Dementia: How stress affects our cognitive reserve

The progressive accumulation of amyloid plaques in the brain is one of the hallmarks of the onset of dementia, such as Alzheimer’s disease. However, some people with the same amount of plaques as others do not develop the same cognitive or memory problems. A disparity that could be explained by differences in levels of cognitive reserve, a sort of brain shield that prevents cognitive decline and dementia.

We know that cognitively enriching life experiences, intellectual stimulation, physical and artistic activities, or even social interactions help build this cognitive reserveas well as the complexity of the profession and reading ability. But according to a team of researchers from the Karolinska Institute in Sweden, all our efforts to sharpen our brains could well be undermined by… stress.

The harmful effects of stress on our cognitive reserve

As part of their work, published in the journal Alzheimer’s & Dementiascientists examined the association between the cognitive reserve index (education, activities, social health…), cognitive performance and biomarkers associated with Alzheimer’s disease in 113 patients from the “memory clinic” from Karolinska University Hospital, according to a statement.

During a three-year follow-up, they also examined how this association was modified by physiological stress, i.e. the level of cortisol in saliva, and psychological stress, i.e. the stress perceived by the participant.

It turned out, unsurprisingly, that the greater the cognitive reserve a participant had, the higher their level of cognition, and therefore the lower their risk of cognitive decline. That said, the researchers found that “physiological stress (i.e., the body’s physical response to stressors, activation of the ‘fight or flight’ response, or hormonal changes) attenuated this association and reduced the benefits of cognitive reserve.”

Managing stress to prevent Alzheimer’s disease

“These results could have clinical implications, researchers estimate, because we now know that mindfulness exercises and meditation can reduce cortisol levels and improve cognition. Different stress management strategies could be a good complement to lifestyle interventions to prevent Alzheimer’s disease.”which affects more than 900,000 people in France, the majority of whom are women.

“Since stress disrupts sleep, which in turn disrupts cognition,” The team of scientists plans to study the association between stress and sleep disturbances in the future, and how this affects patients’ cognitive reserve.