I think that's important that we need to flip this round, and actually it's a really good thing for people to know that if they're depressed, we don't have evidence that that's originating in their brain, there's anything wrong with their brain.

You know, I also think that's empowering because it tells people, and it may be difficult at first to get your head around this, but it does also tell people, well, you know, your brain's working normally.

So you can probably get yourself out of this, it may not be easy, maybe a lot of hard work, but you know, there's no biological reason why you can't.

Well, that's the voice of Professor Joanna Moncryff, a psychiatrist and academic who's working to debunk the chemical imbalance theory of depression.

This is the Lizard Wellbeing Show, the podcast helping us all have a better second half. I'm Lizard, and I'm on a real mission to find ways for all of us to thrive in later life by investing in our health and our wellbeing today.

And as you well know, if you're a regular listener, a big part of this mission is about pushing the boundaries of science, questioning accepted wisdom, questioning, examining, probing, and this is precisely what Joanna has been doing.

Well, working out of University College London, her research consists of analysis of all aspects of psychiatric drug treatment, including subjective experiences, political aspects of drug treatments, and a critique of evidence for drug treatments.

Well, Joanna and her colleagues recently conducted a study, a review into selective serotonin reuptake inhibitors SSRIs, and they're one of the main medications prescribed to those with depression.

Now, it's generally believed that they work by increasing serotonin levels in the brain, thereby alleviating low mood, but Joanna's review of 50 years worth of studies concluded that there's, quote, no clear evidence that low serotonin causes depression in the first place.

Well, NHS prescribing figures tell us that more than 8 million people in England are on antidepressants, you may well be one of them.

Now, I don't feel that Joanna's paper undermines the efficacy of antidepressants. For those they have worked for, your subjective experience isn't being questioned, but it does go some way towards helping us understand how our brain chemicals do, or perhaps don't play a role in causing depression.

Now, I know that questioning such a deeply held accepted wisdom can feel uncomfortable to say the least, but science is really about continually learning and adapting to new knowledge.

So, let's all, me included, go into this chat with a curious and open mind.

Well, Joanna, a very warm welcome to the show, and I'm so looking forward to this conversation.

Sure, we start perhaps then with this study that you've conducted into the chemical imbalance theory of depression, then because this was a review of the metronalysis of previous evidence.

Is that about the shape of things? That's right, that's right. Yes, so this was a paper that we published last summer now, and it was what's called an umbrella review.

So, because there's such an enormous amount of research on serotonin and depression, what we did was we looked at all the reviews that have been done of existing research in the main areas of research so that we could get it all together and have an overview, and that's what no one has done really before.

And I wanted to do it because it's been rumored for a long time really that there wasn't any evidence to support the idea that depression is caused by a chemical imbalance in general and an imbalance of serotonin in particular for quite a few years now, but no one had really produced an overview of the scientific evidence in order to back up that claim.

So, that's why I wanted to do that. Yeah, I mean, absolutely fascinating. Before we dive right in, give us the top line then of what you believe about the chemical imbalance theory of depression and what you feel should be the dominant line of thought instead.

So, what we found in a nutshell is that there was no convincing evidence from any of the six main areas of research that we looked at that depression is associated even with serotonin let alone cause.

Oh my gosh, something proving that something is is is causal is you know is quite a difficult thing, but we didn't even find evidence that it is associated with depression and serotonin is there are other theories about other brain chemicals and depression, but serotonin is the most thoroughly researched.

And so, I think we can conclude from that that there really isn't good enough evidence to support the idea that depression consists of or is caused by a chemical imbalance and obviously that's really, you know, really important because people have been told for decades now that that is the case.

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