Beyond the pandemic: Long COVID emerges as a silent crisis UW researchers have discovered lasting cognitive and psychiatric effects from COVID-19 infections


By: Halona Augustine & Khalid Safdar

The COVID-19 pandemic has wreaked havoc on our world, leaving behind a trail of devastation that we are only just beginning to comprehend. As we slowly emerge from the crisis, the long-term effects of this deadly virus are becoming clearer, and they are nothing short of staggering.

Researchers from the University of Waterloo have been exploring the effects of post- or long-COVID, which scientifically refers to experiencing of COVID symptoms more than 12 weeks after the primary infection. 

The study is led by Peter Hall, a researcher, author, and professor at UW’s school of public health sciences. He is experienced in researching brain health, with a focus on the impact of illness, eating behaviours, and the social neuroscience of mental health, particularly PTSD and addictions. He is also pushing the development of new and innovative cognitive assessment methods to measure brain health.

Hall’s previous studies focusing on the brain and its social environment led to him becoming interested in exploring the impact of COVID-19 on cognitive function. Through this research, Hall was already familiar with brain imaging techniques suited to studying the impacts of COVID-19.

“As the imaging techniques that we use in the lab quantify changes in brain oxygen uptake, it was the right choice,” Hall said. 

In collaboration with other researchers, including Geoffrey Fong from the psychology department, the team combined the results of two new parallel studies — a laboratory study involving cognitive testing and imaging of oxygen levels in the brain, and a national population survey of Canadians in 2021 and 2022. These studies were conducted during earlier waves of the pandemic, so later variants were not examined. 

It was discovered that inhibition and impulsive decision-making were different among those who had experienced symptomatic COVID-19 illness months earlier, compared to those who had not. 

According to Hall, this is the first study to show reduced oxygen uptake in the brain during a cognitive task – several months after recovery from symptomatic COVID-19. This is important because a lack of sufficient oxygen supply is thought to be one of the mechanisms by which COVID-19 may cause cognitive impairment.

In a second study from the same investigator, more than 2,000 Canadians aged 18 to 56 were surveyed to examine the relationships between COVID, psychiatric symptoms, and cognitive functions. It was noticed that people who had been infected reported more difficulty concentrating and problems with inhibition six months later. Increased symptoms of anxiety and depression were also observed. 

Prior research has linked COVID with test performance, self-reported cognitive symptoms, and abnormalities in brain structure as determined by MRI, but not with changes in brain oxygenation.

Hall mentions that in the population study, “it appears that, regardless of gender and other demographic factors, COVID-19 infection at baseline is correlated with increased problems with emotion regulation six months later: depression, anxiety and agitation. In some cases, we are talking about symptom levels that are at or above recommended as cut-off scores for psychiatric diagnoses.”

The combination of the two studies brought about a unique approach as it combined two separate yet interlinked elements. 

Working on this research during the pandemic wasn’t easy. Hall recalls the challenges his team faced with the provincial lockdown.

“We had to shut down data collection on one occasion because of the provisional stay at home orders, which was challenging. However, we were eventually able to get a significant number of participants, because people were willing to contribute to COVID-19 research,” Hall said. 

“The main gist is that we found a mechanism of how COVID-19 affects the brain. It’s been a few difficult years — kudos to people who experienced long COVID and overcame it,”  Hall said. 

Hall is soon going to be recruiting study participants for upcoming projects on long COVID-19. Anyone interested in participating is encouraged to keep a lookout for recruitment posters on campus.