Alzheimer’s & Stress
Stress is our body’s natural response to adverse or demanding changes in our environment, developed as a measure to manage and overcome these challenges to our wellbeing. This process is essential for our survival, but it can become maladaptive and lead to problems (1).
Stress has been shown to drive the disease processes of Alzheimer’s. In fact, stress has even been found to negatively impact Alzheimer’s-related genes. In animal studies, rats and mice exposed to stress had increased expression of amyloid precursor protein (APP) (2). This is a key gene that leads to more production of amyloid beta peptide, which increases amyloid plaques. As we learned in Part One of this series, amyloid plaques are a hallmark of Alzheimer’s.
In the Rush Memory and Aging Project, participants were tested for neuroticism - a psychological trait which is characterised by being more highly strung and prone to distresss. We all know one or two neurotics! They found that those who scored highly on this scale were almost three times as likely to receive a dementia diagnosis within the subsequent three years (2).
One mechanism by which stress may exacerbate Alzheimer’s is through the hypothalamic pituitary adrenal (HPA) axis, which upon activation increases cortisol production (2). This hormone can cross the blood-brain barrier and enter the brain. Sustained elevated cortisol levels have been proposed to initiate amyloid beta accumulation and tau pathology in Alzheimer’s. In fact, Alzheimer’s patients have ~83% higher cortisol levels in their cerebrospinal fluid compared to healthy age-matched controls (1).
Chronic stress occurs when the stress response does not resolve, and continues to perpetuate, potentially causing serious psychological and physiological health problems, including neurodegenerative diseases (1). Chronic psychological stress may accelerate biological ageing, with oxidative stress (another critical player in Alzheimer’s disease) a key mediator (3). Those experiencing chronic stress, such as a carer of a sick spouse or child, experience higher levels of oxidative stress due to sustained activation of the HPA-axis. Those who are chronically stressed have a heightened tendency to anticipate stress, leading to a surge in cortisol release, increasing vulnerability to oxidative stress and accelerated biological ageing. Therefore, there is a vicious cycle of stress leading to more stress! This is just another reason why stress management is so key.
Chronic stress has been found to impair microglia - immune cells within the brain (1). When these cells are functioning normally they are very health-promoting neurologically. However, when they are dysfunctional as occurs with chronic stress, they become pro-inflammatory and a significant source of oxidative stress. This leads to further neuro-degeneration in Alzheimer’s.
Good Stress, Bad Stress: The Importance of Perception
Not all stress is bad. In fact, short exposures to high cortisol levels as occurs with low-to-moderate stress may improve mitochondrial (cellular energy production) function and have neuro-protective effects (3). This highlights the importance of identifying “good stress,” which is helpful to the brain and “bad stress”, which is detrimental. The key difference in these stress types has been shown to be the attitude toward stress, or the “anticipatory stress”.
Amazingly, it has been shown that those exposed to chronic stress experience morphological changes in the brain, leading to compromised and exaggerated responses to stress and its anticipation - that vicious stress cycle! It is the psychological processes prior to an expected stressful event such as expectations, thoughts and emotions that are the key players in determining the level and detriment of stress (3).
While we may not be able to control many external factors, we can choose how we plan, think, and feel about our environment and our stressors. This means we actually have the power to decide how we choose to relate to our stress, and therefore whether stress impacts us positively or negatively.
One technique we can use is to shift our self-talk around stressful situations. For example, if you have a heavy workload, one way of thinking is: “There is so much work. I can’t handle this. I am so overwhelmed. I am going to fail”. This sets an expectation of failure and hardship with no positive outcome. It is also riddled with self-doubt and negative affect.
Now let’s think of the same situation, a heavy workload, but with a different approach of thinking and relating: “There is so much work. I have an opportunity to challenge myself. It’s going to be difficult, but I will get it done. I’m going to learn and grow from this”. While discomfort is also acknowledged here, it is instead framed in a positive way. The stress of carrying out the work is the same in both instances - it’s the same amount of work in the same timeframe - but the stress of THINKING about the work is a lot greater in the first example.
So when you next realise you are ruminating over an upcoming event, try noticing your thought patterns and see if you can find and focus on a positive within the situation.
Unwinding Through Yoga & Meditation
Mindfulness involves the ability to direct attention within the present moment, in a manner that is non-judgmental, to allow one to foster and develop awareness (4). The more physical practice of yoga involving postures or asana also emphasises awareness and attention, but by focusing more on breathing, and specific muscles or parts of the body (5). Mindfulness is proposed to promote healthy ageing through several mechanisms including enhanced attention, neural function preservation, improved psychological well-being, and even reduced inflammation (4). The negative impact of stressful events can be mitigated through mindfulness by encouraging mental flexibility, and reducing internalising of distressing thoughts with one’s sense of self and psyche (4).
Practices of meditation and yoga have shown promise in attenuating some of the symptoms associated with Alzheimer’s and cognitive decline. A preliminary study has indicated that this may be due to protective or therapeutic neurotransmitter changes (6). Small studies have shown a trend toward improved cognition, quality of life and wellbeing following mindfulness interventions (4).
Mindfulness meditation, but not relaxation, has been found to alter function and physiology of the amygdala - part of the brain involved in processing psychological stressors and coordinating stress responses (7). Practising yoga and meditation consistently can help you manage your stress by literally changing your brain, but also potentially by helping you dissociate from catastrophising thought patterns that create “bad stress” and prevent “good stress”.
There are many ways to improve stress levels. Start by identifying the key sources of stress within your life. Notice how you relate to your stress, and see if you can shift your thinking about stress to something more positive. Then introduce practices into your daily life that help you relieve stress, and optimise your self-talk and outlook. Meditation, mindfulness and yoga classes are great, but there are other options too like walking meditation. Find what suits you best and develop a consistent practice!
Written by Jessica Zabow
Nutritionist (BHSc)
& Yoga Teacher (RYT500)
References:
Bisht, K., Sharma, K., & Tremblay, M. (2018). Chronic stress as a risk factor for Alzheimer’s disease: Roles of microglia-mediated synaptic remodelling, inflammation, and oxidative stress. Neurobiology of Stress, 9(1), 9-21. https://doi.org/10.1016/j.ynstr.2018.05.003
Justice, N.J. (2018). The relationship between stress and Alzheimer’s disease. Neurobiology of Stress, 8(1), 127-133. https://doi.org/10.1016/j.ynstr.2018.04.002
Aschbacher, K., O’Donovan, A., Wolkowitz, O.M., Dhabhar, F.S., Su, Y., & Epel, E. (2013). Good stress, bad stress and oxidative stress: Insights from anticipatory cortisol reactivity. Psychoneuroendocrinology, 38(9), 1698-1708. https://doi.org/10.1016/j.psyneuen.2013.02.004
Berk, L., Warmenhoven, F., van Os, J., & van Boxtel, M. (2018). Mindfulness training for people with dementia and their caregivers: Rationale, current research, and future directions. Frontiers in Psychology, 9(982), 1-10. https://doi.org/10.3389/fpsyg.2018.00982
Oken, B.S., Zajdel, D., Kishiyama, S., Legal, K., Dehen, C., Haas, M., Kraemer, D.F., … Leyva, J. (2006). Randomised, controlled, six-month trial of yoga in healthy seniors: Effects on cognition and quality of life. Alternative Therapies in Health and Medicine, 12(1), 40-47. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1457100/pdf/nihms9803.pdf
Hassan, A., Robinson, M., & Willerth, S.M. (2020). Determining the mechanism behind yoga’s effects on preventing the symptoms of Alzheimer’s disease. Neural Regeneration Research, 15(2), 261-262. https://doi.org/10.4103/1673-5374.265553
Taren, A.A., Gianaros, P.J., Greco, C.M., Lindsay, E.K., Fairgrieve, A., Brown, K.W., Rosen, R.K., … Creswell, J.D. (2015). Mindfulness meditation training alters stress-related amygdala resting state functional connectivity: A randomised controlled trial. Social Cognitive and Affective Neuroscience, 10(12), 1758-1768. https://doi.org/10.1093/scan/nsv066