How COVID-19 affects the brain

A 2020 study in The Lancet Psychiatry of almost 240,000 people with COVID-19 reported they had a little more than 2% rate of ischemic stroke. A subgroup of almost 9,000 people who were admitted to the intensive care unit had an almost 7% risk of ischemic stroke. In the same study, the rate of intracranial hemorrhage in those with COVID-19 was almost 1%, and the rate among those in the ICU was almost 3%. A small study in China reported that age, a history of diabetes or hypertension, severe COVID-19, and a significant inflammatory or coagulation response increased the risk of stroke in COVID-19 patients.

A 2020 study that appeared in The Lancet Psychiatry reported that people diagnosed with COVID-19 had a more than 17% rate of anxiety disorder, and the rate among those admitted to the ICU with COVID-19 was greater than 19%. The researchers said the rate of psychiatric disorders such as mood and anxiety disorders was not as strongly associated with the severity of COVID-19 compared to the rate of neurological disorders, such as encephalopathy and stroke. This finding suggests anxiety disorder may reflect the psychological impact of a COVID-19 diagnosis, rather than being caused by the condition.

A review of 2020 research published in the international journal Acta Neurologica Belgica also found a relationship between COVID-19 and the onset of depressive conditions, especially in patients with severe cases of the virus.

The findings of The Lancet Psychiatry study support previous evidence of an association between COVID-19 and dementia. The more recent study reported that almost 3% of those over 65 had a first diagnosis of dementia six months after their COVID-19 diagnosis. Almost 5% of those with encephalopathy had a first diagnosis of dementia six months after diagnosis.

People with a history of severe respiratory distress and hypertension have an increased risk of developing encephalopathy as the first symptom of COVID-19. The risk increases with the severity of the infection. COVID-19-associated encephalopathy may have multiple causes, including metabolic factors; medication; and hypoxia, or insufficient oxygen. The symptoms of encephalopathy are treated with anticonvulsant medication; antipyretic, or fever-reducing medication; and high-flow nasal cannula support for oxygen therapy.

Encephalitis, or inflammation of the brain, is a type of encephalopathy that is caused by an infection, including a viral infection. Symptoms of encephalitis include fever, headache, and delirium. Patients with COVID-19 may also have seizures. Those with COVID-19 may present with encephalitis rather than respiratory symptoms, although it is rare. A July 2020 study published in the journal Brain, Behavior, and Immunity suggests a link between COVID-19 and encephalitis.  

A study of patients with COVID-19 reported that 44% to 70% of those hospitalized had myalgia and fatigue. Unfortunately, the rapid spread of the novel coronavirus prevented a thorough workup of COVID-19 patients that may have helped doctors determine how the infection caused these symptoms. Myalgia correlates with increased creatinine kinase level and lymphocyte count, which suggests COVID-19 may cause muscle damage and could interfere with muscle energy production, according to a study published in March 2021 by the International Journal of Clinical Practice.