Strokes remain a leading cause of death and long-term disability worldwide, according to the World Health Organization. In the United States, someone has a stroke every 40 seconds, and someone dies of a stroke every three minutes and 14 seconds, based on data from The Centers for Disease Control and Prevention.
The danger is also wider than most believe, says Kristin Scaplen, Ph.D., a neuroscientist in Bryant University’s Psychology department. Scaplen notes that while strokes, which starve the brain of glucose and oxygen, are typically seen as brain injuries that affect the elderly, approximately 10 to 15 percent of strokes occur in children and young adults.
“This underscores why early detection and intervention is critical,” she explains.
But even after a devastating event like a stroke, there are still paths to recovery, as the brain doesn’t just heal — it rewires itself.
Below, Scaplen explores what happens to the brain during a stroke, its ability to make new connections between brain cells, and rehabilitation strategies for regaining lost abilities.
Know your stroke basics
There are two types of strokes, Scaplen explains: ischemic strokes and hemorrhagic strokes. Ischemic strokes are more common and occur when a blood clot blocks blood flow to a particular area of the brain. Hemorrhagic strokes happen less frequently and are caused by a burst blood vessel that cuts blood flow to nearby brain tissue.
“Think of the brain as the prima donna of your entire body,” Scaplen says. “It is incredibly metabolically demanding. It needs a constant supply of blood, oxygen, and glucose to function and even a brief interruption can have devastating consequences.”
The brain is made up of neurons and glial cells, shares Scaplen. Neurons are typically viewed as the “workhorse” of the brain, while glial cells support processing, such as enabling faster signal transmission, acting as insulation, and solidifying connections.
“If a region of the brain has a reduction in blood flow, it impacts the function of your neurons very quickly and they can start dying soon afterward” she says, noting that when brain cells are damaged during a stroke, the brain’s “janitor system,” known as the microglia, clears the dying neurons.
How the resulting damage affects a person’s cognition, movement, or speech depends on the part of the brain that was starved of oxygen and glucose. Scaplen notes that the acronym ‘BE FAST’ can help people recognize the signs of a stroke: Balance (loss of coordination), Eyes (changes in vision), Face (drooping features on one side), Arms (weakness in a limb), Speech (difficulty speaking), and Time (call 911 immediately).
Inside the brain’s restructuring
The brain promptly enters a period of restructuring following a stroke to cope with the changes — one that is remarkably similar to its initial development phase.
When you’re born, shares Scaplen, there are critical periods where the brain’s synaptic and neuronal plasticity — its ability to reorganize and adapt — allow individuals to learn a variety of things. Eventually, as the brain stabilizes itself, this plasticity window decreases.
“The brain’s perineuronal nets start to solidify some of the connections that are most important for the success of that individual,” Scaplen says.
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Following a stroke, the brain enters a new period of heightened plasticity — usually lasting about three months — as it works to reorganize itself. Taking advantage of that period for rehabilitation is crucial, says Scaplen.
“After three months, you enter this chronic period where it's not impossible to regain function, but it's significantly harder, and the gains are not equivalent to the effort being put in,” she states.
Re-training efforts
When it comes to post-stroke rehabilitation, working with the body’s natural processes is key. Because patients often rely on their stronger limb after a stroke, constraint therapy — which involves restricting the unaffected limb and forcing individuals to use the weakened side — is recommended.
“The idea is to reinforce neural connections during that critical window when you have optimal plasticity,” Scaplen says. “You've set the stage so that these neurons can sprout new axons and make connections.”
In addition to constraint therapy, mirror therapy is commonly used to help trick the brain into recovering. For this rehab exercise, individuals place a mirror next to their stroke-affected limb and align it with the stronger limb, so its reflection appears where the impacted limb would be. The individual then watches the mirror while moving the impacted appendage — creating the illusion of the affected limb moving normally.
This process relies on mirror neurons in the motor cortex that respond to observing others perform tasks and helps the brain both plan motor movements and reinforce function.
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“They're called mirror neurons because — to those neurons — there is no difference between whether or not you're doing that task or I'm doing that task,” she says. “They watch you perform that task and create a remarkably similar firing pattern that they then use to do that same thing.”
Social interactions and exercise are also great for helping the brain relearn, notes Scaplen, who adds that other new therapies are emerging as well, including the use of magnets to help induce plasticity in the brain and preclinical work that's exploring whether stem cells can help enhance the brain’s capacity to adapt and reorganize.
Ultimately, retraining neural circuits is much like learning a new skill, and recovery depends on repeated practice.
“Sometimes you're able to retrain some of those neurons if they didn't die off,” Scaplen says. “Other times, you're getting the surrounding neurons to take over.”