinal function imager (RFI) was used to measure BFRs and BFVs of arterioles and venules in the macular region. The thickness of the ganglion cell-inner plexiform layer (GCIPL) was measured using Zeiss Cirrus optical coherence tomography. Macular BFRs in AD group were 2.64 ± 0.20 nl/s (mean ± standard deviation) in arterioles and 2.23 ± 0.19 nl/s in venules, which were significantly lower than in MCI and CN groups (P < 0.05). In addition, BFRs in MCI were lower than in CN in both arterioles and venules (P < 0.05). The BFV of the arterioles was 3.20 ± 1.07 mm/s in AD patients, which was significantly lower than in CN controls (3.91 ± 0.77 mm/s, P = 0.01). The thicknesses of GCIPL in patients with AD and MCI were significantly lower than in CN controls (P < 0.05). Neither BFV nor BFR in arterioles and venules was related to age, GCIPL thickness, mini mental state examination (MMSE) score and disease duration in patients with AD and MCI (P > 0.05). The lower BFR in both arterioles and venules in AD and MCI patients together with the loss of GCIPL were evident, indicating the impairment of the two components in the neurovascular-hemodynamic system, which may play a role in disease progression.

Highlights

Adequate blood supply is critical to maintain normal brain function
The blood flow velocity (BFV) of the venules were 2.44 ± 0.71 mm/s in Alzheimer’s disease (AD) patients and 2.61 ± 0.61 mm/s in mild cognitive impairment (MCI) patients, which were not significantly different compared to controls (2.79 ± 0.54 mm/s, P > 0.05, Fig 2)
Our study showed that patients with AD and MCI had decreased macular blood flow rate (BFR), which is in agreement with cerebral hypoperfusion previously measured in AD [22,22] and MCI [23]

Summary

Introduction

Adequate blood supply is critical to maintain normal brain function. Altered blood flow leads to neural dysfunction [1]. Cerebral hypoperfusion is evident in patients with Alzheimer’s disease (AD) and in patients with mild cognitive impairment (MCI) determined by various imaging modalities [2]. Impaired retinal microcirculation in AD alter our adherence to PLOS ONE policies on sharing data and materials. The retina and brain have the same embryological origin, and their microvasculature has similar anatomical and physiological features. The retina’s neuronal and vascular changes are similar to changes known to occur in the brain. The retina is accessed by noninvasive optical imaging modalities and is readily studied [3,4]. The loss of retinal nerve fibers and neurons (i.e. ganglion cells), the thinning of the retinal nerve fiber layer (RNFL) and combined ganglion cell and inner plexiform layer (GCIPL) are detected by optical coherence tomography (OCT) and have been reported in patients with AD and MCI [5,6,7,8]

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