About two-thirds of people hospitalized with a COVID-19 infection experience neurological complications, including loss of smell or taste, brain fog, and headache. Yet prior research studying SARS-CoV-2 (the virus that causes COVID-19 illness) on the brain has used PET scans or other imaging tools, but these images often show conflicting results.
The current review analyzed molecular imaging studies in neuropsychiatric COVID-19 cases. The five symptoms under study involved encephalitis, Parkinson’s disease, and other neurodegenerative diseases, focal symptoms/lesions, encephalopathy, and long COVID. Narrowing the symptoms allowed researchers to understand the diverse and underlying causes behind the symptoms as well as unravel the discrepancies in imaging studies.
“These need to be prospective, recruit larger patient cohorts, follow accepted syndrome or stage definitions, and use proper methodology,” says study co-author, Dr. Jonas A. Hosp, in a statement. Hosp is an attending physician of the Department of Neurology and Clinical Neuroscience at the Medical Center–University of Freiburg in Germany.
“Carefully designed studies of COVID-19 populations will be of great interest moving forward,” he adds.
People who reported multiple neurological complications such as fatigue, memory problems, and loss of taste or smell were more likely to experience limbic and subcortical hypometabolism — a decrease in brain glucose consumption and a major sign in neurodegenerative diseases. However, other studies using PET scans reported no changes in brain metabolism when patients reported minor cognitive impairments. Interestingly, none of the studies reviewed by researchers showed irreversible brain damage.
“To the best of our knowledge there are no convincing studies clearly demonstrating relevant and irreversible brain damage, except for disease complications like brain infarcts and bleedings. Thus, from our perspective, in the vast majority of cases there is no reason to assume that reported impairments will be permanent and not responsive to treatment,” says Dr. Philipp T. Meyer, MD, PhD, head of the Department of Nuclear Medicine of the Freiburg Medical Center.
Another benefit of optimizing molecular imaging for patients with COVID-19 is that if COVID-19 infection is advancing the progression of neurodegenerative diseases such as Alzheimer’s or Parkinson’s, the team suggests molecular imaging could help identify those patients at risk of developing it.
The study is published in The Journal of Nuclear Medicine.