While the COVID-19 virus (SARS-CoV-2) public health emergency declaration officially ended this month, on May 11th, the infectious disease has not gone away. Experts say COVID is here to stay. That is especially true for those dealing with the long-term effects of COVID.
COVID’s Neurologic Symptoms
At initial infection, most people infected with COVID-19 have some neurologic symptoms. The most common neurologic symptom is headache; one-half of patients who have COVID-19 present with headaches. Other associated symptoms include muscle aches, anosmia (impaired sense of smell), and ageusia (impaired sense of taste). Some people with COVID experience more profound effects on the nervous system. Although rare, neurologic events can include stroke, altered consciousness, coma, and encephalopathy (diffuse impaired brain functioning).
Many people continue to suffer from a wide range of long-lasting COVID symptoms. Dubbed “Long COVID,” the most persistent and disabling symptoms of Long COVID are neurological. Long COVID’s most common neurologic symptoms include pain, fatigue, and “brain fog,” characterized by difficulty concentrating and impaired memory.
According to a Scientific American article, Long COVID was estimated to affect more than 15 million American adults by early 2023. In addition, a 2022 study found that as many as four million Americans were forced out of the workforce due to COVID. These numbers are generally accepted to be accurate, but more dire assessments exist. For example, a 2021 meta-analysis of 41 studies concluded that 30 percent of Americans infected with SARS-CoV-2 are at risk of developing Long COVID – translating into about 30 million people.
Who Gets Long COVID
The profile of Long COVID is surprisingly varied. While Long COVID is more severe and occurs more often following severe infections with hospitalizations and those ages 65+, it also affects healthy, younger adults and those who only presented initially with mild cases. The characteristics of those at higher risk include:
- Those in lower socioeconomic classes
- Obese people and
- Those with other medical conditions, significantly impaired immune systems, or autoimmune diseases.
While vaccinations undoubtedly reduce becoming infected, they have a much smaller benefit in preventing Long COVID, according to a 2022 study published in Nature Medicine. This study of more than 13 million people found that vaccination lowers the risk of Long COVID after infection by only 15%.
The Neurologic Symptoms Associated with Long COVID
The most recognizable brain or nerve-related neurologic Long COVID symptoms include impairment in memory, attention, sleep, and mood. Other symptoms related to the nervous system include post-exertional malaise, which is experienced as profound fatigue after even mild exercise.
These symptoms arise from disturbances of the autonomic system (called dysautonomia), comprised of a network of nerves stemming from the brain or spinal cord and networking throughout the body. The autonomic nervous system controls bodily functions such as breathing, heart rate, sweating, blood vessel dilation, and digestion. Dysautonomia can cause dizziness, a fast heartbeat, and high and low fluctuations in blood pressure. One disorder from dysautonomia associated with Long COVID has been called Postural Orthostatic Tachycardia Syndrome or POTS. POTS is experienced as a racing heart rate on standing, profound fatigue, and bowel and bladder dysfunction. While this may not initially be obvious, these symptoms stem from neurologic dysfunction.
How Coronaviruses Affect Neurons
Numerous coronaviruses affect both humans and animals. While most are associated with respiratory symptoms, three have been shown to infect neurons – specifically, HCoV-22, HCoV-OC43, and SARS-CoV-1. In addition, several types of brain cells found in the brain are infected along with neurons in HCoV-OC43 infections (Oligodendrocytes, astrocytes, microglia, and neurons), most of which support persistent infection.
Viruses use spike proteins on the viral surface to bind to an angiotensin-converting enzyme 2 (ACE2) receptor. The presence of this receptor on tissues throughout the body determines how vulnerable that tissue is to viral infection. ACE2 is also found throughout the brain. ACE2’s presence in the brain raises concern that SARS-2 CoV-2, like the previously studied SARS-CoV-1, can infect nervous system cells throughout the central nervous system.
Here’s how the possible route of the SARS-CoV-2 infection to the brain: the infection enters through the olfactory nerve (which controls the sense of smell), through the lining of blood vessels, or through migration of infected white cells (immune cells) across the blood-brain barrier.
Long COVID and Multiple Sclerosis
Further, studies have shown that, based on RNA evaluation and CSF (Cerebrospinal fluid) analysis, a history of infection with HCoV-OC43 is associated with multiple sclerosis. (Source 1 and 2). In other words, coronaviruses can infect the central nervous system and raise the possibility that these viruses contribute to demyelination in some patients. (Our blog here explains how MS is caused by an abnormal immune response to attack and damage the myelin, the coating of the nerve cells in the brain and spinal cord, to cause demyelination).
The hypothesis is that this potential for demyelination may result from an adaptive (appropriate) immune response. Antibodies are produced to target the virus proteins on the HCoV-OC43 virus. These antibodies cross-react with myelin antigens – resulting in demyelination. In other words, the antibodies are doing their job and the unintended side effect of damage to the myelin results.
Recommendations for MS Patients
While the association of developing MS from a SARS-CoV2 infection has not been made, patients with MS who take immunosuppressant therapies are at greater risk of more severe COVID-19. In response to this risk, in April 2020, the National MS Society published recommendations for all patients with MS to continue disease-modifying therapies. In addition, the organization suggested that physicians treating MS patients with immunosuppressants consider switching patients to non-immunosuppressant MS therapies such as interferons, glatiramer acetate, or natalizumab.
Further complicating the picture for MS patients is that some COVID-19 and Long COVID symptoms may overlap with non-COVID-related MS symptoms. The bottom line is that MS patients need to communicate the timing and nature of their symptoms to their treating physicians to make appropriate clinical decisions. More research is required.
Dealing with multiple sclerosis or Long COVID is an everyday struggle. Taking a proactive role in one’s healthcare is critical to monitoring and managing the disease between doctors’ appointments. BeCare MS Link can help. Our app can monitor for changes in neurologic function after a COVID infection and for MS patients. As a result, patients, along with their clinicians, can help guide the therapy that’s best for them.