From Psychology to Mitochondria
Every so often I read a paper that changes the way I think and I get very excited about this. I love learning about new ways to improve wellbeing and performance for the fast pace and challenges of life.
I didn’t anticipate diving into things at a cellular level, however, it turns out that understanding how our mitochondria perform has opened up my understanding of how we can support our body’s ability to adapt to stress and adversity and recover. It has also reconfirmed my pull towards Altitude Training and one of it’s main benefits; replenishing our mitochondria.
Below I’ll be setting out some of the finding of the paper listed at the bottom of this post. It is my hope that you can also understand how your cells and mitochondria, in particular, support your ability to adapt to stress and maintain wellbeing. I’m not a medic or biological scientist so reading the paper will give you much greater insight into the cellular basis of stress adaptability and mental health.
Mitochondria and physical energy
Energy is crucial for enabling our ability to adapt to stress and to maintain our performance levels. At the cellular level, energy is largely derived from mitochondria, which are present in every one of our trillions of cells. These transform the oxygen we breathe into energy, which is transported around the body for growth, healing and the ability to adapt to our ever changing environment.
The mitochondria make over 90% of the body’s energy in the form of adenosine triphosphate (ATP), the chemical basis for all reactions and metabolic processes. The body’s main consumers of energy are the brain, muscles, liver, kidneys, gastrointestinal tract, heart and lungs. Mitochondria also perform many other functions:
When it comes to handling stress, our mitochondria provide energy to our whole body/mind system to sustain components of the stress response. They produce and metabolise steroid hormones responsible in managing immune and inflammatory response and they work reciprocally with the neuroendocrine system and metabolic system. When mitochondrial function is manipulated experimentally, then we see altered physiological and behavioural responses to psychological stress, so the link is clear. In addition, the neural circuits regulating social behaviour and some mental health struggles such as depression are also influenced by mitochondrial function.
In all my years of psychological training I’ve never once heard mitochondria mentioned or been encouraged to think about the energetic requirements of stress adaptability and where this comes from. To know now that social behaviour, conditions such as ASD and ADHD as well as anxiety and depression are all affected by the energetic resource in our cells to support our functioning, is yet another helpful way to think about how we can help people recover and improve wellbeing.
Defining Stress
When defining stress a good general place to start is with any circumstance (real or imagined) which prompts the brain and body to adapt in order to maintain homeostasis. Maintaining the balance of body and mind requires energy. Most life sustaining biological functions require energy but the stress response is above and beyond any basic energetic needs we have, so the link between cellular energy consumption and stress management is an important one. Stress adaptability is resource intensive and western society and culture can be stressful in a way that we have lost sight of.
From Good Stress to Toxic Stress
First of all let me say that we all need some stress in order to grow, so it isn’t the enemy but let’s consider different types of stress.
1- “Good stress” happens when we take on a challenge that moves us towards a result we want or need, like interviewing for a job, or giving a talk before strangers, and feeling rewarded when one is successful. Here, stress mediators like cortisol and adrenalin promote adaptation during the challenge because they are turned on when needed and turned off when the challenge is over. We return to psychological and physical balance after the challenge is over.
2- “Tolerable stress” means that something bad happens that we don’t want, like losing a job, the end of a relationship, or the death of a loved one, but where the individual has the personal resources and support systems to “weather the storm” and be resilient. Stress mediators are turned on and may stay turned on or are repeatedly turned on and off to promote adaptation. By being chronically or repeatedly active, they may also promote potentially harmful processes leading to cardiovascular, immune and metabolic dysregulation and changes in brain circuits involved in emotional regulation (McEwen, 1998). However, the individual’s internal resources and external support systems minimise this aspect and eventually create a resolution that limits the long-term potentially pathological physical and emotional consequences.
3 – “Toxic stress” also means that something bad happens, like those events in “tolerable stress”, but where the individual lacks internal resources or external support systems, and, as a result, there is a lack of sense of control that leads to chronic physiological dysregulation that promotes harmful physiological changes and results in something called “allostatic load” and “overload”, described below. Lack of control has been one of the defining features of psychological stress that leads to disease (Cohen et al., 2007). As a result, when toxic stress situations are prolonged, mental and physical health disorders develop over time.
Stress and Allostatic Load/ Overlaod
The concept of “allostatic load” focuses on the paradox that the same mediators that help the body and brain adapt to stress can also cause mental and physical health problems when overused and become dysregulated. The individual’s bodily resources are key to promoting adaptation, performance and recovery from stressful circumstances (Sterling et al., 1988).
When allostatic mediators are not turned off or remain imbalanced, you get results like, too much or too little cortisol or an elevated or too low blood pressure. When dysregulation of these systems continues over weeks and months, we call it allostatic load, which refers to the wear and tear on the body that results from the chronic overuse and imbalance of the “mediators” (McEwen, 1998; McEwen and Stellar, 1993).
Allostatic load also then interacts with lifestyle factors and coping strategies including health-damaging behaviours such as unhealthy diet or a healthy but imbalanced diet, alcohol, smoking, inadequate sleep, lack of exercise, too much exercise, social isolation, the stress of low self esteem.
If the person experiences allostatic overload then this means that the mediators of the stress response eg the neuroendocrine, autonomic, metabolic and immune systems were unable to adequately cope with those circumstances in order to perform and recover well enough to be unharmed. The persons psychological experience of this might be anxiety, depression, dissociation, fatigue and overwhelm as well as a number of physical health problems.
Effects of psychological stressors on food- and energy-seeking behaviorus
Psychological stress triggers eating behaviour and shifts food preferences to denser calories, and shift fat storage to the intra-abdominal fat stores rather than stores closer to the skin surface because it is more easily accessible for energy usage.
There is a well established link between exposure to both acute and chronic stress with greater food seeking and food intake, particularly of comfort food (Masih et al., 2017; Adam and Epel, 2007). Previous day stress was associated with lower fat oxidation as well as higher insulin production (Kiecolt-Glaser et al., 2015), both physiological processes that favour “energy storage”.
Many studies indicate that stress and glucocorticoids (steroid hormones) in particular may lead to energy seeking and replenishment behaviour. This can help maintain allostatic balance and is an unconsciously body driven process for replenishing energy.
I find this fascinating because in psychology many assumptions exist about stress and food related behaviours being intended solely for self soothing and to down regulate stress. These studies however seem to be saying that the intention is to improve energy resources and resilience for handling stress.
Linking mitochondrial dysfunction to stress and physical and psychological illness
While testing the hypothesis that abnormal mitochondrial functions would alter responses to a psychological stressor, Picard and McEwen, 2018a found this to be true. They found that each mitochondrial defect generated a distinct whole-body stress response signature making an important link between stress adaptability and mitochondrial function.
Psychological or physical stress triggers neuroendocrine, inflammatory, metabolic, and transcriptional disturbances that ultimately predispose a person to disease via allostatic load/overload (Juster et al., 2010).
In the absence of real stressors and without the need to engage in physically demanding behavioural responses such as running away or fighting, stress hormones can dysregulate metabolism. In humans, individuals with higher circulating levels of cortisol under resting (non-stressed) conditions also have higher levels of glucose and triglycerides, and a higher score reflecting insulin resistance and a pre-diabetic state (Phillips et al., 1998). Those with higher levels of glucocorticoid can also become physically inactivity with depressive-like behaviour (Karatsoreos et al., 2010; Gourley and Taylor, 2009).
Conclusions
Overall the evidence suggests that mitochondria help us manage our physical and psychological reactions to stress by setting in motion the physiological mediators and energetic resource to adapt to the demands of the stress. It also highlights that our stress responses, when overused and overloaded may also contribute to translating stressful experiences into physical and psychological illness (Picard et al., 2014).
So, the question I am left with is, does the body or the mind reign supreme in our functioning? There is so much ‘messaging’ available that it is mindset and thoughts that affect our coping but perhaps it is time to put the body and physiological process at the forefront of stress adaptation. Or at least to consider that the two are inseparable and that problems in the mind and body reflect each other.
Based on the paper:
An energetic view of stress: Focus on mitochondria
Martin Picard, Bruce S McEwen d , Elissa S Epel e , and Carmen Sandi
Front Neuroendocrinol. 2018 Apr; 49: 72–85.
Published online 2018 Jan 12. doi: 10.1016/j.yfrne.2018.01.001