Aug 30, 2023

Long COVID symptoms may be caused by neuroinflammation

A woman leans against a window while wearing a medical mask. Her expression is tired and sad.
By Ben Gane

While most people who have a mild or moderate case of COVID recover quickly, some experience symptoms that last for months or even years. Known as Long COVID, symptoms can include fatigue, depression, and a recurring confusion nicknamed “brain fog”. Long COVID can have a severe impact on quality of life, and its causes are still poorly understood.

Dr. Jeff Meyer and his team are researching long COVID. The research team includes graduate student Joeffre Braga and is primarily funded by the Canadian Institutes of Health Research, works at the Brain Health Imaging Centre at CAMH. They believe that some symptoms, such as brain fog and depression, could be caused inflammation in the brain. Their recent study indicates there may indeed be a link – and has important implications for how we can treat long COVID.

Dr. Jeff Meyer
Dr. Jeff Meyer

What is neuroinflammation?

JM: Inflammation is the body's response to infection or damage, like the redness you see around a scrape on your skin. Neuroinflammation is a similar response that takes place in the brain when immune cells become active in response to a threat.

What motivated this research?

JM: Clinical depression and brain fog are symptoms of long COVID, occurring in about 5% of cases, and inflammation has been identified as a potential cause. Long COVID can be debilitating and have a drastic impact on the lives of people experiencing it. We need to understand the mechanisms of long COVID to treat it.   

What was the most important finding of this study, in your opinion?

JM: We found that individuals suffering from long COVID had inflammation in a specific part of the brain. We know that injuries to this part of the brain can reduce our ability to enjoy things, maintain movement speed, and experience motivation. The loss of these abilities matches key symptoms identified by our study participants suffering from long COVID. 

How does this change treatment in the future?

JM: This research indicates there are two directions that are worth exploring to identify potential treatment. One is that inflammation altering medications could be tested in long COVID patients, targeting symptoms in brain regions where we found inflammation.  A second direction is learning more about the area of brain where we found inflammation and using this knowledge to create targeted treatments. 

Any next steps?

JM: In addition to inflammation altering medications and more detailed analysis of this specific part of the brain, we believe it is also worth examining the different types of inflammation present in the brains of those with long COVID, and studying how they relate to different symptoms.

What is the major take home message for the public?

JM: Long COVID patients appear to have inflammation in a specific part of the brain. We know that injuries to this part of the brain are linked to the loss of the ability to enjoy things, maintain movement speed, and feel motivated. We are very interested in using this knowledge to develop new treatments. As researchers, we haven't forgotten about those living with long COVID. It is important to remind funding agencies to support this work so it can continue.

ImPACT logo: Psychiatry articles that change treatment

ImPACT Committee includes Krista Lanctôt, Alastair Flint, Meng-Chuan Lai and Simone Vigod.

Braga J, Lepra M, Kish SJ, Rusjan PM, Nasser Z, Verhoeff N, Vasdev N, Bagby M, Boileau I, Husain MI, Kolla N, Garcia A, Chao T, Mizrahi R, Faiz K, Vieira EL, Meyer JH. Neuroinflammation After COVID-19 With Persistent Depressive and Cognitive Symptoms. JAMA Psychiatry. 2023 May 31:e231321. doi: 10.1001/jamapsychiatry.2023.1321. Epub ahead of print. PMID: 37256580; PMCID: PMC10233457.