Alankrita Singh (28), writer, Kolkata, was diagnosed with depression a few months back. Her symptoms included a constant state of low mood and loss of interest in activities. “I didn’t feel like getting out of my bed and would go days without taking a shower because of this constant state of sadness and lethargy.” She adds,” Over time, I lost interest in photography and even watching sunsets – two things I loved the most.”
Many people relate to her story, and efforts have been made to develop theories that can shed light on the underlying causes of the symptoms of depression. One of the most prevalent theories in this area has been the serotonin theory of depression.
The serotonin theory of depression
According to the serotonin theory of depression, chemical imbalances in the brain, particularly involving serotonin, are responsible for the symptoms of depression. This theory was initially put forth in the 1960s by Coppen, who, in his article, ‘The Biochemistry of affective disorders’, stated that biochemical changes played a significant role in the development of mood disorders like depression.
One of the major reasons for the consistent interest in the link between serotonin and depression is the fact that selective serotonin reuptake inhibitors (SSRIs) that increase the serotonin levels in the brain, are proven to be effective antidepressants for some individuals.
However, a 2022 review paper published in Molecular Psychiatry has contradicted the fundamental findings of the serotonin theory of depression.
A systematic review study by Dr Moncrieff
Dr Joanna Moncrieff, professor, consultant psychiatrist, and the lead researcher of the study titled, ‘The serotonin theory of depression: a systematic umbrella review of the evidence’ told Happiest Health that there had been a unanimous understanding among many mental health professionals that serotonin might not be a factor at play when it comes to depression. “It was almost like a rumour with nothing to substantiate it,” she says. She explains that this study was necessary because we needed evidence that can either support or contradict this widespread belief.
Therefore, with a group of other researchers, she collected and evaluated evidence on the link between depression and lowered serotonin concentration. They did a systematic review of studies that have already been done.
The study found that there is neither substantial evidence suggesting that depression is caused by lowered serotonin activity, nor a link between the two.
Dr. Moncrieff suggests that the study’s implications provide people diagnosed with depression with more control over their treatment options. This is because the study found no scientific evidence supporting the idea that depression is a brain disease. Therefore, individuals with depression can make an informed choice about their treatment.
Is depression caused by a chemical imbalance?
Depression is a mix of different symptoms. Attributing its cause to a deficiency in a single neurotransmitter might reduce a complex condition to a simpler narrative from a bio-medical perspective. It is usually understood to be a heterogeneous condition with multiple underlying causes.
Dr Moncrieff adds that social issues like housing problems, finances, and drug and alcohol dependency among others have a huge role to play when it comes to understanding the causes of depression. She mentions that many studies have conclusively shown that prolonged exposure to stress and adverse experiences may lead to depression more than genes.
Many such factors surfaced when Singh underwent therapy for depression. “Years of body shaming, living a restricted life, growing up with an insecure attachment style, and being diagnosed with diabetes at 20 seemed to have contributed to my depression,” she says. “Growing up with a lack of confidence, self-worth, and self-belief made it worse,” she adds.
Rethinking mental health conditions
It is time that we rethink mental health conditions like depression from a more critical lens to understand the factors causing it. It is important to keep different environmental factors in mind. There is no blanket treatment that suits all. However, a broad framework of the same can help identify the factors that might have led to the development of the condition. Moreover, practising research-backed coping techniques and therapy models can help improve the condition. This may include any kind of physical movement, exercise, and cognitive behavioural therapy among others.