Current tests often misdiagnose concussion symptoms for people who are bilingual

Somayya Saleemi, PhD student, Department of Clinical Psychology, University of Ottawa

Bilingual Canadians who suffer a brain injury may not be getting the help they need. A University of Ottawa doctoral student is working to change that with a new study that takes aim at outdated assessment tools designed decades ago with participants who were primarily white, male, middle-class and English-speaking.

"There isn't much research out there in terms of how people who are bilingual are affected by a mTBI (mild traumatic brain injury)," says Somayya Saleemi, whose research is supported by a Canada Graduate Scholarship from CIHR. "There appears to be poorer outcomes for people who are bilingual. The reason for this isn't really known but I hope to shed some light on this through my research."

Those outcomes seem at odds with the "bilingual advantage" hypothesis that learning a second language can strengthen executive functions, such as attention, working memory and cognitive control, as well as serve as a protective factor against neurodegenerative disease.

"Specifically for bilinguals there is an advantage when it comes to compensation for memory and delayed onset of dementia that has been found. But the exact neural mechanism for that is unclear," says Saleemi, who studies the effects of bilingualism on cognition and aging at the University of Ottawa's Cognitive Neuroscience of Bilingualism Laboratory. The new lab uses magnetic resonance imaging (MRI), electroencephalography (EEG), and behavioural measures to understand the links between bilingual language experience, cognition, and brain structure and function.

At issue is the neuropsychological testing commonly used to assess how well a person's brain is working after a mTBI. These tests rely heavily on verbal measures such as reading comprehension, language usage, memory, attention and reasoning. Research has shown that bilinguals with a history of a mTBI often perform worse than monolinguals on these assessments. (Ratiu, I., & Azuma, T. (2017), Ratiu, I., & Azuma, T. (2020)).

"These types of paper and pencil tasks do not always capture the true cognitive performance of bilinguals," explains Saleemi. "As a result, we don't know if the deficits are because of the brain injury or because of the measures being heavily dependent on verbal processing and being normed on samples that are not reflective of society's current demographic make up."

To address this challenge, Saleemi has launched the first study that combines neuropsychological testing with brain imaging from EEG and MRI scans to compare monolinguals and bilinguals with and without a history of a mTBI.

"We're also looking at the function of the brain," she adds. "A functional MRI measures the flow of oxygen to tell which parts of the brain are being used or oscillated while you're at rest or doing a task like remembering numbers. Combining these two methodologies [EEG and MRI] allows you pick up on both the spatial and temporal activity in the brain so you can identify what parts of the brain are activated differently."

Over- or underestimating the impact of a mTBI can have lifechanging consequences for those affected. Patients may receive the wrong interventions, if any at all. Long-term effects from mTBI can include dizziness, depression, light sensitivity, headaches, fatigue and short-term memory impairments. One of the most feared consequences of a brain injury is the increased risk of developing dementia later in life.

"Until now people haven't really been treated differently based on whether they're bilingual or monolingual. It's all been lumped into one group," she says. "The more we know about how the brain is affected, the better we can develop the evidence-based assessments and treatments that lead to better outcomes for all patients."

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