I have to admit something embarrassing. I am a registered psychologist working in private practice and I don't know what the term mental illness means. Well, on a general level I know that it refers to psychological problems, but I don't know exactly what is meant by the "illness" part.
As far as a I can tell, there are two possibilities. First, illness could be a metaphor. If a writer used a phrase like "terrorism is an illness of society," we would know that the author is using a metaphor because a society cannot literally be sick. It cannot get the flu or have a bacterial infection.
The second potential meaning of illness is literal -- there is actually a disease or sickness that affects the mental functioning of the person.
When we use the term mental illness, what do we mean? Are we using a metaphor, like the mind is not working properly, as if it was ill. Or, do we mean it literally that the brain is in some way sick?
This is not simply an issue of semantics and splitting hairs. There are consequences and implications to the language we use to describe problems, including how we conceptualize or think about the cause of the problem, and how we treat it.
When people speak of mental illness, it is common to speak of problems with the mind. But according to modern medicine and science, there is no "mind" per se. We have a brain and the neurons of that brain are responsible for our thinking, emotions, behaviour, and so forth. So, whenever we use the term mental illness or speak of the mind being unhealthy, we are really referring to the brain.
We are saying the brain is sick.
Given that the brain is an organ of the body, there are two significant implications of using the term illness to describe psychological problems.
First, there is an implication that the tissue and chemicals that make up the brain are either diseased (ex: virus or bacterial infections) or dysfunctional (the neurons are not firing properly).
Second, and following from the first implication, there is an assumption that medicine can be used to fix the ill brain. We use medicine to fix the other organs in the body, so why not the brain as well?
Hence, the term mental illness seems to lend itself more to the use of medication as an ideal and first line of treatment. And given that psychotropic medications (ex: antidepressants like Prozac) are among the most popular drugs in the world, it is fair to assume that medicine is indeed most people's first line of treatment.
But is the brain sick, and does the medicine fix this sickness?
The Biological Model of Mental Disorders
The treatment of mental illness has a long history of physical approaches, including lobotomy, electroconvulsive therapy, medication, and a variety of other such methods. Success has been variable.
As mentioned, the most popular approach is medication. The idea that medication might work rests on the chemical imbalance theory of mental illness, which proposes that chemicals in the brain are not functioning properly, causing problems like depression and anxiety.
The idea that mental illness, most notably depression, is caused by chemical imbalances is arguably the most widely disseminated theory of mental illness in existence. The theory is described on respectable internet sites, the mainstream media, professional organizations (ex: National Institute of Mental Health), and is used by innumerable health professionals.
The problem is that the research evidence for this theory is simply too weak. The problems with this theory have only really started to hit the mainstream media and the general population in the past five to 10 years. For example, multiple experts, including psychiatrists, have come forward to say that the chemical imbalance theory for depression is simply wrong. There is poor and inconsistent evidence that low serotonin causes depression.
Neuroscience has done a great job of finding correlations between mental disorders and various brain dysfunctions, but to date, no one has found a definitive biological cause for any one mental illness.
What Else Could There Be?
If biology doesn't explain mental health problems, what does (or could)? If thoughts and emotions occur because of neurons firing, then problems with neurons must underlie mental disorders right?
Not at all. Problems can arise when the brain is perfectly intact and operating with all chemicals in balance (whatever that might mean).
Imagine you touch a hot stove top. The pain will immediately force your hand to pull away quickly, which is an example of healthy reflexes.
Following this painful lesson, imagine that the stove has been turned off and you are asked to touch the stove top again. It is not hard to imagine being a little hesitant to touch it, even though you know it is no longer hot.
What is happening here? The brain has learned that the stove can cause pain and damage, and has produced a feeling of anxiety when around stoves as a precaution. This is the mark of a healthy, adaptive brain - one designed through evolution.
Now imagine that a child is bullied repeatedly at school. To prevent further bullying, they stay away from people and become mistrustful. Is this any less adaptive than pulling your hand away from the stove? Both serve to stop pain.
Now imagine that the child grows up and is very wary of other people and feels anxious in social situations. Like the stove example, they are generalizing from one period of time to another, in order to protect themselves.
In this latter example, does the person need to have chemical imbalances in their brain, or any other biological dysfunction to be anxious of other people? You might find that certain areas of the brain "light up" on an MRI when this person is in social situations, but this doesn't mean that dysfunction in these brain regions are causing the anxiety.
In fact, this person could meet criteria for depression and social anxiety disorder, and yet their brain is in no way dysfunctional or sick. If anything, their brain is operating the way we would expect it given the environmental circumstances, and the priority that evolution puts on self-protection.
Here we have a healthy brain (medically speaking) that is causing problems in the person's interpersonal life.
This person might need therapy to deal with the problem, but the root cause of the problem (bullying, mistrust, and avoidance) could never be solved by medication.
Should we say this person is mentally ill? Is their brain diseased in some measureable way?
Give it some thought. When you use the term mental illness, what do you mean?
Is it just a metaphor?
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