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Long COVID and neurological effect

COVID-19 as an infectious disease caused by a newly discovered coronavirus, SARS-CoV-2 has become a global pandemic since December, 2019. Since then, medical understanding of COVID-19 has continued to evolve, including disease transmission, pathophysiology, clinical manifestations, treatment and disease prevention as well as various types of vaccines protecting against COVID-19 infections. Patients with COVID-19 often fully recover within a few weeks. Nonetheless, some people continue experiencing certain symptoms after their initial recovery. These people are referred to long haulers and the conditions have been described as “long COVID” or post-COVID-19 syndrome. Among other systems and organs in the body, accumulating evidence indicates that patients with long COVID commonly develop neurological symptoms after the acute illnesses have resolved.


Get to know long COVID

Similar to other respiratory tract infections, common signs and symptoms of COVID-19 are fever, cough, runny nose, sore throat, headache, dizziness and difficulty breathing. In fact, loss of smell or taste appears to be a unique feature of COVID-19. However, patients with COVID-19 might experience a wide variety of manifestations, hinging upon disease severity and their pre-existing health conditions.

After recovery from an initial illness caused by COVID-19, some people continue experiencing a wide range of signs and symptoms, affecting different organs in the body.  These people are referred to long haulers and the conditions have been described as long COVID or post-acute COVID syndrome. The incidence of a long-COVID feature widely varies among different studies conducted in several countries across the world, ranging from 32% to 96% in the 90-day period after confirmed infections. The findings derived from the recent meta-analysis among 10,000 COVID-19 patients reveal that after 60 days of acute COVID-19 infections, 73% of these patients develop long-term symptoms after their initial illnesses have resolved, defined by negative result on the SARS-CoV-2 RT-PCR test.

Long COVID and multiple system involvement

Long COVID is a term used to describe the effects of COVID-19 that persist for 4 weeks or longer beyond the initial illness. Long COVID results in a broad range of manifestations, affecting different organs and systems in the body, including:

  • Respiratory system: breathing difficulties e.g. shortness of breath and feeling tired.   
  • Cardiovascular system: palpitation, chest pain or tightness and rapid heartbeat.   
  • Gastrointestinal system: abdominal pain, diarrhea and loss of appetite.
  • Non-specific symptoms: body or muscle ache, joint pain, weakness and fatigue. 
  • Abnormal laboratory results without any signs or symptoms:  elevated liver enzymes, impaired kidney function with decreased glomerular filtration rate, abnormal levels of thyroid hormones, unusual blood clotting and disruption of glycometabolic control in diabetic patients.

Long COVID and neurological effects

Prolonged multisystem involvement has been reported among patients with long COVID. Neurological and psychological symptoms often caused by long COVID are as follows:

  • Headache
  • Vertigo or dizziness
  • Insomnia
  • Delirium
  • Post Traumatic Stress Disorder: PTSD
  • Depression
  • Obsessive compulsive disorder and anxiety
  • Brain fog: Brain fog is often described as a cloudy-headed feeling.  It is considered a lingering problem affecting the ability to perform daily tasks, including feeling spacy or confused, thinking or making decision more slowly than usual, being easily distracted with impaired concentration, having trouble organizing thoughts or activities. Some patients might experience short-term memory loss, such as forgetting daily tasks or losing a train of thought.
  • Autonomic dysfunction: Autonomic dysfunction is increasingly recognized as an important feature of Long-COVID, with multiple case series describing patients presenting with these two common conditions:
  1. Postural Orthostatic Tachycardia Syndrome or POTS: signs and symptoms include rapid increase in heartbeat that appears when standing up from a reclining position and relieved by sitting or lying back down. POTS can also induce palpitation, chest pain, difficulty breathing, lightheadedness and even fainting.    
  2. Myalgia Encephalitis/Chronic Fatigue Syndrome or ME/CFS: Common manifestations are severe weakness, joint and muscle pain, sore throat, headache, dizziness, vertigo, impaired cognitive function and lack of attention as well as sleep deprivation.   

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Causes of long COVID

Despite the exact cause of long COVID remains unknown, the predominant explanations involve: 

  1. SARS-CoV-2 viruses directly infect cells, causing damages to multiple organs in the body. 
  2. Viral infection activates the immune system to produce inflammatory responses by releasing various substances, known as inflammatory mediators including autoantibodies to fight against the viruses. These immune responses can excessively attack the rest of the body, leading to multiple organ damages.
  3. Long-term sequelae of post-critical illness. During acute COVID-19, microvascular injuries and electrolyte imbalance can potentially induce prolonged symptoms, affecting several organs in the body following a critical illness.

Statistic reports point out that women are more prone to long COVID than men. Other factors contributing to long COVID are being aged 35-49, and having chronic respiratory diseases, such as asthma.  The condition seems more likely in patients who have developed severe forms of COVID-19 and who have experienced a wide range of symptoms involving multiple systems. Nevertheless, due to limited number of COVID-19 patients obtained from recent clinical researches, definite risk factors for developing long COVID have not been firmly established. Once clinical studies in the future can be conducted in a larger number of COVID-19 patients across the world, a conclusion on predominant factors contributing to long COVID should be further attained.

Long COVID and pre-existing neurological conditions

In regard to current medical studies, neurological diseases, such as stroke, dementia and Parkinson’s disease as pre-existing conditions are not associated with the development of long COVID. However, if patients with these neurological conditions become infected with COVID-19, they are at greater risk for disease progression and worsening symptoms, compared to those without COVID-19 infections. More importantly, in comparison to respiratory infections caused by other pathogens, COVID-19 caused by SARS-CoV-2 is more likely to cause neurological complications or provoke pre-existing conditions. Clinical findings reveal that, compared to flu or other viral respiratory infections, patients infected with SARS-CoV-2 significantly pose a greater risk to develop cerebrovascular diseases (e.g. acute ischemic stroke and intracerebral hemorrhage), dementia and psychological issues (e.g. depression and anxiety). Moreover, the risks for developing neurological conditions increase in COVID-19 patients who require hospitalization or intensive care as well as those presenting with delirium while hospitalized.

Regardless of the presence of neurological diseases as underlying conditions, COVID-19 can result in different degrees of damages to multiple systems in the body. Without any underlying diseases, some patients may have certain risks for developing post-COVID effects whereas COVID-19 patients with pre-existing conditions are placed at higher risk to experience disease progression with exacerbation of their underlying diseases. Although having pre-existing neurological conditions are not associated with an increased risk of long COVID, worsening condition and disease aggravation arisen during acute illness often result in serious complications which largely disrupt patient’s quality of life in the long run.

A rare but serious condition associated with long COVID

Multisystem inflammatory syndrome in children (MIS-C) is a rare condition affecting children (aged below 21) where different body parts can become inflamed. Clinical manifestations of MIS-C are considerably similar to those with long COVID. MIS-C symptoms appear between two and eight weeks after COVID-19 infection.

In September, 2021, there was a systematic review on Clinical Characteristics of Multisystem Inflammatory Syndrome in Adults or MIS-A, indicating that some adult patients also experience multisystem inflammatory syndrome in the postacute COVID-19 period owing to a dysregulated immune response. A broad spectrum of symptoms ranges from nausea, diarrhea, abdominal pain, loss of appetite, headache, palpitation, breathing problems and rapid heartbeat. Abnormal results from laboratory tests also include low platelet count, an incremental rise in inflammatory proteins and cardiac inflammatory markers.

Treatment of long COVID

There is no definitive treatment for long COVID, despite certain antiviral drugs have been used during COVID-19 infections. Symptomatic treatments for long COVID are determined by individual’s clinical manifestations and other underlying diseases. To stay healthy, it is highly recommended to exercise regularly and get enough of sleep. Moreover, it remains crucial to notice any unusual signs and symptoms after initial recovery from COVID-19. In case that any abnormality exhibits, immediate medical attention must be sought, allowing effective and timely treatments.