But it's not just the immediate effects on the brain we need to worry about; strokes also take a toll on our immune system. To help us understand this connection better, we spoke to Dr Ishu Goyal, Deputy Consultant, Neurology, Sir HN Reliance Foundation Hospital, Mumbai, who shared insights on how strokes impact our immune health and offered simple steps to reduce our risk. What Is A Stroke? "A stroke happens when a blood vessel becomes blocked or bursts, leading to damage in the affected area due to a lack of blood supply. The affected area has two parts: the core, which is the irreversibly damaged brain tissue, and the penumbra, which has reduced blood supply and can be saved with timely treatment," said Dr Goyal. According to the International Journal of Molecular Sciences, stroke ranks as the second leading cause of death and significantly contributes to disability globally. Its prevalence is particularly high in developing countries, with being the most frequently occurring type.   The Immune Response to Stroke "Once brain tissue is damaged, it is attacked by inflammatory mediators, such as macrophages, cytokines, and interleukins, which work to scavenge dead and necrotic tissue. The disrupted blood-brain barrier allows these inflammatory markers easy access to the affected area," said Dr Goyal. In response, the hypothalamic-pituitary-adrenal axis is stimulated to suppress an excessive inflammatory response after the stroke, limiting the area being targeted by inflammatory cells. "Interestingly, immediately after a stroke, a state of increased autoimmunity occurs within the brain, while systemic immunosuppression takes place. This dual response may predispose patients to various acquired infections, with pneumonia and being the most common in such cases," added Dr Goyal. According to a 2013 study, stroke patients encounter significant immunological challenges during their time in intensive care units, with pneumonia being the most prevalent and deadly post-stroke complication. A recent meta-analysis indicates that infections following acute ischemia can complicate recovery in as many as 30% of cases. Factors Influencing Immunosuppression Post-Stroke Several factors can influence the extent of immunosuppression following a stroke. Key factors include:

• Severity of Stroke: The more severe the stroke, the greater the impact on the immune system.
• Volume of Affected Area: A larger area of damage correlates with increased immune response issues.
• Pre-existing Comorbidities: Conditions, such as diabetes and hypertension can exacerbate immune dysregulation.
• Post-Stroke Complications: Hemodynamic disturbances and other complications can increase hospital stays and the risk of acquired infections.

According to a 2018 study, about 30% (ranging from 24-36%) of patients experience infections following a stroke, with pneumonia and Urinary Tract Infections (UTIs) being the most prevalent, each occurring in approximately 10% of cases.   Preventive Therapies and Strategies While various therapies have been proposed to prevent post-stroke systemic infections, such as stem cell therapies and beta-adrenergic blocking agents, these have not yet proven clinically effective. Consequently, the best approach to evade immune disturbances in the body is to prevent strokes in the first place. Managing Stroke Risk Factors To help manage stroke risk and associated immune dysregulation, it is essential to control risk factors such as:

• Diabetes: Maintaining healthy blood sugar levels can significantly reduce stroke risk.
• Dyslipidemia: Managing cholesterol levels through diet, exercise, and medication can lower the likelihood of stroke.
• Smoking: Quitting smoking is one of the most effective ways to decrease the risk of stroke.