Is depression really due to a chemical imbalance in the brain?

Depression and the Chemical Imbalance Theory

In my last post around this topic, I discussed how anti-depressants have been shown to be no more effective than placebo in treating depression and why a lot of the time, they are not an effective treatment for depression.

Anti-depressants increase availability of certain neurotransmitters (e.g. seretonin) in the brain, as it was once thought that depression resulted from a “chemical imbalance” of these neurotransmitters. However,  the “chemical imbalance” theory of depression is not grounded in much evidence, which is probably why anti-depressants have been shown to be no more effective than placebo in treating depression.

This post will challenge the “chemical imbalance” theory of depression, which will help you understand the reasons as to why anti-depressants lack efficacy in treating all cases of depression.

Depression is unlikely to be caused by a chemical imbalance in the brain

It is so ingrained into our psyche (which is probably due to the media and the over prescription of anti-depressants) that depression results from a “chemical imbalance” in our brain and anti-depressants aim to correct this imbalance. The simplicity of the chemical imbalance theory may be a convenient way to prescribe medications, however the similarity of anti-depressants to placebo, certainly casts doubt on this theory.

This is because we have taken a multi faceted disease, which involves a complex interaction between genetic, diet, lifestyle, environmental and social factors and narrowed it down to the imbalance of a couple of neurotransmitters in the brain and developed drugs to increase these neurotransmitters.

There are certain things that we know about neurotransmitters and how they function, which has further cast a doubt on the chemical imbalance theory.

For example, we know that 100 or more neurotransmitters have been identified in the pathology of depression and some patients may have low seretonin but others don’t. Some have increased amounts.

Cocaine and meth both increase serotonin and norepinephrine but don’t decrease depression. Also, some drugs don’t affect serotonin and norepinephrine, however they help with depression. And lastly, anti-depressants take a few weeks to effect your mood however changes in neurotransmitter balance are seen very soon after drug administration.

Obviously these factors cast doubt on the chemical imbalance theory of depression, however at the end of the day it is far easier and cheaper for a health care system to characterise depression as a physical disease due to a simple chemical imbalance, prescribe a drug and send someone on their way. Meanwhile, it is a lot harder and costly to address the social and environmental aspects that contribute to the disease. We fail to remember that our emotions effect our physiology and our physiology effects our emotions.

So if a chemical imbalance does not cause depression, then what does?

Well, there is no one single cause of depression. As I mentioned in the last newsletter, it is a multi-faceted disease that has many different causes and effects people in very different ways.

New evidence is emerging that depression, on a physiological basis, is an inflammatory disease and there is a lot of evidence to support this. For example:

  1. When healthy patients are injected with LPS (an inflammatory molecule produced from bacteria) they display depressive symptoms.
  2. An anti-viral drug used to treat hepatitis called interferon causes significant inflammation in the body and one of its potential adverse reactions is depression.
  3. People with depression usually have heightened inflammatory markers such as CRP and IL-

    Inflammation in the body seems to disrupt various brain functions that regulate mood. 

So where does the inflammation come from? Well, the current theory is that this inflammation originates in our gut, which is caused by a dysfunction of the gut-brain axis.

Our gut is filled with millions of bacterial species and research is starting to reveal how crucial these gut bacteria are to our overall health. An imbalance of good and bad bacteria in our gut is starting to be implicated as a driving factor behind many chronic diseases, including depression.

In depression, it is thought that an overgrowth of “bad” bacteria in the gut causes a condition called small intestinal bacterial overgrowth (SIBO). SIBO increases the production of inflammatory molecules in the gut, which enter the blood stream, travel to the brain and then activate inflammatory pathways in the brain. Inflammation in the brain can potentially cause depression in those who are predisposed.

It is well established in the scientific literature that there is a strong link between the microbes in our gut and signalling in our brain. This connection is called the gut-brain axis link. The gut-brain axis explains the correlation between IBS (irritable bowel syndrome) and depression. Especially because IBS is closely associated with SIBO and SIBO is associated with depression.

This gut-brain link also provides an explanation as to why probiotic and prebiotic supplementation has been shown to help with depressive symptoms. It also explains why some people can get depression without any significant life circumstances (e.g. poverty, unemployment, negative life situations, life altering events) that would warrant a person to get depressed.

This is because we know that poor diet and lifestyle factors such as a diet high in processed food, excess alcohol consumption, smoking, long term psychological stress, chronic lack of good quality sleep and a lack of exercise, all contribute to bacterial overgrowth through various mechanisms. 

They also make a person feel and look unhealthy, which therefore further contributes to depression. When people don’t look their best or feel unhealthy, they are less likely to look after their health, leading to a viscous cycle. 

Our diet and lifestyle choices effect our physiology and then our physiology effects our emotions, mood, cognition and behaviour. 

Independent of the gut-brain axis link, depression can certainly be a result of stressful life circumstances as we know stress can have inflammatory and disrupting effects on the brain. This can cause depression in the predisposed. It must also be noted that stress is not only psychological. Poor diet and lifestyle habits are also a form of physical stress and this causes inflammation in the body.

In today’s modern world we are more stressed than ever, which is probably a huge contributing factor to the rise in depression.

We live high stress, fast paced lifestyles, where we are working more than ever and having less fun and less social connection.

There are also many aspects of our modern culture that create an environment conducive to stress, unhappiness, social isolation and therefore depression.

For example, our modern environments increase the risk of low self esteem and a lack of self worth, social connection, fun and life purpose. These can all contribute to depression. 

I think if we recognise that depression goes far deeper than a few neurotransmitters in the brain, then we can address the underlying causes of this disease and put preventative measures in place, leading to better and more long term therapeutic outcomes.

We need to start looking at all the complex and multifaceted aspects in our lives that disrupt our gut microbes and drive inflammation in our bodies/brains. 

Treating the drivers of inflammation should replace anti-depressants 

Using drugs that are no more effective than placebo, with harmful side effects may create dependency and numb our senses. Therefore preventing growth and self-change in order to get out of a lifestyle cycle that is causing/contributing to depression.

As mentioned in last months newsletter, because anti-depressants have been shown to be no more effective than placebo, this means that whether a person takes a anti-depressant or placebo, studies show that both have the same efficacy in treating depression, which is pretty low.

This means 2 things:

1. If a placebo can help depressive symptoms similar to an anti-depressant, it is unlikely chemical imbalances in the brain drive depression.

2. We know depression is exacerbated and driven by a lack of hope, therefore taking a pill and being told it will help a person’s depression, gives hope to some people. This can cause a chemical cascade of things to help people feel better. This means if a person has negative connotations to anti-depressants or even feel neutrally about them, these drugs will be unlikely to help, if at all, due to their actual lack of therapeutic benefit. Anti-depressants may work in people who believe they will work, which is what makes placebo drugs just as effective. 

Based on this, I believe that instead of giving drugs that have side effects and the same results could be achieved with a placebo drug. Treating depression should take a holistic approach by addressing the underlying inflammatory causes of the depression.

If health practitioners can build good therapeutic relationships, provide holistic care and establish hope in their patients with treatments other than anti-depressants, we may see better outcomes for treating depression. 

Wrap up

I want to make it clear that this article was not written to criticise doctors.

We cannot be angry at our health practitioners for prescribing anti-depressants as they are going by what they have been taught. There is no doubt that many doctors refer their patients to psychologists and may even recommend lifestyle changes to patients. However, patients are still usually put on anti-depressants, which I believe should be re-thought due to the existing evidence on these drugs. 

I am merely advocating for a paradigm shift as depression is reaching epidemic levels and I feel like our current treatment of it is proving ineffectual.

If you suffer from depression or know someone who does, the first step would be to find a good health care practitioner that is aware of the current research and is willing to work with you to change various environmental, cognitive and lifestyle habits that may be the underlying causes to your depression (i.e. Oak Health).

Also, they may be able to help introduce certain drug free treatments that have been shown to be helpful in treating depression such as:

  • Psychotherapy
  • Cognitive based therapy
  • Meditation and yoga
  • Animal therapy
  • Nature therapy
  • Exercise 
  • Improving sleeping quality and quantity
  • Light therapy
  • Healthy diet changes
  • Supplementation with herbs and nutrients.

Due to the lack of strong evidence for anti-depressants and the side effects, I believe these options should be explored first in depression treatment. Anti-depressants should be seen as a last resort, while trying to integrate the above treatments in a gradual, habit based manner that doesn’t overwhelm people. Furthermore, even if someone is on anti-depressants, these treatments should still be addressed.

If you suffer from depression, call Oak Health today or book an appointment online to find out how practical and evidence based diet and lifestyle changes, as well as herbal and nutritional supplementation can be used to address the underlying causes of your mental health issues. 

You may also want to enquire about the 6 week mental health treatment program.

Note: If you are currently taking anti-depressants, DO NOT stop taking them as a result of reading this article. Please consult your doctor first.