Depression #3 - What causes depression, and what is happening in the brain?

In this, the 3rd of our 4 post series on depression by Dr Stephanie Hughes, we discuss how people slip in to depression in the first place and what factors make some people more prone to depression than others. We further explore what science knows about  the chemical changes that happen in the brain of a depressed person. 

Why do People get Depression?
There is no single cause for depression; many factors can combine to trigger a bout –

  • stressful life events such as bereavement, divorce, redundancy or a house move can cause people to experience depression. Ill health, money worries and relationship problems can also be implicated.
  • Sadly, we know that people with lower incomes and in less ideal social circumstances are more prone to depression, as are older people.
  • Alcohol and drugs are absolutely terrible for causing depression, but people often use them to try to feel better if they are already feeling a bit down – this is a recipe for disaster as it will actually make them feel a whole lot worse!
  • You’re more likely to suffer from depression if someone in your close family has been depressed, and it’s probably not just genetic factors at work here (although there is little doubt that genes directly affect individuals’ ability to process some chemical signals in the brain) –
  • There is evidence to suggest that upbringing, your self-esteem levels and certain other aspects of your personality will combine to determine your likelihood of depression. Perfectionists, for example, have a tendency to depression because they and their lives are constantly failing to meet their own impossibly high standards. People who have had unhappy childhoods, or who have experienced abuse, are more likely to suffer from depression.
  • There are certain medical conditions which are themselves directly linked to depression, such as an underactive thyroid gland; and many commonly prescribed medications, such as blood pressure- and cholesterol-lowering agents, have depression as a significant side effect.

Post Natal Depression
Women who have just given birth may experience a special sort of depression – post-natal depression (PND) – which results from the combination of the hormonal and physical changes associated with birth, as well as the profound psychological effects of being responsible for the life and wellbeing of another human being. Post-natal depression is particularly serious and distressing as, sometimes, the new baby suffers as well as the mother, if mum is not feeling well enough to take care of her child properly (or, in very rare cases, seeks to harm her child). Doctors, midwives and the whole healthcare team try their best to be on the sharp lookout for signs of PND in new mums, but inevitably some patients do not receive the care they need. Similarly, hormonal changes associated with the menopause can lead to lowering of mood.

Depression in carers
It has already been mentioned that long-standing pain, illness or disability can lead to depression; it’s also important to recognise that the stress that carers experience can also lead to depression – the daily responsibility of looking after another person can be very draining of physical and emotional reserves, and carers often put their own needs way below everyone else’s.

Seasonal Affective Disorder (SAD)
Some individuals experience a definite dip in their mood in the winter – this is known as Seasonal Affective Disorder (SAD) and is due to the effects that low levels of sunlight can have on the brains of susceptible people; believe it or not, the low levels of sunlight in the winter months can directly affect the production of serotonin (the “happy hormone” discussed in more detail later) as well as playing havoc with the body’s internal clock; both of these can combine to cause depression. It’s possible that the normal reduction in social interaction in the winter also has a part to play – individuals who are isolated and shut off from contact with others, either through their work or their social circumstances, have a much higher risk of depression.

Loneliness & Isolation
A new sort of depression, so-called “Facebook Depression” is now being talked about, whereby individuals spend large amounts of time in virtual relationships on-line, but lack real human social interaction and experience a lowering of mood as a result. Bear in mind that, for some elderly people who live alone in the UK, it is not uncommon to spend weeks at a time without having a conversation with another person.

Work related stress
Work-related stress is a massive problem in the UK, and can directly contribute towards the development of depression. Common problems might include unreasonable workload pressures, or feeling bullied or undervalued at work. As previously mentioned, the symptoms of depression can include poor concentration and energy levels, and it’s easy to see how these could be misinterpreted as poor performance at work – disapproval or disciplinary action will inevitably lead to the depressed person feeling even worse, and so a vicious downward spiral begins. This can lead to the person being simply unable to work at all and having to go off sick, or, even more tragically, it can lead to the depressed person continuing to work when their symptoms mean that they really aren’t well enough to (and are even putting others or themselves at risk). Employers have a legal obligation under the Health and Safety at Work Act (1974) and the Management of Health and Safety at Work Regulations (1999) to minimise the risk of stress-related illness to their employees. If you feel that your job is making you ill, speak up and tell your manager about it.

Depression at a chemical and physical level
Having seen that any type of stress can lead to depression, what actually happens inside the brain of a depressed person? State-of-the-art medical imaging technology now allows us to “see” directly inside the living brain, and there is no doubt that depressed people’s brains are structurally different from those of non-depressed individuals, with certain key structures, such as the hippocampus (the area concerned with memory and emotions) being appreciably smaller. There has long been an understanding that neurotransmitter chemicals in the brain, such as serotonin (the so-called “happy hormone”), noradrenaline and dopamine, have important roles to play in depression, but the exact nature of these is not fully understood. It seems that depression occurs as a result of a complex interplay between chemical and structural changes in the brain, as well as the way in which it functions to send messages via its nerve cell connections. More research is needed. Observations implicating neurotransmitter deficiency in depression led to the development of many of our most commonly used antidepressant medications.

Now go to our 4th and final blog post, which will explore these antidepressant medications in more detail, along with other treatment methods and lifestyle changes that help to get sufferers of depression back on the road to recovery.