Question: When someone suffers with anxiety and it isn't down to 'environmental conditioning' what are the chemical imbalances in the brain that people talk about? Additionally, what are your views on relying on medications like antidepressants (such that one becomes dependent) to cope?

Susan Cartwright answered on 19 Jun 2015:

The human brain contains about 100 billion brain cells, or neurons. These neurons are vaguely tree-shaped, with lots of branches coming out of the main cell body and spreading out towards other neurons. There are two types of branches, the dendrites, which receive signals from other neurons, and the axon, which transmits signals. However, although they come close together, one neuron’s axon never actually touches another neuron’s dendrite: there is a small gap between them, called a synapse. Signals cross this gap either by electricity or with the aid of chemicals called neurotransmitters: electrical synapses are faster, and are used in cases where quick response is the key factor, but chemical synapses are more versatile.

The chemical imbalances in the brain that are implicated in mood disorders like anxiety and depression are imbalances in the concentrations of these neurotransmitters. Unfortunately, there are many many different neurotransmitters, and we are only starting to understand what they all do. But the main ones that seem to be implicated in mood disorders are serotonin, noradrenaline and dopamine. Low serotonin levels are particularly associated with depression, and many modern antidepressants are SSRIs – “selective serotonin reuptake inhibitors”. These increase the concentration of serotonin by blocking its reabsorption by the neuron after use, thereby making it available for reuse by nearby neurons. SSRIs are used to treat anxiety, panic attacks and OCD as well as depression.

Like most drug treatments for chronic disorders, SSRIs for depression have pros and cons. The first and most important pro is that they are very effective for many people, especially when combined with more traditional “talking cures” such as cognitive behaviour therapy, and although they do have side effects these are less severe than older types of antidepressant. Studies indicate that about 60% of sufferers from severe depression improve when given SSRIs, which is about double the number who improve when given a placebo or sugar pill – so they really do work. However, generally doctors try to avoid prescribing SSRIs to young people, because – somewhat paradoxically – they are sometimes associated with suicidal thoughts or a wish to self-harm. This is obviously deeply undesirable – though clearly it’s not a common side-effect (an antidepressant that made people feel suicidal would be about as useless a drug as one can think of!).

My view is that antidepressants are an important tool in dealing with depression, but their use should be carefully monitored by the patient’s medical team to ensure that any side-effects are picked up, and that if the patient is among the 40% who don’t benefit, they aren’t left taking the drug to no purpose (there are other antidepressants, such as SNRIs, serotonin-noradrenaline reuptake inhibitors, which may work on people who don’t respond to SSRIs). And one shouldn’t usually go on taking them for years and years – a typical course is six months, or up to two years if you’ve had previous depressive episodes. Obviously, if there is some clear external reason for the depression – for example, divorce, or the death of a relative or friend – it’s important to address this problem with counselling or similar, so that the patient can come off antidepressants because the cause of the depression is being dealt with. But some people have depressive episodes for no good reason, and if antidepressants help them, I don’t see a good reason not to take them. There are risks associated with long-term use – there is a possible link with type 2 diabetes – but depression is a miserable illness, so you have to strike a balance.

[Please note: I am not a physician. This is the best information I can come up with, but it’s not a professional assessment.]