A new study highlights the potentially devastating impact of stress on the human brain, revealing that it can significantly increase the risk of dementia.

Conducted by researchers at the Karolinska Institutet in Sweden and published in Alzheimer’s & Dementia, the study suggests that stress can erode cognitive defenses, making individuals more susceptible to the debilitating disease.

The researchers explored the connection between daily activities and cognitive health, focusing on the concept of “cognitive reserve.” This reserve is built through mentally stimulating activities such as higher education, complex jobs, physical exercise, and a vibrant social life. It acts as a mental buffer, protecting the brain from the symptoms of dementia, even when physical signs of the disease are present.

Despite the protective effects of cognitive reserve, the study found that high or persistent stress levels could undermine these benefits. Stress appears to act as a cognitive thief, reducing mental resilience and increasing the risk of dementia. This is particularly concerning given that stress is known to decrease social interactions, hinder engagement in leisure activities, and elevate dementia risk.

Lead author Manasa Shanta Yerramalla, a researcher at the Department of Neurobiology, Care Sciences and Society at Karolinska Institutet, suggests that stress management strategies could complement existing lifestyle interventions aimed at preventing Alzheimer’s disease.

The study involved 113 participants from the memory clinic at Karolinska University Hospital. Researchers examined the relationship between cognitive reserve, cognition, and biomarkers for Alzheimer’s disease, while also considering the impact of stress.

They measured physiological stress using cortisol levels in saliva and psychological stress based on participants’ self-reported stress levels. Cortisol, often referred to as the “stress hormone,” rises in response to pressure and acts as the body’s alarm system.

Results showed that greater cognitive reserve did improve cognition. However, higher cortisol levels weakened this beneficial relationship, indicating that stress was eroding the protective layers of cognitive reserve.