antidepressant debate

January 13, 2010

There has been a debate for some time about the effectiveness of antidepressant medications, which are commonly used for anxiety and depression in routine psychiatric practice. A recent study published in the JAMA has reignited this debate, as it seems to indicate that there is little difference between antidepressants and placebo, for mild to moderate depression. In this large-scale randomised controlled trial patients with severe forms of depression benefited greatly from antidepressants when compared to placebo. Patients with mild to moderate depression seemed to respond both to antidepressants and to placebo.

This was discussed in depth at the Carlat Psychiatry Blog (written by a psychiatrist) It has been known for some time that the placebo response is powerful when it comes to depression and anxiety. This may indicate that these conditions naturally resolve with time, or perhaps it means that the power of belief has a very strong effect on mood – something we intuitively know to be true.

For psychiatrists, the question is whether or not we should prescribe antidepressants for the less serious forms of depression, and this is even more pertinent for GP’s who see the majority of such patients. It has been suggested that we should prescribe sugar pills for depression as the placebo response is so strong and this would benefit the patient without causing any side effects.

The majority of newer antidepressants have minimal side effects for the majority of patients. However there is a worrying trend towards increased suicidal thoughts in a small number of people, particularly adolescents. In practice antidepressant-induced suicide is virtually never seen, but this tends to show up in very large research trials.

I think this study also has implications for natural and alternative therapies, which are very popular but generally quite expensive for patients. We know that the placebo response is very strong, and so we can assume that the benefits of natural therapies are at least partly due to placebo response. Natural therapies are beneficial because they encourage healthy living and may assist mood in that way. It may be useful to bear in mind the placebo effect when considering the more costly therapies and may be advisable to seek a cheaper option!


Extra post for today, since I missed yesterday’s post. Putting sex in the title is sure to attract more visitors.

Today  someone sent me this article – new antidepressant increases sex drive – about a new antidepressant called flibanserin. The article refers to the drug as a “female Viagra” but really it’s nothing like Viagra at all (which affects blood circulation) but works on the brain in a similar way to other antidepressants.

The aphrodisiac properties of the medication were discovered by accident, at the end of a research trial. Basically, women tried on this drug were doing everything they could to hold onto it at the end of the trial, so someone started asking the questions.

It seems funny to me that many of our major medical breakthroughs were discovered by accident. Penicillin is the obvious one, but also lithium for Bipolar disorder – I just can’t think of any others, but feel free to leave a comment if you know one.

Anyone who is familiar with our common antidepressants will know that they often cause problems with libido. The patient is sometimes left with a choice of being depressed, or having no sex life – a really fun choice, at that. I imagine this drug will be one to watch when it is finally released, which may be several years in Australia at least.

Another interesting antidepressant to watch is agomelatine, a melatonin agonist. Melatonin is an important hormone in regulating our sleep-wake cycle and insomnia is a huge feature (cause and effect) of depression. So this one will be an interesting drug for the treatment of depression and insomnia. It’s already available in the UK but not Australia or the USA.