Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2022 May 6:14:888946.
doi: 10.3389/fnagi.2022.888946. eCollection 2022.

Association of Peripheral Blood Cell Profile With Alzheimer's Disease: A Meta-Analysis

Le-Tian Huang  1 , Cheng-Pu Zhang  2 , Yi-Bing Wang  3 , Jia-He Wang  2
Affiliations

Association of Peripheral Blood Cell Profile With Alzheimer's Disease: A Meta-Analysis

Le-Tian Huang et al. Front Aging Neurosci. .

Abstract

Background: Inflammation and immune dysfunction play significant roles in the pathogenesis of Alzheimer's disease (AD)-related dementia. Changes in peripheral blood cell profiles are a common manifestation of inflammation and immune dysfunction and have been reported in patients with AD or mild cognitive impairment (MCI). We systematically evaluated the association of peripheral blood cell counts and indices with AD or MCI through a meta-analysis.

Methods: We electronically searched sources to identify all case-control trials comparing peripheral blood cell counts and/or lymphocyte subsets between patients with AD or MCI and healthy controls (HCs). Meta-analyses were used to estimate the between-group standardized mean difference (SMD) and 95% confidence interval (CI).

Results: A total of 36 studies involving 2,339 AD patients, 608 MCI patients, and 8,352 HCs were included. AD patients had significantly decreased lymphocyte counts (SMD -0.345, 95% CI [-0.545, -0.146], P = 0.001) and significantly increased leukocyte counts (0.140 [0.039, 0.241], P = 0.006), neutrophil counts (0.309 [0.185, 0.434], P = 0.01), and neutrophil-lymphocyte ratio (NLR) (0.644 [0.310, 0.978], P < 0.001) compared to HCs. Similarly, significantly increased leukocyte counts (0.392 [0.206, 0.579], P < 0.001), NLR (0.579 [0.310, 0.847], P < 0.001), and neutrophil counts (0.248 [0.121, 0.376], P < 0.001) were found in MCI patients compared with HCs. A significantly decreased percentage of B lymphocytes (-1.511 [-2.775, -0.248], P = 0.019) and CD8+ T cells (-0.760 [-1.460, -0.061], P = 0.033) and a significantly increased CD4/CD8 ratio (0.615 [0.074, 1.156], P = 0.026) were observed in AD patients compared to HCs. Furthermore, significant changes in hemoglobin level and platelet distribution width were found in patients with AD or MCI compared with HCs. However, no significant difference was found between AD or MCI patients and HCs in terms of platelet counts, mean corpuscular volume, red cell distribution width, mean platelet volume, and CD4+ T, CD3+ T, or natural killer cell counts.

Conclusion: Changes in peripheral blood cell profiles, particularly involving leukocyte, lymphocyte, neutrophil, and CD8+ T cell counts, as well as the NLR and the CD4/CD8 ratio, are closely associated with AD. The diagnostic relevance of these profiles should be investigated in future.

Keywords: Alzheimer's disease; lymphocyte subsets; meta-analysis; mild cognitive impairment; peripheral blood.

PubMed Disclaimer

Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

Figure 1
Figure 1
Overview of literature search and selection.
Figure 2
Figure 2
Forest plots of standardized mean differences (SMDs) for leucocyte counts in Alzheimer's disease (AD) (A) and mild cognitive impairment (MCI) (B), neutrophil counts in AD (C) and MCI (D), compared to healthy controls (HCs).
Figure 3
Figure 3
Forest plots of standardized mean differences (SMDs) for the neutrophil–lymphocyte ratio (NLR) in Alzheimer's disease (AD) (A) and mild cognitive impairment (MCI) (B), and lymphocyte counts in AD (C) and MCI (D), compared to healthy controls (HCs).
Figure 4
Figure 4
Forest plots of standardized mean differences (SMDs) for percentage of CD4+ T cells (A) and CD8+ T cells (B), the CD4/CD8 ratio (C), and percentage of B lymphocytes (D) in Alzheimer's disease (AD), compared to healthy control (HCs).
Figure 5
Figure 5
Forest plots of standardized mean differences (SMDs) for hemoglobin level (A), platelet count (B), and platelet distribution width (PDW) (C) in Alzheimer's disease (AD) compared to healthy controls (HCs).
See this image and copyright information in PMC

References

    1. Alzheimer's Association (2021). 2021 Alzheimer's disease facts and figures. Alzheimer. Dement. 17, 327–406. 10.1002/alz.12328 - DOI - PubMed
    1. An P., Zhou X., Du Y., Zhao J., Song A., Liu H., et al. . (2019). Association of neutrophil-lymphocyte ratio with mild cognitive impairment in elderly Chinese adults: a case-control study. Curr. Alzheimer Res. 16, 1309–1315. 10.2174/1567205017666200103110521 - DOI - PubMed
    1. Araga S., Kagimoto H., Funamoto K., Takahashi K. (1990). Lymphocyte proliferation and subpopulations in dementia of the Alzheimer type. Jpn. J. Med. 29, 572–575. 10.2169/internalmedicine1962.29.572 - DOI - PubMed
    1. Armanini D., Vecchio F., Basso A., Milone F. F., Simoncini M., Fiore C., et al. . (2003). Alzheimer's disease: pathophysiological implications of measurement of plasma cortisol, plasma dehydroepiandrosterone sulfate, and lymphocytic corticosteroid receptors. Endocrine 22, 113–118. 10.1385/ENDO:22:2:113 - DOI - PubMed
    1. Babiloni C., Del Percio C., Lizio R., Infarinato F., Blin O., Bartres-Faz D., et al. . (2014). A review of the effects of hypoxia, sleep deprivation and transcranial magnetic stimulation on EEG activity in humans: challenges for drug discovery for Alzheimer's disease. Curr. Alzheimer Res. 11, 501–518. 10.2174/1567205011666140317095623 - DOI - PubMed

Publication types