Science Interviews


Tue, 20th Sep 2016

Is mental illness a chemical imbalance?

Dr Kat Arney, The Naked Scientists

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This week Kat Arneyís been looking at a myth thatís all in the mind...Creative brains

Kat - Mental health problems are widespread in society, with around one in four people experiencing some kind of mental health problem, according to the charity MIND. These include depression, anxiety, post-traumatic stress disorder, eating disorders and more. Then there are other conditions such as schizophrenia and bipolar disorder.  But even more widespread than the incidence of mental health problems is the belief that mental illness is caused by an imbalance of chemicals in the brain, with an Australian survey finding that a staggering 86 per cent of adults believe this is the cause.

Whatís more, pharmaceutical companies that develop and sell treatments for conditions such as anxiety and depression have referred to the idea of Ďchemical imbalanceí in their marketing materials. But although itís a neat explanation for how things go wrong in the brain in mental illness - itís not really correct.

So where did the idea come from? It seems to date back to the 1950s, when some of the first drugs for mental illness came on the market. They had impressive effects on peopleís symptoms, and seemed to be boosting the levels of certain chemicals in the brain known as neurotransmitters. These are molecules that shuttle between nerve cells in the brain, sending messages and passing on signals. So the natural assumption was that if ramping up the levels of neurotransmitters fixed the problem, then the problem must be caused by having the wrong level to start with.

Unfortunately this isnít borne out in reality. For example, itís commonly believed that people with depression suffer from low levels of the so called Ďhappyí neurotransmitter serotonin. But research has discovered theyíre not particularly lacking in it. And two different drugs - one of which boosts serotonin, the other reduces it - can have similar effects on mental health symptoms. So clearly itís not that simple.

Itís tempting to try and pin everything on our biology, but it ignores the fact that the environment plays a big role, and people can take steps towards recovery. On the flip side, a recent German study suggested that people who believe in the chemical imbalance theory tend to have more negative reactions to people with depression than people who donít. Another test with people who had experienced depression showed that if they were given a spoof lab test suggesting that their serotonin was out of whack, they were more pessimistic about their chances of recovery and less confident of their ability to manage their depression. They were also more likely to shun psychotherapy in favour of taking prescription drugs.

So what do we know? Our brains arenít a set of chemical balancing scales, and lifeís just not that simple. Clearly, much more work does need to be done into understanding the causes of mental illness and how best to treat them, while avoiding stigmatising sufferers. And for the one in four of us that suffers from mental health problems, that canít come soon enough.


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