Over the last couple of days, a class of anti-depressant drugs, known as SSRIs, has been the subject of much discussion in the media.
But what are SSRIs? How do they work, and are they actually effective for treating depression?
What are SSRIs?
Selective Serotonin Reuptake Inhibitors are a class of drugs which are used to treat certain mental health conditions such as depression, PTSD, OCD and anxiety disorders.
SSRIs first came into general use as an anti-depression treatment in the 1980s and are now widely used, usually in combination with talking therapies such as Cognitive Behavioural Therapy.
How do SSRIs work?
SSRIs alter the way serotonin works in the brain. Serotonin is a neurotransmitter, that also acts like a hormone, and carries messages between the nerve cells in our brains and throughout our body’s nervous systems.
Normally once serotonin has carried these ‘messages’ between nerve cells, it is reabsorbed. This is known as ‘reuptake’, and it is this that SSRIs block from happening.
Because the SSTIs stop serotonin from reabsorbing, there is more serotonin available to pass even more messages around the brain and body. It is presumed that this is how SSRIs relieve depression, at least in part.
Why are people talking about SSRIs now?
SSRIs have been the subject of discussion recently in the media following the publication of a paper that has reviewed 17 studies about serotonin. The authors wanted to see if there was evidence that depression is associated with lowered serotonin concentrations. They couldn’t find any such evidence.
This paper has questioned the role that serotonin plays in depression and, by implication, the effectiveness of SSRIs in this condition – but it’s important to note that this was not the purpose of the paper.
To say that low serotonin levels are the cause of depression is far too simplistic. Whilst many experts agree that serotonin often plays a role in major depressive disorders, the causes of depression are far more complex and involve environmental factors, socio-economic influences, other physical and medical conditions and even our personal experiences such as violent events or childhood trauma.
Prof David Curtis, Honorary Professor, UCL Genetics Institute, said:
“This paper does not present any new findings but just reports results which have been published elsewhere, and it is certainly not news that depression is not caused by “low serotonin levels”. The notion of depression being due to a “chemical imbalance” is outmoded, and the Royal College of Psychiatrists wrote that this was an over-simplification in a position statement published in 2019. Nor is it the case that SSRI antidepressants increase serotonin levels. Their immediate action is to alter the balance between serotonin concentrations inside and outside neurons, but their antidepressant effect is likely due to more complex changes in neuronal functioning, which occur later as a consequence of this. It is very clear that people suffering from depressive illness do have some abnormality of brain function, even if we do not yet know what this is, and that antidepressants are effective treatments for severe depression, whereas interventions such as exercise and mindfulness are not. It is important that people with severe depression are not discouraged from receiving appropriate treatments, which can make a huge difference to them and those around them.”
So, are SSRIs effective?
As with all treatments for physical and mental health conditions, the answer is: it depends.
For some people, SSRIs are highly effective. For others, they seem to make little or no difference.
In many cases, SSRIs can help to improve symptoms, but only when used in conjunction with other forms of treatment such as Cognitive Behavioural Therapy.
More research is needed to better understand why SSRIs work for some people and not others.
Dr Michael Bloomfield, Consultant Psychiatrist and UKRI Principal Clinical Research Fellow, Translational Psychiatry Research Group Head, UCL, said:
“Many of us know that taking paracetamol can be helpful for headaches, and I don’t think anyone believes that headaches are caused by not enough paracetamol in the brain. The same logic applies to depression and medicines used to treat depression. There is consistent evidence that antidepressant medicines can be helpful in the treatment of depression and can be life-saving. Antidepressant medicines are one type of treatment alongside other types of treatment like psychotherapy (talking therapy). Patients must have access to evidence-based treatments for depression, and anyone taking any treatment for depression who is contemplating stopping treatment should discuss this with their doctor first.”
Should I stop taking my anti-depressants?
It is very important that if you have been prescribed anti-depressants by your doctor, you do not suddenly stop taking them. Doing so can cause symptoms such as dizziness, nausea, mood swings, brain fog and even, in some cases, suicidal thoughts.
Instead, you should talk to your doctor about your treatment options and follow their recommendations.
For more information, there are some useful resources here:
SSRIs – information from the NHS
Stopping anti-depressants – advice from the Royal College of physicians