What Causes Mental Illness?

As psychiatrists we are taught the biopsychosocial model for the cause of mental illnesses. Note that this is written as one word, which is intended to indicate the unity of each of these aspects. As Christians we would include spiritual as a forth aspect of the model.

When approaching mental illnesses, one major reason for the stigma often associated with them is that we often have a Greek, dualistic approach to thinking about ourselves, and about illness. Thus, in a gross oversimplification that is not biblical at all, we think of our bodies as a mere container for our true selves, our spirits. Frank Viola quite rightly rejected this separatist view in a recent post. But all too often, we think of our minds as totally separate from our bodies. Thus a mental illness can erroneously be constructed as not a “true” illness at all, but rather a disorder of the psyche which we may see either as our mind, soul, or spirit.

The Bible has a much more holistic view of our makeup. It understands that God made us as a being that relates to him, that relates to others, and that is very much integrated with our bodies.

It is true that mental illnesses so far do not have a blood test or brain scan that can help us identify them. Having said that, there are a number of avenues of research ongoing that may lead to such tests in the future. Patterns of activation in our brains in response to faces that display different emotions is one such avenue.There is a lot of evidence for physical abnormalities seen in some mental illnesses.

Reduced activity of the thyroid gland can lead to depression, and increased thyroxine can mimic mania. People who have experienced the remarkable way giving thyroxine “wakes” them up will never again think that the brain is disconnected from the rest of the body.

Some will simplistically say mental illness is about “chemical imbalance” in the brain. In fact, most psychiatric medications target the level of activation of various brain circuits of neurons. Thus, psychosis is associated with increased activity in certain neurons in the brain that use dopamine as a neurotransmitter. These neurons fire too often. So far every antipsychotic medication that has been licensed works by blocking dopamine receptors, and reducing the firing of those neurons.

Similar changes are seen in different neuronal circuits in depression, where the goal of medication is to increase the level of serotonin and/or noradrenaline.

However, to say that the illnesses are caused by these abnormalities is probably a stretch too far. There are other neural circuits involved in these conditions, and medications are being tested that target different receptors in the brain. It may be that raised dopamine activity and lowered serotonin activity are signs of an underlying problem rather than the actual cause.

We also see remarkable support for the fact that brain abnormalities can affect our emotional state, and behavior by what we observe when different parts of the brain are damaged by strokes or cancer.

Further evidence for the physical nature of mental illnesses is that they run in families, and are more common in twins who are identical than twins who are not. Even when twins are raised in different families these differences persist. It is not the case, however, that we simply inherit a mental illness. Environmental factors do play a part.

The evidence supports the idea that we can inherit a predisposition to mental illness, rather than the illness itself. What determines whether you actually get the illness is not always known. There may be some physical reasons that trigger the illness actually coming on, one that is controversial but appears to be correct is cannabis use. So, millions of teens use cannabis with no apparent ill effects, but some of them seem to be triggered into a psychiatric illness. Once that trigger has occurred, the illness might still appear and disappear without the need for that trigger, however.

There is a lot of evidence, however, that the triggers need not be physical. Psychological causes seem to play a part. It really is important what we fill our minds with. If we constantly harbor negative thinking patterns, we should not be surprised if eventually a tipping point is reached, and we are no longer able to pull ourselves out of the negative thinking. Thus, someone who is told they are “useless” constantly may eventually internalize that belief, and eventually a full-blown depression might result.

A very good example of how things that we think about can affect our mood, is the almost universal response to bereavement. We all get depressed, at least for a while, when we loose someone we love. Just as we may cry when we are saying goodbye to a loved one who is emigrating, our smile and jump for joy when they return. In fact, most of us can improve our mood by thinking of a pleasant memory or a good joke, or we can make ourselves feel sad by thinking of a tragedy. In depression our ability to influence our mood can become much less, and it can feel like too much effort to “think happy thoughts,” and that itself is part of the illness.

If we loose a job, or we loose our sense of value, we are not just affecting how we think, we are affecting our social selves. There is no question that mental illness can also be triggered by social aspects, whether it be the quality of our relationships, or our sense of contributing to society. How we are getting on at work, in particular our relationship with our boss can have a massive effect on our mental health. Marriage is strongly protective of mental health, but a sick marriage makes us miserable. Patients with mental illness often struggle to forge relationships that can be protective. One of the cruel things about stigma, is that it can maintain the problem that gave rise to it.

Clearly, there is also a long history of Christians reporting how their relationship with God can make them feel guilty at times, and at other times can fill them with great joy in forgiveness.

It is my view that when faced with an individual with mental illness, we should not seek for a single cause, but rather recognise a combination of biological, psychological, social, and spiritual causes may have given rise to the condition. When it comes to treatment, we should also target each of these areas for the best effect.