杏吧原创

Antidepressants really do work, and should be prescribed to millions more people, if you believe today鈥檚 newspaper headlines. The reality is more nuanced, as we still don鈥檛 know that these drugs will help most people with less severe depression.

The positive press has been triggered by a study out this week that found these medicines do relieve depression, contradicting previous claims they are little better than a placebo.

The was a mammoth undertaking by a respected group of researchers. It reviewed over 500 trials of 21 different drugs, containing more than 100,000 people with depression. Most media reports say the new findings should put the controversy to bed.

Let鈥檚 not be too hasty. The previous negative studies found that antidepressants don鈥檛 work in people with mild-to-moderate depression. Most of the people in the latest review had more severe depression. So it is good news for that severe group, but it doesn鈥檛 resolve whether this is true for all forms of depression.

Side effects

Mild depression is more common than the severe form, so we are still in the dark about how much antidepressants help most people 鈥� and the main complaint is that doctors prescribe these pills too easily for those at the milder end of the spectrum. Nor does the new study reveal how well they work for the other conditions they are often recommended for, such as anxiety and phobias.

Ineffectiveness is only one of the criticisms. Another is that people aren鈥檛 properly warned about possible side effects, ranging from loss of libido to disabling anxiety and agitation. Most alarmingly, there are even concerns antidepressants can trigger .

Do the benefits of antidepressants outweigh the harms? The latest study says yes, because for most of the 21 medicines, drop-out rates were no higher in those taking the drugs than in those taking a placebo, suggesting people felt the benefits were worth any side effects, say the authors.

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There is a problem, however. Studies that analyse past trials, as this one does, can only be as good as the numbers fed in. Experience has shown that pharmaceutical firms can slice and dice their data to make the results look better than they really are.

For example, a 2001 study of the antidepressant paroxetine, which wasn鈥檛 included in this recent review, showed similar side-effect rates in those taking the drug and a placebo. When independent researchers got their hands on all the data in 2015, however, they found paroxetine was linked with more self-harm and threats of suicide.

Withdrawal symptoms

Another concern is that some people find it hard to stop taking antidepressants without crippling withdrawal symptoms. Standard advice is to reduce levels gradually, but the pills aren鈥檛 always manufactured in low enough doses. The latest study didn鈥檛 address this either.

How can there be so many questions over such a widely used group of medicines? One source of confusion is that antidepressants affect everyone differently. One of their most consistent psychological effects is described as a blunting of emotions. Some people hate that and say they feel like a zombie. Others find it helps relieve their low moods. There is a similarly mixed experience of the side effects.

Such diverse reactions might explain why the popular debate can be so polarised. Arguments against antidepressants can verge on an ideological opposition to medical help 鈥� a dangerous stance when they can be a life-saver. On the other hand, some proponents say they are as crucial for treating depression as insulin is for people with diabetes. Yet the idea that antidepressants work by topping up a 鈥渃hemical imbalance鈥� of the brain signalling-molecule serotonin has been largely discredited.

If you have a personal stake in these questions, it must be frustrating that almost every month the pendulum of opinion seems to swing back and forth. As is often the case in science, the reality may lie somewhere in between.

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