Researchers have uncovered how a previously overlooked form of indirect brain injury contributes to lasting disabilities following a stroke. The study highlights that the thalamus—a central hub that manages key functions such as language, memory, attention, and movement—can be impacted months or even years after a stroke occurs, despite not being directly harmed. These discoveries have the potential to pave the way for new treatments that may lessen the persistent challenges of chronic stroke, which is a major cause of disability globally.
A recent study from Simon Fraser University researchers has revealed how an overlooked type of indirect brain damage contributes to ongoing disability after a stroke.
The findings, published in Proceedings of the National Academy of Sciences, indicate that although the thalamus itself is not directly damaged during a stroke, it can still be adversely affected long after the incident. This opens avenues for potential therapies aimed at alleviating the burden caused by chronic stroke, a condition that continues to rank among the top causes of disability worldwide.
“Our research indicates that the indirect damage to the thalamus significantly influences the abnormal brain activity and long-term disabilities that frequently occur post-stroke,” states Phillip Johnston, the study’s lead author and a graduate student collaborating with Randy McIntosh at the SFU Institute for Neuroscience and Neurotechnology. “Unlike the brain areas that suffer irreversible damage from the stroke, the thalamus seems to remain somewhat functional. This gives hope that new treatment strategies may help restore its role or prevent it from being affected in the first place.”
In the study, researchers monitored the brain activity of 18 chronic stroke patients and applied computer models to analyze how this activity relates to impaired thalamus function compared to healthy individuals.
Investigating the brain activity and physical structure of stroke survivors, the SFU team found a correlation between the degree of indirect damage to the thalamus and the severity of a patient’s impairments.
Johnston notes that the thalamus has extensive connections throughout the brain via long fibers called axons, making it vulnerable to indirect harm. When strokes cause injury in other brain regions, this damage can extend to the thalamus and disrupt its functioning.
This disruption can further influence the activities that the thalamus usually oversees in other, healthy brain areas. Researchers believe that if treatments such as medications or brain stimulation can restore normal thalamic function or lessen the effects of damage coming to it, some of the long-lasting consequences of stroke could be alleviated.
“These revelations pose numerous new inquiries regarding which aspects of post-stroke disabilities arise from indirect thalamus damage versus those resulting from direct lesions,” McIntosh explains. “The thalamus may endure various types of damage after a stroke, and we need to determine whether a specific type or a combination thereof leads to the abnormal brain activity seen in our research. The next essential step involves exploring how indirect damage to the thalamus and related unusual brain activity develops over time, particularly in the initial hours and days following a stroke.”
The research was conducted in partnership with SFU’s Institute for Neuroscience and Neurotechnology as well as the Rotman Research Institute at the University of Toronto.
