Antidepressants and the Serotonin Delusion: a Big Pharma Marketing Ploy

How a humble neurotransmitter became the poster child for depression and fueled a billion-dollar industry.

Imagine, if you will, a world in which the complexity of human emotion and behavior could be reduced to a single molecule sloshing around in our brains. Sounds absurdly reductionist, doesn't it? Well, welcome to the wild ride that is the serotonin hypothesis of depression, the saga of a health scandal.

For decades, the public has been told that depression is caused by a chemical imbalance and that antidepressants work by targeting this mechanism. Millions of people have decided to take antidepressants based on this information.

As the prominent British psychiatrist Dr. Joanna Moncrieff details in her book “Chemically Imbalanced: The Making and Unmaking of the Serotonin Myth”, although the serotonin theory of depression was never actually proven, that didn’t stop it from becoming the foundation of modern psychiatric treatment—and a goldmine for the pharmaceutical industry. Chemically Imbalanced tells the story of a scientific myth and its consequences. It takes us on a journey through the twisted corridors of psychiatric history, Big Pharma marketing, and scientific hubris.

The birth of a convenient myth

Picture this: It's the late 1950s. Psychiatry is desperate for legitimacy in the face of psychoanalytic dominance. The idea that mental illness could be reduced to brain chemistry began to gain traction when researchers hypothesized that neurotransmitter imbalances might underlie psychiatric disorders. It was an intriguing idea, but the evidence was weak. Instead of rigorous proof, what followed was a perfect storm of scientific speculation, media oversimplification, pharmaceutical greed, and opportunism.

Now, if you're a pharmaceutical company, the serotonin hypothesis is better than striking oil in your backyard. You've got a simple problem (not enough serotonin) and a simple solution (drugs that boost serotonin). By the 1990s, the “chemical imbalance” theory had become gospel, with doctors and patients alike believing that depression was simply a neurochemical problem waiting to be fixed.

This narrative wasn’t just a matter of scientific inquiry—it was genius marketing. SSRIs (Selective Serotonin Reuptake Inhibitors) like Prozac and Zoloft burst onto the scene with the promise of correcting this supposed imbalance. The message was seductive: depression wasn’t your fault; it was a biological glitch, easily treatable with a pill. No need for expensive therapy, or messy discussions about trauma, meaning, or existential dread—just tweak your brain chemistry, and you’re good to go. Cue the pastel-colored commercials featuring sad people walking on beaches, transformed by the magic of SSRIs.

Fast forward a few decades, and this tentative hypothesis has morphed into an unshakeable dogma, fueling an industry worth USD 13.5 billion in 2020. Serotonin, that lucky little neurotransmitter, gets cast as the star of this neurochemical drama. Nothing could stop the serotonin train from chugging along at full steam. Unfortunately, this hypothesis, while convenient and highly profitable, turned out to be more fiction than fact.

The cracks in the story

The problem? No one ever found clear evidence that depressed individuals have lower serotonin levels than those without depression. Multiple studies, including large meta-analyses, have failed to establish a consistent correlation link between serotonin levels and depression. Some people with depression have normal or even elevated serotonin, while others who lack symptoms have low levels. In fact, in 2022, Dr. Moncrieff and colleagues¹ published a review concluding that there is no compelling evidence that serotonin deficiency causes depression at all.

While SSRIs are helpful for some people, their success in mild to moderate cases is often comparable to placebo. They were far from the miracle drugs they were touted to be. And pesky scientists kept pointing out inconvenient facts, like that SSRIs often take weeks to work, even though they boost serotonin levels almost immediately. They don't "correct" an imbalance, because there is no known baseline of "correct" serotonin levels to begin with. Instead, they alter brain function in complex, poorly understood ways, sometimes beneficially, and sometimes not.

The perfect storm

So how did we end up here? Dr. Moncrieff argues that it's a perfect storm of four colliding factors:

1. Psychiatry's desperate need for a biological basis for mental illness.

2. The profit motive of pharmaceutical companies.

3. The media's love of simple explanations for complex phenomena.

4. And, perhaps most importantly, everyone’s deep-seated desire to believe that psychological suffering can be explained by something as straightforward as a chemical imbalance.

But here's the kicker: even as the scientific community began to back away from the serotonin hypothesis, the idea remained firmly entrenched in the public consciousness, fueling a trend of overprescription and overconsumption.

The consequences in numbers

• In Europe, between 2000 and 2020, the average antidepressant consumption across 18 European countries rose from 30.5 to 75.3 defined daily doses (DDD) per 1,000 people per day, marking a 147% increase. ²

• In France: the Agence française de sécurité sanitaire des produits de santé (AFSSAPS) indicates a 58% increase in the number of antidepressant units sold to pharmacies between 1994 and 2004.³

• Worldwide, as of 2017, antidepressant use has increased by 40%.

• In the United States, according to the National Center for Health Statistics, between 2015 and 2018, 13.2% of adults aged 18 and over reported using antidepressants in the past 30 days.

• In the UK, 70.9 million antidepressants were prescribed in 2018, nearly double the amount prescribed a decade earlier.

• European Union: A 2018 OECD report showed that antidepressant consumption doubled in EU countries between 2000 and 2015.

• Duration of Use: Long-term use of antidepressants is common. In the US, 68% of people aged 65 and over who take antidepressants have been doing so for 5 years or more.

The real cost of the chemical imbalance myth

The persistence of this narrative isn't just an academic issue; it has real human consequences. By reducing depression to a biochemical problem, we risk ignoring the psychological, social, and environmental factors that contribute to mental suffering. A person trapped in a soul-crushing job, stuck in an abusive relationship, or struggling with unresolved grief doesn't necessarily need a serotonin boost, they need meaningful change.

Framing depression as a simple chemical deficiency has led to overmedication. Millions of people are prescribed SSRIs with the expectation that these drugs will correct a biological flaw, often without being offered alternative treatments such as therapy, social support, or lifestyle interventions. Worse, many patients who try to stop taking SSRIs experience severe withdrawal symptoms, reinforcing the belief that they are biologically dependent on these drugs.

One of the most significant consequences of the over-reliance on SSRIs has been the decline in the prescription of psychotherapy for depression. As antidepressants became the go-to solution, therapy—once considered a cornerstone of mental health treatment—was increasingly sidelined. Insurance companies and health care systems that prioritize cost-effectiveness often favor medications over therapy because of their lower short-term costs, despite evidence that psychotherapy can provide more durable, long-term benefits.

Studies suggest that a combination of therapy and medication is often the most effective approach to treating depression. However, because SSRIs are so readily prescribed, many patients never even receive a referral for therapy. This over-medicalization of depression ignores the deeply personal and situational nature of mental distress and reduces treatment to a pharmacological fix rather than a holistic process of healing and growth.

So, what now?

So where does this leave us? In a bit of a mess, to be honest. We've spent decades and billions of dollars chasing a theory that, while not entirely wrong, is about as nuanced as explaining World War II by saying "some people got angry."

Dismantling the serotonin myth doesn’t mean throwing medication out the window. For some, antidepressants do provide relief, especially in cases of exogenous depression and there’s no shame in using them. But we need to be honest about what they do—and what they don’t do. Rather than pushing a one-size-fits-all biochemical model, we should embrace a broader, more nuanced view of mental health—one that accounts for the full complexity of human experience.

The reality is that depression is a complex interplay of genetic, environmental, psychological, and yes, neurochemical factors. Serotonin plays a role, sure, but so do a host of other neurotransmitters, hormones, and neural circuits.

A bit of critical thinking

What can we learn from this serotonin saga?

1. Be wary of simple explanations for complex phenomena. The brain is not a bowl of chemical soup; it's more like a quantum computer.

2. Science is a process, not a set of facts. Today's gospel truth might be tomorrow's quaint historical footnote.

3. Follow the money. When billions of dollars are at stake, scientific objectivity can suddenly develop a mysterious case of myopia.

4. Our desire for simple explanations can sometimes override our critical thinking. We're all susceptible to a good story, especially when it promises to explain our suffering.

A new dawn in depression research?

As we move beyond the serotonin myth, new avenues of research are opening up. From the role of inflammation in depression to the potential of psychedelics, we're beginning to appreciate the true complexity of mood disorders.

But perhaps the most important lesson from Dr. Moncrieff’s book is this: we need to be humble in the face of the brain's complexity. In the end, the story of the serotonin hypothesis is a tale of hope, hubris, and the never-ending quest to understand ourselves. Depression is not just a glitch in brain chemistry. It’s a deeply human condition, shaped by biology, yes, but also by relationships, history, environment, and meaning. This understanding might not fit neatly into a marketing campaign, but it’s a truth worth aiming for.

1. https://joannamoncrieff.com/papers/

2. https://www.euronews.com/health/2023/09/09/europes-mental-health-crisis-in-data-which-country-uses-the-most-antidepressants?utm_source=chatgpt.com

3. https://www.irdes.fr/EspaceAnglais/Publications/WorkingPapers/DT21EvoluAntidepressantConsumFranceGermanyUk.pdf?utm_source=chatgpt.com