Cognition & Reality

Sunday, 25 July 2010

Chemical Imbalances & Mental Imbalances

Filed under: Chemical Imbalance,Diagnosis — drtone @ 8:10 am

The widely believed and widely promoted claim that  emotional and mental disorders result from chemical imbalances in the nervous system could hardly be more defective. From a logical perspective, the proposition that mental disorders reflect neurochemical disorders confuses correlation and causation. From an empirical perspective, it confuses causes and cures. On the basis of this unwarranted assumption, doctors write millions of prescriptions every year for  medications that affect the levels of certain chemicals in the nervous system.

If antidepressants address an imbalance involving one or more neurotransmitters, it would make sense to assay the levels of those chemicals in an individual patient’s nervous system before prescribing a medication supposedly affecting those levels. That is never done in the millions of cases for which serotonin re-uptake inhibitors (SSRIs) are prescribed. Medicine has established neither the normal levels of such neurotransmitters as dopamine, serotonin and norepinephrine, nor a way of establishing the presence of either a deficiency or an excess of these chemicals in an individual. Therefore, the claim that chemical imbalances cause certain symptoms is without any empirical basis.

Although their efficacy is a matter of controversy, let us suppose, for the moment, that drugs such as Prozac and Zoloft do alleviate depression. Let us suppose, as well, that there is a reliable relationship between the neurochemical changes they produce and a reduction in psychiatric symptoms in those that ingest them. There would still be no reason to believe that the changes these drugs produce demonstrate a relationship between neurochemical imbalances and the mental imbalances they purportedly treat. If  aspirin cures my headache, does that mean the headache was caused by a “chemical imbalance” addressed by acetylsalicylic acid?

Let us further suppose that a reliable relationship has been established between a certain neurochemical deficiency and a psychiatric disorder, such as depression. There would still be no basis for inferring that the deficiency causes the depression, because the depression could cause the deficiency. Although every schoolchild knows that “correlation is not causation,” and although no one has demonstrated a reliable relationship between the two, the idea that abnormally high or low levels of serum serotonin “cause” depression, as promoted by psychiatrists and pharmaceutical companies, has captured the public imagination.

Thus, the supposed connection of “chemical imbalances” with mental and emotional disorders is a misconception promoted by psychiatrists and pharmaceutical companies that advances their own interests at the expense of the public interest. In another post, I will discuss the clinical implications of the massive propaganda campaign that has promoted this error in thinking.



  1. This is good clear thinking about something that most people who prescribe Prosac are not interested in investigating. They could, but they don’t want to. Throwing drugs at problems is inefficient at the very least and detrimental and dangerous on the other end of that equasion.

    Comment by annie wallack — Wednesday, 4 August 2010 @ 5:48 pm | Reply

  2. […] Filed under: Uncategorized — drtone @ 10:07 am As I have already indicated here and here, I view with great skepticism the proposition that our behavioral dispositions, let alone our […]

    Pingback by “Innateness”: Burden Of Proof « Cognition & Reality — Thursday, 26 August 2010 @ 10:07 am | Reply

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