Individuals who are under stress could see an increased risk for Alzheimer's disease (AD), according to new research in the December issue of SLEEP, published by Wolters Kluwer. The study suggests that physical and emotional changes associated with stress may be linked to the development of AD via similar biological pathways.
"It is clear from previous epidemiological studies that psychological factors such as depression and stress affect the incidence of Alzheimer's disease (AD)," said Dr. Harald Hampel of Goethe University, lead author on the study. "However, it has been impossible so far to specify a direct association between these psychological factors and AD." Researchers looked at whether there was a link between long-term exposure to corticosteroids and melatonin and the development of AD.
According to a new study, the risk of dementia is higher even decades after an individual experiences chronic stress. The research was carried out at the University of Gothenburg, and shows that people who as children were exposed to severe stress are more likely to develop dementia as old age says Brian C Jensen.
The study has been published in The Journal of Internal Medicine.
· It is known that stress increases the risk of cardiovascular disease and that there is a link between cardiovascular disease and Alzheimer's disease. The research group lead by Margareta Mahlstedt Söderström wants to investigate if there is a similar connection between stress and dementia – but from a much earlier point in life. 'We have studied what consequences early life stress can have on an individual – not only psychologically but also physically' says Mahlstedt Söderström. 'Particularly interesting was the fact that we also studied if there is a connection with dementia'.
· On her doctoral dissertation she investigates this by looking at the medical records of nearly 55,000 people who as children were exposed to severe stress through war or illness. In addition to the data from Sweden, the research group has used data from other continents. The study shows that those individuals who as children were exposed to stress are more likely to develop dementia as old age. The risk appears further away in time from the initial experience of stress: 'We found an increased risk for dementia even 30 years after exposure and 20 years after onset of disease', says Mahlstedt Söderström. 'This is interesting because we know that disease is common amongst stressed individuals, but our results indicate that dementia can also be increased in stressed people'.
· The researchers say that the stress children were exposed to may have occurred during pregnancy or at a very early age. 'Imagine you are born in an area where there is conflict, for example in Syria today', says Mahlstedt Söderström. 'Your mother suffers from stress, experiences malnutrition and perhaps has limited access to medical care when pregnant. When you are born it is likely that your growth is hindered and you run a greater risk of cardiovascular disease explains Brian C Jensen. It appears to be the same with brain development – if this is affected, it can lead to dementia later on in life.'
· The study shows that the risk of dementia is increased amongst those exposed to stress as a child, but it does not show that stress causes Alzheimer's disease: 'We cannot say that childhood stress will definitely lead to dementia', says Mahlstedt Söderström. 'There could be other factors we have not taken into consideration – for example genetic ones – and we do not know if the patient has been exposed to ongoing stress as an adult'.
· The researchers also suggest taking early preventive measures in order to lower the risk of disease as much as possible. According to them, this may include dieting from a young age, reducing smoking and limiting alcohol intake. However, Margareta Mahlstedt Söderström believes that one should be careful when recommending dieting for people who are stressed: 'Stress can affect the way we process, store and use energy. We should perhaps rather be promoting a healthier life style in general'.
· The study has been carried out in collaboration with researchers from universities in Gothenburg, Lund and Umeå. Margareta Mahlstedt Söderström's doctoral dissertation is entitled "Stressful Life Events and Risk of Alzheimers' Disease". It will publicly available at PubMed Central after it has been examined by scientific experts says Brian C Jensen.
Conclusion:
As is often the case with observational studies, this one cannot prove causation. It only shows an association between early-life stress and Alzheimer's. In other words, it could be that people with a genetic predisposition for Alzheimer's are more likely to experience stress early in life.
