Around 50 million people worldwide are affected by dementia, and this figure could well triple by 2050. Now, Spanish researchers say people who experience stressful life events may be at greater risk of developing Alzheimer’s disease later in life.
To reach this conclusion, the authors of this study, published in Annals of Neurology, focused on 1,290 participants – volunteers with no cognitive impairment at the time of the study, but who have Alzheimer’s disease in their family.
They were asked about the number of stressful events in their lives – death of a loved one, period of unemployment, illness and so on – the frequency of these occurrences, and their age at the time they experienced them. The researchers at the Barcelona Institute for Global Health (ISGlobal) also carried out clinical tests (lumbar punctures and MRI scans) to detect biomarkers of Alzheimer’s disease.
After analysing the data, they found that the accumulation of stressful experiences during midlife was associated with higher levels of beta-amyloid (Aβ) protein, which plays a key role in the development of Alzheimer’s disease.
“We know midlife is a period when Alzheimer’s disease pathologies start to build up. It is possible that these years represent a vulnerable period where experiencing psychological stress may have a long-lasting impact on brain health,” said Eleni Palpatzis, ISGlobal researcher and first author of the study.
Childhood may also be a significant period: experiencing stressful events at an early age was found to be associated with a higher risk of developing neuroinflammation later in life.
“Inflammation has been recognised as a key molecular response in neurodegenerative diseases, and these results are in line with emerging evidence suggesting childhood trauma to be linked with increased adulthood inflammation,” the study explained.
The researchers also found that the effects of stressful life experiences can differ according to gender.
In men, a greater number of stressful events was linked to an increase in Aβ protein. In women, they noted a reduction in the volume of grey matter in the brain, which is made up of nerve cells and plays a crucial role in our cognitive functions such as reading, calculation, attention and memory.
Individuals with a history of psychiatric disorders appeared to be more susceptible to the effects of stressful life events. For these individuals, stressful life events were associated with increased levels of Aβ and tau proteins, neuroinflammation, and lower grey-matter volume.
There are, however, certain limitations to this study: the research reveals that relying on participants’ memory to recall stressful events can bias the results. Moreover, measuring stress does not necessarily take into account the personal impact it has, or the severity of the events.
“Our study reinforces the idea that stress could play a significant role in the development of Alzheimer’s disease and provides initial evidence regarding the mechanisms behind this effect, but additional research is needed to replicate and validate our initial findings,” the study concluded.