COVID-19 and Neurocognitive Disorders

Abstract and Introduction

Abstract

Purpose of Review: The COVID-19 infection results in various viral-related physical and mental health problems, joined with the long-term psychological impact of the pandemic in general. However, the accompanying neurocognitive changes remain poorly understood.

Recent Findings: We synthetize the current knowledge of viral (SARS-CoV-2) induced inflammation, mechanisms to viral entry into the central nervous system and altered neurotransmitter systems to provide an informed neurobiological explanation for the rise of neurocognitive disorders (defined as per the DSM-5 criteria).

Summary: The mild and major neurocognitive disorder symptoms due to the COVID-19 pandemic provide a unique opportunity to address the early changes underlying neurocognitive impairment at both clinical and molecular level. We discuss the utilization of the available evidence for their management and future novel therapeutic opportunities.

Introduction

The COVID-19 pandemic has affected all segments of the world population and has proven detrimental especially to the most vulnerable groups in society. It has gravely impacted those living in poverty, that is homeless people, people unable to secure adequate shelter, refugees, migrants, displaced persons, as well as older people with disabilities or underlying health conditions. Young and indigenous people also stand to suffer disproportionately both from the pandemic as such and from its indirect effects. Importantly, many people with lower socioeconomic status already have health problems (e.g. higher rates of chronic illness, compromised immune systems and so on), which constitute important risk factors for developing a more serious manifestation of the COVID-19 infection.

The record levels of unemployment due to lockdown measures implemented to curb virus transmission, social isolation and limits on nonessential travel outside the home, closure of shops and entertainment venues, bans on mass gatherings (i.e. sports and art events) and remote working have cumulatively contributed to psychological distress, promoting a myriad of 'problem behaviours' such as increased alcohol use, excess smoking, physical inactivity, as well as associated physical problems (i.e. back pain through poor ergonomic posture, scaled-back access to health services and so on).

Table 1. Causes and risk factors for neurocognitive disorders
Cause	Symptoms, mental health and physical conditions as risk factors for neurocognitive disorder
Societal experiences of living in and with COVID-19 pandemic	Social isolation Nutrition Access to healthcare Stress Intense grief reactions Anxiety OCD Alcohol and drug abuse Autoimmune diseases (RA, T1DM)
Respiratory COVID-19 (respiratory failure or laboratory biomarkers showing inflammation or organ damage)	Hypoxia PTSD Anxiety Depression Physical disability Delirium
CNS COVID-19	Encephalitis Stroke Delirium
Previous Dementia Diagnosis/Down syndrome	Increase in psychological symptoms (communication/mood: apathy, anxiety) Increase in behavioural problems (agitation, compliance with new measures) Altered routine daily activity (i.e. movement, physical inactivity) Faster cognitive decline Caregiver burden (psychological and physical, esp. in rural areas Delirium

CNS, central nervous system; OCD, obsessive compulsive disorder; PTSD, post-traumatic stress disorder; RA, rheumatoid arthritis; T1DM, type 1 diabetes mellitus.