Researchers from the Karolinska Institute in Sweden have shown that stress can drain the brain’s cognitive reserve, a factor linked to a higher risk of developing dementia. The findings were reported in the journal Alzheimer’s and Dementia.
Cognitive reserve refers to the brain’s capacity to manage damage and discover new problem-solving approaches. It builds up over a person’s life and acts as a buffer against attention and memory difficulties. These ideas help explain why some individuals maintain sharper thinking longer, even in the face of aging or disease.
In a study involving 113 participants, researchers observed that when the cognitive reserve is depleted, it can have serious consequences. During the first phase, stress levels were evaluated with specialized tests, and saliva samples were collected to gauge cortisol, a hormone that helps the body adapt to changing environments and also influences blood sugar and blood pressure during moments of emotional and physical strain.
In the second phase, participants completed a suite of tests to measure cognitive performance and reserve. The results indicated that a richer cognitive reserve is associated with a lower risk of dementia. Yet both emotional stress and physiological stress, reflected in higher cortisol during the day, can erode cognitive reserve and lead to memory and attention problems over time.
Further findings suggest that higher physiological stress in the morning is linked to increased levels of tau protein in the brain. This protein can form plaques that disrupt neuronal function. Morning cortisol declines can reduce alertness and learning, while elevated cortisol in the evening may contribute to sleep disturbances, which are known to raise dementia risk. These insights align with broader research on sleep quality, stress hormones, and cognitive aging.
Earlier investigations have highlighted a rising incidence of dementia among younger populations, underscoring the importance of managing stress and building cognitive resilience early in life.