Chronic stress has been shown to increase the risk of a number of negative health outcomes, including heart disease, cancer and dementia. The means by which stress contributes to the development of these conditions, however, aren't as clear. But Swedish scientist Sara K. Bengtsson of Umea University may have an answer to the question of why chronic stress contributes to the development of Alzheimer's disease, the most common form of dementia.
Bengtsson's research thesis, which she will publicly defend at Umea University later this month, suggests that the elevated levels of stress steroids in the brain during periods of stress have the power to inhibit general brain activity.
Bengtsson found that chronically elevated levels of one particular type of steroid, allopregnanolon, accelerated disease development of two Alzheimer diseases models in mice. The mice with elevated levels of the stress steroid responded with impaired memory and learning early in the stage of disease development, when they normally would not display these symptoms. After a period of experiencing chronically high levels of allopregnanolon, the mice's brains also had higher levels of beta-amyloids, i.e. the proteins that form plaques between nerve cells in the brains of those with Alzheimer’s disease. Her work also showed that high levels of beta-amyloids were linked to brain synapse dysfunction.
An Umea University press release noted that a comparable acceleration of Alzheimer's disease in humans due to chronically elevated stress steroids could mean the difference between living independently and requiring professional assistance.
The research comes at an important time, as the disease is becoming more common but the causes remain poorly understood. More than 5 million Americans have Alzheimer's and one in eight older Americans live with the disease, according to the Alzheimer's Association. Moreover, the prevalence of the disease is expected to triple over the next 30 years.
The American health care system has already felt the impacts: The costs of caring for those with Alzheimer's and other types of dementia in America is estimated at $200 billion, $140 billion of which is in Medicare and Medicaid costs -- and this number is expected to spike to over $1 trillion by 2050 as cases of the disease continue to become more frequent.
The research points towards not only the need for more research, but also the importance of healthy lifestyles to reduce the risk of developing dementia.
“The greatest threat to our lives is our lifestyle,” stress expert Dr. Kathleen Hall told the Huffington Post. "If you slow down and get some relaxation techniques, it absolutely will effect your health outcome."
For older adults, Hall recommends physical exercises, brain training exercises, meditation, and the development of a strong social network to ward off stress and create a calmer lifestyle.