Chemical imbalance theory debunked, but antidepressants still work

The chemical imbalance theory of depression has been debunked. However, it doesn't mean antidepressants don't work. In fact, they very much do.

Some scientists have always been skeptical about the effectiveness of antidepressants. But it's not surprising why they are. Their doubt is all down to the chemical imbalance theory: that depression is caused by low serotonin levels in the brain. We now know that's not the case.

Antidepressants are believed to work by increasing serotonin levels in the brain. So if low serotonin levels aren't the cause of depression, how can antidepressants be effective for depression?

It's all down to the origin of the chemical imbalance theory.

How did the chemical imbalance theory originate?

The first antidepressant medications were discovered by mistake in the 1950s. That is, they were meant for other functions, but one of the side effects was improved mood due to increased serotonin levels.

Iproniad was developed to treat tuberculosis, while imipramine was an antihistamine.

Interestingly, iproniad stops the enzyme that breaks down serotonin, while imipramine prevents the reuptake of serotonin after it has been secreted. In essence, both antidepressants increased the brain's serotonin levels.

But experts didn't know how those medications worked at the time their antidepressant effects were first observed in the 1950s. It's like treating someone for tuberculosis, only to find that their depression also improved. So those experts guessed (hypothesized) that the cause of depression must be chemical imbalance -- low serotonin in the brain. Hence, the birth of the chemical imbalance theory of depression.

The link between the chemical imbalance theory and antidepressants

So this is it. The death of the chemical imbalance theory doesn't amount to the death of antidepressants because antidepressants weren't developed out of the theory. On the contrary, the theory was born out of how antidepressants worked.

And the flaw in the researchers' conclusion back then in the 1950s was that research work wasn't as sophisticated as now.

When experts realized those drugs had antidepressant effects, they tested the patients' blood samples. The results showed that they had low serotonin levels in the blood and cerebrospinal fluid. Although they couldn't check the brain, the findings fit their hypothesis, and they quickly concluded that low brain serotonin levels caused depression. But the sample size was small, so the result was unreliable.

Since then, more extensive research has been carried out to debunk the chemical imbalance theory.

So, are antidepressants effective?

Pharmaceutical companies quickly picked up on the surmise of how increasing serotonin levels can improve depression symptoms. And they went on to manufacture antidepressants. So one would naturally think that the death of chemical imbalance theory would lead to doubt over the effectiveness of antidepressants.

The drugs are still used today and are as effective as ever, although names have changed. So should something effective be stopped because a theory linked to it has been debunked? Absolutely not.

You see, centuries ago and even till today, medicines were used for curing illnesses even long before their working principles were understood. That's how medical science is; it is pragmatic rather than theoretical.

The new research paper by Joanna Moncrieff and colleagues that finally debunked the chemical imbalance theory was birthed out of a mission to discredit the effectiveness of antidepressants. The researchers are critics of antidepressants because they don't believe in the chemical imbalance theory.

But their conclusion can be seen as this: those researchers in the 1950s that coined the chemical imbalance theory made a mistake. Antidepressants work, but they just didn't understand precisely how they worked. And till now, we still don't fully understand it either.

So should you use antidepressants?

Whether to use antidepressants is a matter of opinion and circumstances. Like many other treatments, it doesn't work very effectively for everyone. However, antidepressants are more effective for depression than placebo treatments.

And if you're battling depression, using antidepressants can be helpful, whether or not we understand how it works. It's like anesthesia. We don't fully understand how anesthesia works, but few people would reject it when they're about to undergo a serious surgical procedure.

Author

Satu H. Woodland, PMHCNS-BC, APRN Satu Woodland is owner and clinician of Hope Mental Health, an integrative mental health practice located at Bown Crossing in Boise, Idaho. She sees children, adolescents, and adults.  Ms. Woodland with her background in nursing, prefers a holistic and integrative approach to mental health care that addresses the mind and body together. While Ms. Woodland provides medication management services in all her patients, she believes in long-lasting solutions that include a number of psychotherapies, namely cognitive behavioral therapy, exposure and response prevention therapy, attention to lifestyle, evidenced based alternative psychiatric care and spirituality. If you’d like to gain control over your mental health issues, call Hope Mental Health at 208-918-0958, or use the online scheduling tool to set up an initial consultation.