Neurocognitive Impact of Long COVID
For many people, long COVID has associations with serious neurological and neurocognitive impairments, a phenomenon sometimes known as neuro-COVID. Why does this happen, and who is most at risk? In this Special Feature and podcast, we speak to two researchers and a person with lived experience of neuro-COVID to find out more.
As the COVID-19 pandemic progresses, there is growing awareness that around 1 in 3 people who tested positive for COVID-19 and who were usually not admitted to the hospital for treatment do not recover fully by 3 months.
An international studyTrusted Source of people with long COVID documented 203 different symptoms across 10 body systems. More than 88% of the 3,762 people who completed the online survey reported memory problems and cognitive dysfunction, making these the “most persistent and pervasive symptoms in this cohort, equally common across all age groups.”
Two-thirds (65%) reported experiencing symptoms for 6 months. Cognitive dysfunction was one of the top three most debilitating symptoms, alongside fatigue and breathlessness.
Brain fog is the most common symptom described by people with cognitive dysfunction following COVID-19 illness. In this feature in the MNT: In Conversation series and associated podcast, Prof. Gabriel de Erausquin and Dr. Lavanya Visvabharathy discuss the latest research and hypotheses regarding long-term cognitive dysfunction after COVID-19.
Long COVID, post-COVID syndrome, or PASC (post-acute sequelae of COVID-19 infection) describe ongoing physical, cognitive, or both symptoms at least 6-12 weeks after having a positive test for COVID-19 or symptoms of acute COVID-19. Neuro-COVID in long-haulers, or long-neuro-COVID, describes the lasting neurological symptoms following acute infection with SARS-CoV-2. Those with neuro COVID usually complain of brain fog — the inability to think as clearly as usual.
The closest we get in medical terms to understand brain fog is that it represents a loss of executive function. It is a symptom that has associations with anxiety, as have many of the respiratory and cardiovascular symptoms of long COVID, such as breathlessness, palpitations, and dizziness. The overlap with psychiatric diagnoses and post-viral fatigue has made it difficult for people with long COVID to obtain a formal cognitive assessment.
However, people who have post-COVID-19 symptoms are eight times more likely to have contracted the virus than people who have not and are three times more likely to have those symptoms consistently over 12 weeks. Dementia is a risk factor for severe COVID-19, increasing the chances of being hospitalized more than three times. Another study from the U.K. Biobank has shown a link between the ApoE e4 genotype, associated with Alzheimer’s disease and severe COVID-19.
A paper presented at the Alzheimer’s Association International Conference (AAIC) 2021 by Prof. M. Wisniewski showed that hospitalized patients with COVID-19 and neurological symptoms were more likely to have serum biomarkers of neuronal injury, neuroinflammation, and Alzheimer’s disease, indicating an acceleration of Alzheimer’s pathology. Moreover, a study whose results appeared in Brain in October 2021 found a further link between the genetic risk for dementia and the risk of developing severe COVID-19.
Namely, a specific variant of the OAS1 gene which influences the riskTrusted Source of Alzheimer’s disease is also tied to an increased risk of severe COVID-19. According to the study authors, this is because a lowered expression of OAS1 in microglia, a type of neural cells found in the brain and spinal cord, is associated with a heightened pro-inflammatory response at cellular level.
At first, we thought that was because people with dementia were less likely to be able to adhere to physical distancing and mask-wearing, or were exposed in their care institutions when there was a mass discharge from hospitals. However, even after adjustment for these risk factors, those with even early dementia were still at a much higher risk.
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Asian Journal of Biomedical & Pharmaceutical Sciences