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Review
. 2022 Nov 4:10:e14227.
doi: 10.7717/peerj.14227. eCollection 2022.

Role of neuroinflammation mediated potential alterations in adult neurogenesis as a factor for neuropsychiatric symptoms in Post-Acute COVID-19 syndrome-A narrative review

Jayakumar Saikarthik #  1   2 , Ilango Saraswathi #  3 , Abdulaziz Alarifi  4   5 , Abdulrahman A Al-Atram  6 , Suresh Mickeymaray  7 , Anand Paramasivam  8 , Saleem Shaikh  2   9 , Mathew Jeraud  10 , Abdulaziz S Alothaim  7
Affiliations
Review

Role of neuroinflammation mediated potential alterations in adult neurogenesis as a factor for neuropsychiatric symptoms in Post-Acute COVID-19 syndrome-A narrative review

Jayakumar Saikarthik et al. PeerJ. .

Abstract

Persistence of symptoms beyond the initial 3 to 4 weeks after infection is defined as post-acute COVID-19 syndrome (PACS). A wide range of neuropsychiatric symptoms like anxiety, depression, post-traumatic stress disorder, sleep disorders and cognitive disturbances have been observed in PACS. The review was conducted based on PRISMA-S guidelines for literature search strategy for systematic reviews. A cytokine storm in COVID-19 may cause a breach in the blood brain barrier leading to cytokine and SARS-CoV-2 entry into the brain. This triggers an immune response in the brain by activating microglia, astrocytes, and other immune cells leading to neuroinflammation. Various inflammatory biomarkers like inflammatory cytokines, chemokines, acute phase proteins and adhesion molecules have been implicated in psychiatric disorders and play a major role in the precipitation of neuropsychiatric symptoms. Impaired adult neurogenesis has been linked with a variety of disorders like depression, anxiety, cognitive decline, and dementia. Persistence of neuroinflammation was observed in COVID-19 survivors 3 months after recovery. Chronic neuroinflammation alters adult neurogenesis with pro-inflammatory cytokines supressing anti-inflammatory cytokines and chemokines favouring adult neurogenesis. Based on the prevalence of neuropsychiatric symptoms/disorders in PACS, there is more possibility for a potential impairment in adult neurogenesis in COVID-19 survivors. This narrative review aims to discuss the various neuroinflammatory processes during PACS and its effect on adult neurogenesis.

Keywords: Astrocyte; COVID-19; Cytokine storm; Microglia; Neurogenesis; Neuroinflammation; Post-acute COVID-19 syndrome; SARS-CoV-2.

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Conflict of interest statement

Jayakumar Saikarthik is an Academic Editor for PeerJ.

Figures

Figure 1
Figure 1. Proposed routes of entry of SARS-CoV-2 into the central nervous system.
Figure 2
Figure 2. Adult neurogenesis in the dentate gyrus of hippocampus.
NSC, neural stem cell; NB, neuroblast; IN, immature neuron; MN, mature neuron; CA1 and CA3, Cornu Ammonis 1 and 3 regions.
Figure 3
Figure 3. Putative mechanism depicting the effect of neuroinflammation on adult neurogenesis during PACS.
The entry of SARS-COV-2 virus into the brain triggers the release of proinflammatory cytokines which may potentially affect the hippocampal neurogenesis. This could be possibly hypothesized as the reason for the various neuropsychiatric symptoms that are present during PACS.
See this image and copyright information in PMC

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