Drugs to treat low mood may not be a silver bullet, but they still work

Up to one in seven of us will experience depression during our lives. Different people experience different symptoms of depression. While many people experience a mild episode, depression remains a leading global cause of morbidity. Sadly, depression can be potentially life-threatening, for some because of an increased risk of suicide. Existing treatments, including several types of antidepressant medicines and psychotherapies (talking therapies), are effective, safe and not addictive.

However, beneficial treatment effects can take weeks to build up and each treatment does not work for everyone. It is therefore essential that we understand what happens in our brains when we experience depression so that treatments can be improved and targeted.

In the middle of the 20th century, the theory that depression was caused by a chemical imbalance in serotonin represented a really important step forward in the history of medicine. Since then, there is a huge of amount of research that tells us that the brain’s serotonin system plays a very important role in how our brains process emotions. As depression involves changes in how our brains process emotions, changes in the serotonin system are likely to be important in the development and/ or treatment of depression.

The findings from this latest review are not surprising. Depression has numerous symptom patterns, such that two people with depression can have seemingly opposite types of symptoms. For example, some sleep more when they are depressed while others suffer from insomnia.

As such, having met scientists and psychiatrists from all over the world, I have yet to meet a colleague who thinks that all cases of depression are caused by a simple “chemical imbalance” in serotonin. Indeed, the serotonin system is complex.

What remains likely is that changes in the serotonin system are contributing to certain symptoms in certain people. The challenge with this review is that it isn’t able to address this point because it has grouped together depression as if it is a single disorder, which from a biological perspective does not make sense.

There is consistent evidence that antidepressant medicines can be helpful in the treatment of depression and even life-saving. This latest paper does not change this. Patients must have access to treatments for depression.

Many of us know that taking paracetamol can be helpful for headaches and no one believes that headaches are caused by not enough paracetamol in the brain. The same logic applies to depression and medicines used in its treatment. All medicines can have side-effects and suddenly stopping any treatment can be potentially harmful.

Anyone taking a medicine for depression who is thinking of stopping treatment should discuss this with their doctor first.