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What is stress?

It has been defined in a number of different ways but for the purpose of this article, is taken to be: a sense of irritation, tension, nervousness, anxiety, fear or difficulty sleeping, lasting over a month as a result of problems at home, at work or health worries.

Stress is a term often used in society, but do we really understand what stress actually is and why it matters to brain health?

Should we worry about stress as a risk factor for dementia and Alzheimer’s?

Severe chronic stress is bad for our health. This is the sort of stress that keeps you awake at night with worry. This is the sort of stress that is associated with excessive release of catecholamines, the substances associated with the “flight or fight” syndrome. Here cortisol, which in normal amounts causes no problem, exerts a toxic effect on our neurons.

Studies looking at dementia risk and stress.

A high level of cortisol in the brain, by accelerating the process of biochemical and behavioural pathology, has been linked to an increased risk of dementia.

The results of a population study on a group of 1400+ women in Sweden followed for over 35 years from 1968 was published in 2010. They were aged between 38 and 60 when first recruited to the study and answered questions including one asking about psychological stress in 1968, 1974, and 1980.

Of the group, 161 women developed dementia (mostly in the form of Alzheimer’s disease). Those who had reported having repeated periods of stress in middle age were shown to have a 65% increase in their risk of dementia. In those who reported stress in all three surveys had double the risk. In this study, the timing of the stress was relevant. In other words, exposure to repeated stress in middle age appears to elevate the risk

Should this be a surprise? Maybe not. It is already known that stress has a negative impact on our health, increasing our susceptibility to an impaired immune response and an increased risk of cardiovascular disease in the form of stroke, high blood pressure and heart attack.

Previous animal studies had also previously shown an association of stress and dementia risk.

But it also needs to be put into perspective. The vast majority of women participating in the study did not develop dementia. So while stress is significant and needs to be dealt with appropriately, it is important not to stress, that being stressed will lead you to developing dementia!

In another study, the physiological changes in neurons susceptible to the effect of stress were examined were examined.
Here, researchers using rats, showed how stress led to an increase in the formation of abnormal clumps of tau protein in neurons. This led to increased cell death, particularly in the area of the brain associated with learning and memory i.e. the hippocampus and prefrontal cortex.

This builds on previous findings that stress is associated with the build up of beta amyloid, another protein associated with the pathology of Alzheimer’s disease.

The next step will now be to examine to see whether these results implicating stress as a possible trigger of neurodegenerative disease can be replicated in humans. One of the researchers Osborne Almeida, has also questioned the relationship between stress and depression. Stress has been recognised as a major risk to a person’s propensity to develop major depression. Could beta amyloid and tau proteins, by being accelerated to form under the influence of stress, be implicated in the development of this disease as well?

Stress Management: The need to manage stress levels.

The bottom line is that the effect of stress on our health and well-being should not be underestimated.

• Be aware that stress is potentially harmful to your health.
• Make sure you know what you can do and how you can mitigate the effects of stress.

This could be in the form of physical exercise, talking to a trusted friend or family member, seeking medical advice, learning meditation, practicing yoga or tai chi, deep breathing or mindfulness training.

So don’t ignore symptoms of stress either personally or in someone else. Take the necessary steps to bring your stress under control and minimise any potential risk to the health of your body and brain.


L. Johansson, X. Guo, M. Waern, S. Ostling, D. Gustafson, C. Bengtsson, I. Skoog. Midlife psychological stress and risk of dementia: a 35-year longitudinal population study. Brain, 2010; DOI: 10.1093/brain/awq116

Ioannis Sotiropoulos, Caterina Catania, Lucilia G. Pinto, Rui Silva, G. Elizabeth Pollerberg, Akihiko Takashima, Nuno Sousa, and Osborne F. X. Almeida. Stress Acts Cumulatively to Precipitate Alzheimer’s Disease-Like Tau Pathology and Cognitive Deficits. Journal of Neuroscience, May 25, 2011; 31(21):7840-7847 DOI: 10.1523/JNEUROSCI.0730-11.2011

Dr Jenny Brockis

Dr Jenny Brockis is a medical practitioner and internationally board-certified lifestyle medicine physician, workplace health and wellbeing consultant, podcaster, keynote speaker and best-selling author. Her new book 'Thriving Mind: How to Cultivate a Good Life' (Wiley) is available online and at all good bookstores.

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