As populations around the world age, dementia -; often caused by Alzheimer’s disease and related disorders -; is a growing health problem for older people worldwide. While it may seem like COVID-19 has little in common with these disorders, researchers at Penn State College of Medicine say these illnesses may be related to each other.
A $1.6 million grant from the National Institute of Neurological Disorders and Stroke will support research to determine if COVID-19 contributes to the development of cognitive decline that may be part of the chain of events leading to dementia.
Centers for Disease Control and Prevention epidemiologists estimate that just under a third of all COVID-19 cases have occurred in people age 50 and older. This same group is also at increased risk of having or developing a neurodegenerative disease. Patients with COVID-19 often report neurological symptoms such as memory problems, “brain fog”, and loss of smell and taste; some symptoms persisting months after diagnosis. Some research also suggests that these patients are at a higher risk of being diagnosed with dementia as a result of their acute infection. These reports and others have led to scientific speculation that COVID-19 infections may contribute to premature cognitive decline, the researchers said.
To investigate whether there is a link between COVID-19 infection and neurocognitive decline, Dr. Xuemei Huang, Professor Emeritus of Neurology, Pharmacology, Neurosurgery, Radiology and Kinesiology at the College of Medicine and Head of the Division of Brain Disorders movement at Penn State Health Milton S. Hershey Medical Center will lead a multidisciplinary team to collect additional information and biological samples from participants in their past and current studies. The study will leverage resources from a multi-year, $3.8 million project that aims to identify biological signs (biomarkers) of Parkinson’s disease and related disorders through magnetic resonance imaging (MRI) scans ) and molecules in biological samples including blood, skin, and cerebrospinal fluid.
“We have a unique opportunity to study whether COVID-19 infection contributes to the progression of neurodegenerative diseases,” said Huang, who also directs the Center for Translational Brain Research. “Parkinson’s disease and related disorders often lead to dementia in the end, and we hope to better understand whether COVID-19 infection affects the process of neurocognitive decline in our research participants.”
In the same way that loss of smell has signaled COVID-19 infection in some people, some scientists hypothesize that loss of smell also signals the onset of neurodegenerative processes that lead to both Parkinson’s disease and Alzheimer’s. This can come from a person’s continued exposure to viruses and environmental toxicants that enter through the olfactory system (nose and nasal passages); a concept known as the olfactory vector hypothesis of neurodegenerative diseases. SARS-CoV-2, the virus that causes COVID-19, is an example of a virus that enters the body through the olfactory system.
The research team will collect information on the history of COVID-19 infection, vaccination status, ongoing exposure to environmental toxins, medical history and other lifestyle factors from more than 500 participants to their past and current research studies -; some with Parkinson’s disease and related disorders and some healthy. Huang’s team has data on these participants that was collected before the current pandemic. The team will use brain MRI scans to identify possible changes in brain anatomy similar to those that occur in Parkinson’s disease, and will also look for blood markers that occur in neurodegeneration.
We are still learning about the long-term effects of the pandemic and the effects on those who have fallen ill. This research will increase our understanding of whether or not COVID-19 infection contributes to the development or progression of neurodegenerative diseases.
Xuemei Huang, Distinguished Professor of Neurology, Pharmacology, Neurosurgery, Radiology, and Kinesiology, College of Medicine and Division Chief of Movement Disorders, Penn State Health Milton S. Hershey Medical Center