Why Mental Illness Isn't Exactly a Brain Disorder

It’s a common thing nowadays to hear mental illnesses referred to as “brain diseases” or “brain disorders”. The National Alliance on Mental Illness (NAMI) has made a particular point of this.

In a policy statement in 2014 (www.nami.org/TextTemplate.cfm?Section=NAMI_Policy_Platform&Template=/ContentManagement/ContentDisplay.cfm&ContentID=124562 ), NAMI made the following statements:

 “NAMI advocates for research and services in response to major illnesses that affect the brain, including schizophrenia, schizoaffective disorder, bipolar disorder, major depressive disorder, obsessive-compulsive disorder, panic and other severe anxiety disorders, borderline personality disorder, post traumatic stress disorder (PTSD), autism and pervasive developmental disorders, and attention deficit/hyperactivity disorder.”

“NAMI … believes that mental illness is essentially biological in nature. Mental illness affects behavior and behavior can affect mental illness—but mental illnesses are not behavioral.  The term ‘behavioral health’ obscures and hinders effective treatment of co-occurring disorders. Also, because behavior is perceived as a matter of choice (‘good’ or ‘bad’ behavior), the very term ‘behavioral health’ can add to the stigma and discrimination endured by people living with a mental illness.”

“Therefore, throughout this document, we are discussing the term ‘brain disorder(s)’ interchangeably with mental illness and serious mental illness.”

The NAMI statement is not easy to unpack, but its goal is clearly to emphasize a medical-biological view of all mental illnesses whether they have strong genetic components (autism, for example) or derive from factors in the environment (PTSD). It is true that the term “behavioral health” is confusing, because surely a behavior cannot be healthy or unhealthy independent of some other aspect of the individual, but this does not seem to be the reason for NAMI’s rejection; instead, there is an assumption that behavior is generally seen as voluntary, and that calling it “good” or “bad” indicates this and leads to stigmatization of mentally ill persons. These various choices of terminology are confusing, as they conflate mental illness both with sin and with problems like seizure disorders, Parkinsonism, and dementia, which are clearly brain disorders but have little in common with the mental illnesses listed earlier.

Is mental illness properly seen as a type of brain disorder, or has this view been determined by public relations concerns like those of NAMI and by a history dating back 30 years or more? Before discussing possible answers to this question, let me point out that whether or not moods and behavior that distress mentally ill persons and others are brain disorders, it is probably not appropriate to think of them as intentional, or to blame adult patients or the parents of mentally ill children for disturbing characteristics. Considering non-brain factors as contributing causes of mental illness does not condemn us to hating the mentally ill, or using confinement, starvation, and cold as “treatments” for their challenges.

Gregory Fritz, writing his editorial column in the Brown University Child and Adolescent Behavior Letter, recently addressed some of these issues with respect to brain disorders as a cause of depression (“The chemical imbalance explanations for depression: Setting the record straight”, CABL, 30(9), 8). Fritz noted that he still hears “the idea of a chemical imbalance discussed in relation to depression, though fortunately not among psychiatrists. Given that there is no empirical evidence for this explanation of the cause or treatment of depression [my italics—JM], why is it so tenaciously a part of the lay understanding of the disorder?” (as indeed brain disorders are a part of popular assumptions about all mental illnesses).

Fritz went on to say that the chemical imbalance theory of depression was not invented by the public, but “was presented to them by psychiatrists, the popular press, and pharmaceutical advertisements starting with vigor in the 1980s… The hypothesis was that altered levels of neurotransmitters lead to disturbances of mood. It was an attractive hypothesis, one that was behind the development of the SSRI family of antidepressants—for which there is solid evidence of benefit in treating depression.” But, Fritz commented, “There were two major problems with the popularization of the chemical imbalance idea: (1) an appealing hypothesis was treated as fact [my ital—JM], and (2) evidence that SSRIs had a significant clinical impact… was treated as proof of the mechanism of depression.”

Why have ideas about brain problems as causes of mental illness become so entrenched? The NAMI material suggests that one real reason is the belief that blame and stigmatization are diminished when brain disorders are pointed to as the basis of mental problems. Fritz’s editorial also emphasized the human “distaste for ambiguity” as responsible for the assumption that depression is caused by chemical imbalances in the brain. He pointed out the difficulties we have with dealing with the “complex truth about depression—that many genetic, environmental, biological, social, physiological, and psychological factors interact with development and other, still unknown factors in complicated ways to produce depression, and that we’re still not sure how antidepressants work”; this statement could be applied equally to other forms of mental illness.  

Evidence about differential effects of early maltreatment on different parts of the brain suggests that attributing mental illness to “brain disorder” in general is painting with too broad a brush. Simultaneously, though, the concept appears to be too narrow when we consider the list of known and unknown factors that appear to help determine mental illness. In either case, overemphasizing the role of brain structures and functions as causes of mental illness is treating a hypothesis as a fact, which is not likely to lead us to any real understanding.  We can surely treat mentally ill children and adults benevolently without oversimplifying the causes of their problems.