Many people wonder whether stress is linked to risk of dementia, and the news often reports a link between the two. This Stress Awareness Month, our Research team decided to examine the evidence behind stress and risk of dementia.
What is stress?
Stress occurs when the body has to respond to a situation that could be dangerous. Symptoms include a pounding heart, sweating and tense muscles. These symptoms are supposed to fade away once the danger passes, but some people may find that these stressed feelings continue. This prolonged – or chronic – stress can be very serious and have severe effects on a person emotionally, mentally and physically.
Why has stress been linked to dementia?
There are many logical reasons why stress could be linked to dementia. Stress affects the immune system, which is known to play an important role in the development of dementia. A key hormone released when you’re stressed, cortisol, has been linked to problems with memory. Stress is also closely linked to conditions such as depression and anxiety, which have also been suggested as factors that could increase risk of dementia. Some research has found that stress appears to have a direct impact on some of the mechanisms underlying dementia in animal models.
However, as with many things in the research world, understanding whether any of these theories are correct has turned out to be a long and winding road.
A complicated situation
It is very hard for researchers to investigate stress. We all experience stress in different ways and our ability to cope with stress varies widely from person to person. It is also very difficult to measure exactly how stressed someone is. There are also other factors that could be playing a role that are difficult to separate out – for example the role of anxiety, depression and lack of sleep, all of which have been associated with increased dementia risk.
These complications mean that it is very difficult to do high-quality research into the role that stress has in dementia risk. However, a few studies have attempted to untangle this mystery.
What does the science say?
A review of the scientific literature on stress and dementia risk concluded that stress could play a role in dementia development but is unlikely to be the only factor that causes the condition. There is still much to be understood about what mechanisms could underlie any links between stress and dementia risk.
A study funded by Alzheimer’s Society is examining whether long-term stress may play a role in whether someone progresses from mild cognitive impairment (MCI) to Alzheimer’s disease. Lead researcher Clive Holmes says:
‘Understanding the role of the immune system in the risk of Alzheimer’s disease is of great importance to researchers. As prolonged stress can cause changes in the immune system, we wanted to find out if this was linked to progression to dementia from mild cognitive impairment.
‘Our investigations show that stress does appear to have an effect on progression in mild cognitive impairment. Our preliminary (unpublished) findings are showing that this may be mediated through a fault in the regulation of the immune system in people with mild cognitive impairment but we are continuing to investigate this further.’
Some researchers looking into long term stress and dementia have focused on people who are affected by Post Traumatic Stress Disorder (PTSD). This is a diagnosed condition that occurs when a person has been through a life-changing or distressing event. Research into the link between PTSD and dementia has found an increased risk, however having PTSD does not mean you will definitely develop dementia.
If I am affected by stress, should I worry about getting dementia?
The current evidence indicates that while prolonged stress may play a role in development or progression of dementia, having chronic stress does not necessarily cause dementia. Hopefully further research can begin to uncover what role, if any, stress does play in a person’s risk of developing dementia.
Having long-term stress does cause a number of health issues so if you are experiencing stress it is a good idea to see your doctor, especially if you might be affected by PTSD. There are a number of useful tools available now that can help to combat stress – the NHS Choices website has a list of many of them.