Stressful experiences in middle age can cause a greater risk of Alzheimer's in adulthood, in the same way that if they occur during childhood they are associated with a greater chance of developing neuroinflammation.
This is concluded by a study led by the Barcelona Institute of Global Health (ISGlobal) published in Annals of Neurology. Scientists have investigated the association of cumulative life events with Alzheimer's pathologies, neuroinflammation and gray matter volume in a cohort of 1,290 people aged 48 to 77 years without cognitive impairment.
Participants conducted interviews to assess the number of stressful life events, those in which external threats activate behavioral and psychological responses: illness, unemployment, or the death of a loved one, for example. Likewise, lumbar punctures and magnetic resonance imaging were performed to analyze different biomarkers related to Alzheimer's.
Statistical analyzes associate the accumulation of stressful experiences in middle age with higher levels of B-amyloid protein, a key factor in the development of Alzheimer's disease.
Regarding stressful experiences in childhood, the research team associates them with a greater risk of neuroinflammation at older ages. A conclusion that is consistent with new evidence linking childhood trauma to an increase in inflammation (a key molecular response in neurodegenerative diseases) in adulthood.
Life stressors have different effects depending on gender, according to the study. While only in men they are associated with higher levels of B-amyloid protein, in women they are linked to lower levels of gray matter.
In the case of people with a history of psychiatric diseases, they lead to increased levels of AB and tau proteins, neuroinflammation and lower gray matter volume, “which suggests that this population could be more susceptible to the effects of stressful life events, for example. For example, due to a lower ability to cope with stress that could make them more vulnerable,” the researchers point out.
According to Eider Arenaza-Urquijo, a researcher at ISGlobal, the work reinforces the idea that stress can play a fundamental role in the development of Alzheimer's and “provides initial evidence on the mechanisms underlying this effect,” but additional research is needed to validate these findings.
Dementia affects more than 50 million people worldwide and Alzheimer's disease is the most common cause. It is characterized by the accumulation of B-amyloid and tau proteins in the brain, neurodegeneration, progressive cognitive impairment, and neuroinflammation.
Several psychological risk factors have been identified, such as depression, anxiety or chronic stress, but there is less research focused on the relationship between stressful life events and Alzheimer's biomarkers.
The research group recalls that psychosocial interventions can improve resilience to stress in people with high exposure to traumatic events who are at risk of cognitive impairment. “Future research is needed to refine the identification of risk profiles that would benefit most from this type of intervention,” he concludes.
