It was found early on that population with respiratory problems is at greater risk but risk factors include pre-existing diagnoses such as dementia, subarachnoid hemorrhage and epilepsy.  Increased risk is found when the acute care uses sedation, ventilation and delirium. 


Ohio State University, Columbus

University of Michigan - Ann Arbor

COVID-19 patients have reported mental fatigue and loss of concentration.  Severe cognitive impairment is reported by people with secondary illnesses.  Encephalopathy (damage to brain) is observed after extubation.  This could be because of sedation or mechanical ventilation.  Damage to the brain can occur from bacteria during ventilation. 
 



Cognitive impacts of COVID-19

Even in the absence of typical respiratory symptoms such as fever, cough, and shortness of breath, various patients diagnosed with COVID-19 have presented neurological symptoms, such as:

- acute cerebrovascular diseases

- impaired consciousness

-  skeletal muscle injury

- encephalopathy (symptoms: ischemic stroke)

- loss of smell (anosmia) and taste (ageusia)

- stroke

- cranial nerve deficits

- delirium

- meningitis

- paralysis

- seizures

- neuroinflammatory syndromes

- high pressure CSF

- muscle stiffness

The list below includes less-common neurological symptoms of COVID-19:
- Guillain–Barré syndrome (GBS)
- Multisystem Inflammatory Syndrome in Children (MIS-C)

Neurological symptoms Presented in COVID-19 Patients

Waterman, K. (2020, May 6). COVID-19 Impact on the Brain and Psyche. Retrieved July 22, 2020, from https://www.nm.org/about-us/northwestern-medicine-newsroom/nm-news-blog/covid-19-impact-on-brain-and-psyche

COVID-19 Impact on the Brain and Psyche

Who is likely to suffer from neurocognitive symptoms

Patients with MS are specifically vulnerable to the neuropsychiatric impacts of the COVID-19 pandemic. About 70% of multiple sclerosis patients suffer from cognitive dysfunction.  This affects information processing and impacts episodic memory. Depression and anxiety result in a lower quality of life, increased fatigue and disability scores, and a more aggressive MS course.  Studies show that depression impacts cognition and anxiety worsens the patient's verbal learning.

Neuropsychiatric and cognitive effects of COVID-19 on multiple sclerosis patients

COVID-19 is directly relevant to the cognitive health of the aging brain in a number of ways, including the effects of the disease, treatments, and current society. cause brain effects such as encephalopathy, similar to the 2002 Severe Acute Respiratory Syndrome, which showed seizures and brain tissue injury. COVID-19 causes respiratory failure, which is linked to increased risk of dementia due to a lack of oxygen to the brain.  Ventilators and sedation causes distress to cognition and causes delirium.  Long-term impaired memory and thinking are observed long after discharge as a result of post-traumatic stress.

A Tsunami of Dementia Could Be on the Way

Most researchers believe the neurological effect of the virus are an indirect result of either oxygen starvation to the brain (the “happy hypoxia” exhibited by many patients), or the byproduct of the body’s inflammatory response (the famed “cytokine storm”).  A pateints MRI brain scan showed signs of viral meningitis (inflammation of the brain), and a lumbar puncture detected Sars-CoV-2 in his cerebrospinal fluid.  Another patient had viral particals detected in the  endothelial cells lining the blood vessels of the brain itself. In fact, some scientists now suspect that the virus causes respiratory failure and death not through damage to the lungs but through damage to the brainstem.

How COVID-19 can damage the brain

cognition isn't just about thinking but also about brain function.  Many patients have experienced loss of smell, delirium and an increased risk of stroke.  Many experience long lasting effects of the brain.  Some topics to focus on would be as follows:
-  The immune system and the brain
-  How does inflammation exert long-lasting effects on memory?
-  Does COVID-19 increase risk for cognitive decline?

How COVID-19 might increase risk of memory loss and cognitive decline

Mao et.al study finds that 36.4% of the COVID-19 patients surveyed presented neurologic symptoms, such as acute cerebrovascular events, impaired consciousness and skeletal muscle injury. Neurologists conducted a study (Jan. 16 - Feb. 19) (n=214, from 3 designated Wuhan hospitals) by retrospectively reviewing patient charts. Nervous system symptoms were found to be more prevalent in severe patients, affecting them disproportionately to their counterparts with regards to CNS function and muscle injury.

Increased neurologic symptoms in severely infected COVID-19 patients

- Encephalopathy (overall)
- Ischemic Stroke
- Multisystem Inflammatory Syndrome in Children (MIS-C)
- Induce brain and spine demyelinating lesions
- Mast cell activation
- Acute cerebrovascular disease 
- Intracranial hemorrhage
- Seizure (caused by meningitis)
- Neuroinflammatory syndromes 
- Post-infection cerebral changes

COVID-19 Reports on Patient Neurological Symptoms, Organized by Symptoms Affecting the CNS

- Multisystem Inflammatory Syndrome in Children (MIS-C)
- Guillain-Barré Syndrome
- Loss of smell (hyposmia/anosmia) and taste (hypogeusia/ageusia)
- Serious damage to cranial nerves, peripheral nerves, and muscles


COVID-19 Reports on Patient Neurological Symptoms, Organized by Symptoms Affecting the PNS

Up to 20% of COVID-19 patients who enter the intensive care unit (ICU) with neurological issues or deficits have a higher mortality risk. Even after recovering and leaving the ICU, patients may develop long-term neurological conditions such as depression, obsessive compulsive disorder, psychosis, Parkinson’s disease, and Alzheimer’s disease. ICU patients who take numerous medications or have pre-existing medical conditions can develop memory loss, slow processing speed, delirium, or even coma. Patients with multiple sclerosis, amyotrophic lateral sclerosis, and respiratory dysfunction may struggle to survive ICU hospitalization, and those on immunosuppressive medications may decline faster.


Effects of ICU Admission on COVID Patients with Neurological Issues

Effects on the nose, cranial nerves and brain
1) Anosmia and ageusia caused by inhibition of nasal and gustatory epithelial cells
2) Vessel occlusion in cerebral arteries caused by activation of cytokines and hypercoagulation pathways in the blood
3) Blood clots in the cerebral veins leading to cerebral venous thrombosis.
4) Seizures and/or encephalopathy from high levels of cytokines in the cerebral vessels damaging the blood-brain barrier, infiltrating the brain, and damaging neurons and glia 
5) Meningitis from artery damage
6) Cranial nerve damage from formation of auto-antibodies (molecular mimicry)

Figure 2. Pathophysiology of Neurological Abnormalities in COVID-19

- Stage I: anosmia, ageusia

- Stage II: blood clots, PNS damage

-Stage II: seizures, coma, encephalopathy


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