125)In his book, Valenstein clearly and systematically dismantles the chemical imbalance theory: Another problem is that it is not now possible to measure serotonin and norepinephrine in the brains of patients.
Estimates of brain neurotransmitters can only be inferred by measuring the biogenic amine breakdown products (metabolites) in the urine and cerebrospinal fluid.
It’s going to take a while to explain the history of this theory, why it is flawed, and how continues to persist in light of the complete lack of evidence to support it. The first antidepressant, iproniazid, was discovered by accident in 1952 after it was observed that some tubercular patients became euphoric when treated with this drug.
I will try to be as concise as possible, but there’s a lot of material to cover and a lot of propaganda I need to disabuse you of. A bacteriologist named Albert Zeller found that iproniazid was effective in inhibiting the enzyme monoamine oxydase.
The ineffectiveness of antidepressant drugs when compared to placebo cast even more doubt on the “chemical imbalance” theory.
(See my recent articles Placebos as effective as antidepressants and A closer look at the evidence for more on this.)Folks, at this point you might want to grab a cup of tea.
Since reserpine lowered levels of serotonin, norepinephrine and dopamine, and caused the effects observed in animals, it was concluded that depression was a result of low levels of biogenic amines. However, it was later found that reserpine only rarely produces a true clinical depression.
For example, Pfizer’s television advertisement for Zoloft states that “depression is a serious medical condition that may be due to a chemical imbalance”, and that “Zoloft works to correct this imbalance.”Other SSRI advertising campaigns make similar claims.
The Effexor website even has a slick video explaining that “research suggests an important link between depression and an imbalance in some of the brain’s chemical messengers.
The “chemical imbalance” theory is so well established that it is now part of the popular lexicon. It takes a complex and heterogeneous condition (depression) and boils it down to a simple imbalance of two to three neurotransmitters (out of more than 100 that have been identified), which, as it happens, can be “corrected” by long-term drug treatment.
This clear and easy-to-follow theory is the driving force behind the billion worth of antidepressant drugs sold each year.