Brain | Sars Cov2 Health Imp

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Covid-19 Impacts the Brain

Covid-19 Causes Brain Damage

Mild Covid infection shows significant orbitofrontal cortical atrophy (shrinking of parts of the brain) and cognitive decline (Crunfli et al., 2022 doi: 10.1073/pnas.2200960119)

Mild COVID-19 infection can cause impaired neurogenesis (nervous tissue growth), myelin and oligodendrocyte (nerve insulation) loss and increased neurotoxic molecules around the central nervous system (Fernández-Castañeda et al., 2022 *preprint doi: 10.1101/2022.01.07.475453)

MRIs of 401 patients done before and after Covid infection showed reduction in global brain size, grey matter loss (orbitofrontal cortex and parahippocampal gyrus) and cognitive decline. (Douaud et al., 2022 doi: 10.1038/s41586-022-04569-5)

COVID increases the risk of neurodegenerative disorders- Alzheimer’s disease risk is 3.5x increased; Parkinson’s disease risk is 2.6x increased; ischaemic stroke risk is 2.7x increased and intracerebral haemorrhage (bleeding in the brain) risk is 4.8x increased. (Zarifkar et al., 2022 doi: 10.3389/fneur.2022.904796)

Risks of cognitive deficit, dementia, psychotic disorders, and epilepsy or seizures are increased for at least 2 years following Covid infection. (Taquet et al., 2022 doi: 10.1016/S2215-0366(22)00260-7)

In 25% of mild Covid cases, visuocontructive cognitive deficits are seen, associated with changes in brain structure and metabolism. (de Paula et al., 2022 doi: 10.1038/s41380-022-01632-5)

Autopsies of Covid patients, of whom most were not hospitalised at time of death, show vascular leakage, platelet aggregation, neuroinflammation and neuronal injury. (Hwa Lee et al., 2022 doi: 10.1093/brain/awac151)

Covid infection in Non-Human Primates shows evidence of hypoxic-ischaemic injury (damage from lack of oxygen) and neuron degeneration and apoptosis (brain cell loss), including in those who do not develop severe disease. (Rutkai et al., 2022 doi: 10.1038/s41467-022-29440-z)

Loss of smell may be due to damage to the olfactory region of the brain. Covid infection is associated with axon injuries (a part of neuronal cells) and microvasculopathy (damage to small blood vessels) in olfactory tissue, which in some cases could be permenant. (Ho et al., 2022 doi: 10.1001/jamaneurol.2022.0154)

Covid-19 Causes Cognitive Impairment

In a sample of adults over 60, more than 60% showed cognitive decline following Covid infection. Cognitive decline was not related to severity of infection, but was correlated with persistent loss of smell. (Zamponi et al., 2021 - alz.confex.com/alz/2021/meetingapp.cgi/Paper/57897)

A protein produced by Covid is shown to induce cognitive deficit and anxiety-like behaviour in mice. This is accompanied by neuronal cell death in the hippocampus. (Oh et al., 2022 doi: 10.1038/s41598-022-09410-7)

Cognitive dysfunction was 2.2-3x more prevalent in healthcare workers following Covid infection, with implications for quality healthcare delivery. (Carazo et al., 2022 doi: 10.1093/ofid/ofac386)

Hospitalised Covid patients cognitive loss is similar on average to that sustained with 20 years ageing, and equivalent to losing 10 IQ points. (Hampshire et al., 2022 doi: 10.1016/j.eclinm.2021.101044)

People reportedly recovered from Covid show decreased intelligence and significant cognitive deficits. (Hampshire et al., 2021 doi: 10.1016/j.eclinm.2021.101044)

Covid Causes Alzheimer’s-like Pathology and Accelerates Existing Alzheimer’s Disease

• Covid invades cognitive centers of the brain and induces Alzheimer’s-like neuropathology

(Shen et al., 2022 *preprint doi: 10.1101/2022.01.31.478476)

• Covid is associated with accelerated progression of Alzheimer’s disease

(aaic.alz.org/releases_2021/covid-19-cognitive-impact.asp)

• Covid produces proteins that form cytotoxic aggregates which damage neuronal cells, which parallels Alzheimer’s disease mechanism

(Charnley et al., 2022 doi: 10.1038/s41467-022-30932-1)

• COVID increases the risk of neurodegenerative disorders- Alzheimer’s disease risk is 3.5x increased; Parkinson’s disease risk is 2.6x increased; ischaemic stroke risk is 2.7x increased and intracerebral haemorrhage (bleeding in the brain) risk is 4.8x increased.

(Zarifkar et al., 2022 doi: 10.3389/fneur.2022.904796)

• Risks of cognitive deficit, dementia, psychotic disorders, and epilepsy or seizures are increased for at least 2 years following Covid infection.

(Taquet et al., 2022 doi: 10.1016/S2215-0366(22)00260-7)

• A study of hospitalised Covid patients showed neurodegenerative biomarkers elevated to levels seen in Alzheimer’s Disease dementia.

(Frontera et al., 2022 doi: 10.1002/alz.12556)

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