A new study reports that brain function can be impaired for 18 months after a person has recovered from COVID-19, especially if the individual was hospitalized. However, COVID-induced cognitive impairment is no more severe than impairment due to other diseases causing hospitalization.
The prospective cohort study, published in JAMA Network Open, suggests that the brain health of COVID-19 patients who were ill enough to go to the hospital suffered long-lasting neurological damage that included new psychiatric diagnoses, such as anxiety and depression, fatigue, and sleep issues. Previous studies showed these symptoms occurred among 12 percent to 50 percent of individuals one year after infection. Consistent with these findings, this study found that about 38 percent of study participants still had cognitive symptoms at the 18-month follow-up.
The results offer insight into long-COVID symptoms and how the virus can affect the brain over time. Although fewer people are being hospitalized for COVID-19, just over 20,000 Americans were hospitalized for the virus during the last week of December.
Disease Severity, Not Necessarily Type, May Influence Cognitive Impairment
Researchers looked at 120 patients hospitalized with COVID-19 at two hospitals in Copenhagen between March 2020 and March 2021. The average patient was 61 years old, and over half of patients (58 percent) were men. The COVID patients were compared to a control group of hospitalized patients, which included 50 who had non-COVID pneumonia, 50 with myocardial infarction, and 25 in non-COVID-related intensive care.
Both the COVID patient group and the control group were assessed for cognitive impairment, underwent psychiatric interviews and neurological examinations, and were assessed for fatigue after they were released from the hospital.
When comparing the COVID group with the non-COVID hospitalized control group, the research team found both groups fared similarly in cognitive, psychiatric, and neurological tests 18 months after they left the hospital. However, the COVID group was worse off in overall executive function and sense of smell. Older patients with COVID-19 had a higher risk of cognitive impairment than healthy controls, the research team noted. COVID patients also experienced more psychiatric issues, sleep issues, and problems involving memory between the six-month and 18-month follow-up periods.
Despite COVID patients understandably experiencing more cognitive issues than healthy controls, those hospitalized both for COVID and non-COVID illnesses showed comparable cognitive impairment, leading researchers to theorize that cognitive impairment is determined more by illness severity and hospitalization than COVID-19.
The new study adds to a growing body of evidence that COVID-19 contributes to cognitive decline, including diminished memory and attention and sleep disturbances. A study conducted by Harvard Medical School in April 2022 noted that patients hospitalized with COVID-19 had such trouble recalling words and paying attention that their cognitive decline equated to losing 10 IQ points. Patients who had to be intubated on ventilators experienced more brain fog, the study found.
COVID-19 Impacts Vital Brain Regions
According to a July 2023 article published in Frontiers in Neurology, scientists believe the SARS-CoV-2 virus damages vital brain regions such as the hippocampus and anterior cingulate cortex. These parts of the brain are responsible for learning and memory, as well as other fundamental cognitive processes like decision-making, learning, and cost-benefit analysis.
How the virus damages the brain is still being studied. The Frontiers in Neurology article hypothesizes that COVID-19 creates neuroinflammation, disrupting neural circuits and connections; in other words, the virus short-circuits parts of the brain, especially the sympathetic nervous system, responsible for reacting to stress. A short-circuited sympathetic nervous system, combined with damaged cognitive function, can leave the brain vulnerable, according to researchers.
Understanding the mechanisms of how COVID-19 affects the brain can help doctors and physicians better treat those who suffer from long COVID, defined as experiencing COVID symptoms at least four weeks after initial infection, according to the U.S. Centers for Disease Control and Prevention (CDC). Symptoms of long COVID often involve myriad mental health and brain-related issues, including tiredness or fatigue that interferes with daily life, depression, change in smell or taste, headache, and difficulty thinking or concentrating—sometimes called brain fog.
