Why Depression Happens

In this article I’d like to explain a way of looking at and understanding depression which has just been published and which I feel pulls together a lot of what we know about depression from the fields of genetics, neurochemistry, neuroscience, behavioural psychology and social psychology.  I think that, if you can understand where depression might come from and why it happens, it may help you find a way out of it.

Brief summary
Depression is the body adapting in order to conserve energy after we perceive that we’ve lost out on something important like a relationship, something which forms part of our identity (like a job) or a personal asset (such as our home, health or mobility) after we’ve invested in it. It does this, because from an evolutionary perspective, if we conserve energy then we are more likely to survive.
Below, I explain in more detail how this comes about and how it might help us to understand depression from this angle.

Some things can pre-dispose us to depression as follows:
Traumatic Experiences
If we’ve had early traumatic experiences – i.e. loss of a parent, abuse or a difficult childhood it an affect our brain’s development, affecting learning and memory areas of the brain which in turn makes us more vulnerable to depression.

Genetics can play a part too. If we carry the 5-HTTPLR genetic variant (linked with serotonin which helps us maintain a good mood) or some variants of the FKBP5 gene or the BDNF gene we are more likely to experience depression following a stressful life event.  Ultimately, if our family had depression, we are more likely to develop it.

Negative Thinking Biases
Whilst we know that people who are depressed tend to notice negative information more than others, they are more sensitive to negative feedback, and remember negative information more readily, we often think it’s a symptom of depression, but actually, it may be the reverse.  If our brain works in these more biased ways, we are actually more prone to depression. This might be because certain parts of the brain simply function differently.  It might also be because the genetics we talked about above are in some way impacting on the way we process information.  Equally, the childhood trauma we spoke about may impact on these processing abilities too.

Body Sensitivity
In addition, the way our body reacts to stress may have an effect on our susceptibility to depression. If our stress regulation system (the HPA) is out of balance, then we are more prone to depression.  We’ve found that stress hormone levels are higher in depressed people when they are exposed to stressful situations.  This may even cause cells in our brain to die off which in turn can impact on the way we think and remembers things and again makes our stress reaction in the HPA even more out of balance.  The part of the brain which processes emotion (the amygdala) is activated to a higher level in individuals with both the gene variations which we spoke of earlier, and those with childhood trauma, meaning that the stress response is higher and thus linked to depression in these individuals.  This hyper-activated emotional processing means we remember things in a biased way and our emotions are more unstable too.

Low Self Esteem

The way we develop can influence our predisposition too.  If at an early age we develop low self-esteem, or develop a tendency for our self-esteem to drop when things go badly, then this can predict depression later on in life.  People with depression also tend to blame themselves and predict that things go badly and these negative beliefs keep the cycle of depression going.

If we’re predisposed however, we normally still need something to trigger off this depression.  This theory suggests that the trigger is when we think we’ve lost something in which we’ve invested resources. This might be rejection by a lover, death of a child, and decline in productivity at work. It doesn’t have to be a singular event though, it can be a gradual build up in say, stress at work.

Depressive Belief
However, the important thing to recognise is that the things which trigger depression only have an effect when we think that we have no control over them and believe it’s irreversible.  This negative appraisal of the situation is key.
Over time, if we’re experiencing more and more stress, unfortunately we develop a lower and lower tolerance of stressful situations, because our brain is trying to protect us from the same again, so it becomes more sensitive.  Our brain has developed a ‘depressive belief’ or attitude to these situations and so small events re-ignite the distress we felt at previous situations; it then tries to solve it with depression.
How predisposition + trigger + despressive belief  = depression
So, some of us might have a pre-disposition and there may be a trigger as well as a despressive belief too.  But why does that bring on all the symptoms of depression?

How we survive
Three systems within our personality help us work towards survival – they are our emotions, our behaviours and our cognitive systems.
Our behavioural system ensures that we do things which meet our needs, our urges and cravings.
Our emotional system provides the positive and negative reinforcement which gives us feedback along the way of how we’re doing.
The cognitive system – our thoughts – is in control, coordinating the other two.

In depression we can end up doing less, thinking negatively and feeling emotionally low, sad, flat, so how does this help towards survival?  We can understand how below.

Conserving energy
Depression can be understood as a means of conserving energy.
For example, relationships allow us to achieve the evolutionary goal of survival because being in a couple gives us more protection and security, is likely to mean more resources because two people are providing an income, food, skills, resources and support.  So when a relationship stops or gets bad,  we feel the need to compensate for this loss of resources by stopping or the limiting activity which doesn’t help us survive. So we are programmed to reduce libido (because we don’t need another mouth to feed), appetite (if I eat less then I can save food for later and it will last longer),  sleep too much (to replenish energy)  and even reduce parenting skills (I need to survive, not others).
In a similar way, we can sometimes react to environmental turns for the worse such as winter weather because we see it as there being fewer resources and thus we need to spend less energy and do less.
The problem comes from the fact that this response was more useful previously, when lack of resources really would endanger our lives, and now, this isn’t the case; our depressive response might be a bit excessive. It depends on whether you’re experiencing mild or severe symptoms.
Social withdrawal, slow movements and slowing down or simplifying the way we think also help our energy conservation. This might also be the reason why we have less enjoyment when we’re feeling depressed, because our body decides to reduce the reward (or pleasure) were receive when expending energy in an aim to discourage us from doing things which will expend energy.

Maintaining Vigilance
Keeping our guard up is important for survival as we can pre-empt any threats which might endanger us.  The areas of the brain which do this are more active in depression.  Feeling restless, difficulty concentrating and insomnia may have all developed to increase our ability to notice danger, in the same way that anxiety and irritability may work – they aim to protect us from danger. Equally, social withdrawal may also help us avoid risks.

In Summary
Depression is activated by a combination of an external event and a ‘perceived loss of a vital investment’. If the individual is predisposed then there is even more likelihood that they will develop more severe adaptations and thus symptoms.
If we think of depression in evolutionary terms it acts by mobilising the behavioural, emotional and thought systems of our personality. Stress alone doesn’t make this happen but a stressful event plus a depressive belief often make us appraise a situation negatively. Thus when we think that we’ve lost something vital in which we’ve invested resources (time, effort, vulnerability) the evolutionary depressive system kicks in to help us conserve energy.
The extent to which it occurs depends on how much we feel we’ve lost. This depressive reaction can be helpful, but if we have developed feelings of hopelessness or helplessness alongside this, then the depression can become unhelpful and thus we experience severe symptoms.

There is Hope
Whilst we can’t change our genetic makeup, or our childhood, or sometimes even the stressful events themselves, there are ways forward.
Medication can of course impact on the chemical imbalance regarding serotonin, cortisol, adrenalin and other hormones for some. But the fact that this ‘depressive belief’ is part of the formula for depression is what can help us.
Ultimately, this conservation of energy (or depression) has been influenced by the way we think about a stressful situation.
We know that when our beliefs change back again the depressive response stops and this change in perspective can happen spontaneously or with our own effort.
Because this is often hard (because some of us may have had years of thinking in these depressive ways) that is where therapies can help; by helping you challenge these long-standing beliefs and attitudes and helping to re-train your brain out of the negative bias, and into a more balanced way of looking at things.

Taken from:
Beck, A. T., & Bredemeier, K. (2016). A unified model of depression integrating clinical, cognitive, biological, and evolutionary perspectives.Clinical Psychological Science, 2167702616628523.
Full article here: http://cpx.sagepub.com/content/early/2016/03/26/2167702616628523.abstract

www.happii.uk is a website providing information about mental health and wellbeing. Happii.uk is provided by Anna Batho, a therapist working in High Wycombe and providing therapy in Amersham and the wider Buckinghamshire (Bucks) region.
You can contact her here.

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