There are three different types of stress. Are you in control?

Summary: there are three main types of stress. Also, the brain triggers the release of stress hormones, such as cortisol, and reallocates energy to ensure survival. However, psychological stress can have a long-term devastating effect on the body and the mind.   

Introduction

There is more than one type of stress and each one affects you in different ways. For a general definition of stress I encourage you to read my previous post: what is stress?.

Let’s go straight to the point. There are three types of stress:

1) Acute stress – an extremely stressful event that demands an immediate physiological adaptation to ensure survival (e.g. a person jumping to avoid getting hit by a car when crossing a street or an antelope sprinting from a hungry lion in a savanna).

2) Chronic stress – a prolonged period of pressure in which an individual has no control over the situation (e.g. a farmer with less food caused by a drought that devastated his crops).

3) Psychological stress – a sustained emotional perception that generates a feeling of anxiety or discomfort towards life events (e.g. parents divorce, death in the family, made redundant at work) or social disruptions (e.g. long and busy commutes, poor working conditions, beginning or end of relationships).

The good news is that the body can reasonably withstand adaptation for short-term emergencies, i.e. acute and chronic stress. The bad news, though, is that psychological stress creates detrimental effects on your body and mental health; it might start as flu or a bit of anxiety and depression symptoms. Ultimately, psychological stress could lead to ulcers and even cancer [1].

What happens in the body during a stress-response?

Both dwelling on a failed relationship and being chased by a lion can trigger the rapid mobilisation of energy from storage sites (e.g. fat cells, liver, muscles) and the inhibition of further storage [1]— a hallmark of stress-response. So, what does this mean?

Cortisol, a steroid hormone produced in the adrenal glands located on top of the kidneys, is released as a short-term adaptive solution to mobilise energy reserves (e.g. glycogen) Once there is enough energy converted into glucose, critical muscles (e.g. the legs to enable running form any threat) receive it as quickly as possible. The mobilisation process receives additional support by an increase in heart rate, blood pressure and breathing rate, all of which circulate nutrients and oxygen. So far, so good, right?

However, remember that the brain controls the allostatic mechanism and does not distinguish what sort of emergency the body goes through (why? read here). The brain assumes there is a threat and reallocates its energy accordingly. In other words, whichever area or organ is vital to keep you alive (at that very moment) will receive energy; otherwise, it will have to wait until there is no more threat. Psychological stressors, however, might take a long time to go away.

Therefore, the brain maintains a state of emergency and halts most long-term and energetically expensive body functions. For example, during stress, there is reduced tissue repair and no digestive process available. Imagine a stranger attacking you. There is no need to have your digestive system functioning as if you were about to have lunch. Honestly? What you want is energy redirected to your legs so you can run away as quick as possible. These shifts also explain why in emergency situations your vision gets heightened, whereas your bowel movements may hint you need to go to the bathroom—immediately!

Likewise, the sexual drive undergoes some changes (e.g. females are less likely to ovulate, whereas males have difficulty with erection). The bottom line shows there is nothing more important than survival, and psychological stress creates unrealistic threats for long periods.

Exercise

What is your weekly routine? Make a list of potential psychological stressors affecting you. How long have theses stressors been around? Have you noticed any symptoms of anxiety, such as excessive worry and difficulty to sleep?

Conclusion

Stress is a complex topic and has been negatively affecting many people’s physiology and mental health. It is a crucial survival mechanism linked to the brain, which controls the allostatic balance and will do whatever it is necessary to keep you alive. However, psychological stressors may extend for long periods and eventually affect essential body functions. The brain continually prioritises and reallocates energy to ensure survival. Similarly, if you unexpectedly lost your job, then you would save money for food and mortgage, rather than spending on a fancy dinner (presumably!).

Reference

[1] Sapolsky, R. M. (2004). Why zebras don’t get ulcers.

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Your response to stress may lead to depression — a gene vs environment analysis.

Summary: genetics and environment are not mutually exclusive in conferring risk factors for depression; the answer may come from the interplay between the two variables in your response to stress.

Introduction

Depression is a disabling mental illness. According to the Diagnostic and Statistical Manual of Mental Disorders (5th edition), the most common symptoms of depression are sadness, fatigue and anhedonia (i.e. the inability to feel pleasure in pleasurable activities).

Moreover, depression profoundly interferes with a person’s life. It impairs the ability to function at school during childhood and in society during adulthood. In its severest form, depression can lead to suicide [1]. Globally, depression represents a public health challenge affecting over 300 million people, and by 2030, it will be the most significant cause of disability in the world (World Health Organization, 2017).

There is an urgent need to raise awareness as well as to educate people about the potential reasons leading to depression. One example is the response to stress (i.e. how your body physiologically reacts to a stressor), which receives influence from the interplay between genes and environment. Nevertheless, there are still one-sided arguments out there.

The social argument

 A researcher called David Buss designed a correlational study between participants’ self-report (i.e. what people say) and behavioural measures (i.e. what people do). He wanted to analyse mate selection (i.e. how people choose their partners). Buss reported a positive correlation between the two factors, which indicates that personality is often consistent with behaviour [2].  

Why is this relevant to stress and depression? If personality correlates with behaviour, then people who consistently live in a stressful environment and present sad mood are potentially depressed. In his study, Buss describes three mechanisms driving the positive correlation between personality and behaviour, which you may identify in people with depression:

  • Selection. The deliberate choice and gathering between similar people as well as avoiding those who are different (e.g. depressive individuals are more likely to seek depressive-like individuals). The selection mechanism also applies to the environment (e.g. depressive individuals are more likely to avoid energetic places, such as a party).
  • Evocation. This mechanism refers to individuals who unintentionally elicit specific behaviour from others. (e.g. depressive children evoke more attention from their parents; whereas active children evoke a strict parental control).
  • Manipulation. The unaware modification of surrounding environments to address one’s personality (e.g. depressive individuals may decorate their homes and workplace with darker colours).

These mechanisms and patterns seem obvious, but most of us are unable to notice them. Moreover, social studies that attempt to address biology-based disorder must be interpreted with caution. The combination of the three mechanisms do not offer certainty; it only increases the likelihood of developing depression. Correlation does not mean causation.

Therefore, social arguments alone are unlikely to provide a reliable and valid answer. One-sided analysis struggle to report normative measures enabling clinical treatment of depression (e.g. cognitive behavioural therapy). As a consequence, correlational studies are more likely to maintain the status quo, rather than providing a solution.

The interplay with genetics

Gene-environment interaction is the link between two variables arising from the effects of one variable changing conditional to the other.

Let me unpack this for you.

The interaction between your genes and the environment occurs when genetic factors influence the body’s responses to the environment (or whatever happens around you). The environment cannot directly alter gene sequences. However, genetic effects, such as the ability to cope with stress, are dependent on gene expression [3]. For example, the fight or flight response varies from one person to another.

Two factors influence gene-environment interaction:

  • Spontaneous mutations. Each person inherits 50% of genes from her mother and 50% from her father. However, along the process, there are genetic mutations that make you different from your parents. These include changes which you cannot ‘see’, such as the production level of gonadal hormones under a stressful state. So, let’s get used to thinking beyond ‘eye colour’.
  • Population changes. The changes in the frequency of a gene in a population. For example, a native tribe living in a remote location with no external interference is more likely to maintain similar characteristics. In this case, it creates a genetic bottleneck and some diseases never disappear from a population. Conversely, in a metropolis like London, there is more genetic variation.

Therefore, the environment you live in can relatively interfere with your genetics expression, mainly through your ability to cope and respond to stress.

Genetic triggers

King’s College London researcher Robert Plomin reports that the environment accounts for over 50% of the population variance of depression [4]. Thus, changes in the environment play a significant role in heritability compared to the role of genetic mutation alone. Below are some elements that affect your stress-response and increases the chances of depression:

  • Risk factors. Social and Economic Status triggers a stress response (e.g. worry and anxiety).
  • Social interaction. Parenting style, loneliness or a poor workplace environment.

In other words, it is likely that a person with a negative genetic predisposition to stressful reactions become depressed living in a hectic and chaotic environment. So, taking some time to identify stressful triggers in your environment as well as particular behavioural patterns may prevent mental illnesses, such as depression.

Despite the efforts to understand the overall scenario conferring risk of depression, one-sided analysis is not an effective way to solve the problem. Instead, an individual analysis would be far more effective. The interplay between genetics and environment is an insightful source of information. Your stress-response to the environment you live might be a key player in developing depression.

References:

[1] Gunnell, D., Kidger, J., & Elvidge, H. (2018). Adolescent mental health in crisis.

[2] Buss, D. M. (1987). Selection, evocation, and manipulation. Journal of personality and social psychology, 53(6), 1214.

[3] Rutter, M. (2010). Gene-environment interplay. Depress Anxiety, 27(1), 1-4.

[4] Plomin, R., DeFries, J. C., Craig, I. W., & McGuffin, P. (2003). Behavioral genetics. American Psychological Association.

Lau, J. Y. F., & Eley, T. C. (2010). The Genetics of Mood Disorders. Ann Rev Clin Psychol, 6, 313-337.

World Health Organization (2017). Depression and other common mental disorders: global health estimates.

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