Apr 26 2007
In my previous posts on this topic I have argued that mental illnesses are as real and scientific as any medical entities, they often have a biological basis in brain function and we now have the tools to see aspects of this dysfunction, there is no clean distinction between mental and other medical symptoms as even classical pathology can cause psychiatric symptoms, the clinical basis of their diagnosis is legitimate medicine, and objections to the very existence of mental illness are not valid. But even many who accept all this still may have a problem with the current practice of mental health, especially the tendency to overdiagnose and prescribe drugs to treat mental symptoms. Today I will address these concerns.
First it is important to recognize that these questions are distinct from the underlying question of whether or not mental illness diagnoses are legitimate and represent real biological entities. Dr. Baughman and other mental illness deniers often make, in my opinion, the argument from final consequences logical fallacy – the implementation of mental health is flawed, therefore the underlying theories must also be flawed.
Is ADHD Overdiagnosed?
As I discussed previously, the diagnosis of mental illness is comprised of a clinical assessment – having a sufficient number of signs and symptoms as determined by an experienced clinician, and also includes ruling out with diagnostic testing underlying medical problems that can secondarily cause the mental symptoms (for example a frontal lobe tumor causing psychosis or hyperthyroidism causing anxiety). The same is true of many disorders for which a clear pathophysiological cause is not known, or for which there is no reliable laboratory test.
As some have pointed out in the comments to my previous posts, clinical diagnoses are in general more difficult and less reliable than biological diagnoses – although this is not always the case. There is an exaggerated sense of value in biological tests, and even physicians may over rely on such tests. In fact, all tests (history, exam, blood testing, imaging, biopsy, etc.) have a sensitivity (calling a true positive positive) and specificity (calling a true negative negative). Clinical diagnostic criteria are no different. Some clinical diagnostic criteria can be more sensitive and specific than any biological test. You have to use evidence to make a case-by-case decision.
Mental illnesses do have a special problem in that human thought and behavior is particularly complex with multiple influences, not only from brain physiology and anatomy but from transient effects on the brain (like sleep deprivation), culture, family situation, personality, daily events and stressors. Also, one mental disorder may influence other mental processes and symptoms, and therefore there is often great overlap in symptoms. For example, a primary anxiety disorder may make a child inattentive and figity – symptoms that can be mistaken as symptoms of ADHD. This complexity does not make clinical diagnoses of mental disorders impossible, just difficult, and we are still left with using scientific evidence to make an individual decision about the reliability of a particular diagnosis.
Of all the mental disorders there seems to be the most public controversy around the diagnosis of attention deficit/hyperactivity disorder (ADHD). In my opinion this is due to the fact that this diagnosis is given to children – this triggers our basic protective parental instincts, as well as our casual judgmentalism about how other people should be raising their children. The most often alternative hypothesis offered to a biological cause for the symptoms of ADHD is simple bad parenting – people seem to like to blame the parents, which is also a back-handed way of congratulating themselves for being good parents. I find myself falling into this habit also, I am quick to assume that a bad kid means bad parenting, and I have to remind myself that genes have an important influence outside the control of parents.
So what does the evidence show about the specificity and sensitivity of the ADHD diagnosis? Well, there is a range of opinions expressed in published systematic literature reviews, some emphasizing the strengths of the diagnosis and others the weaknesses. This review published in JAMA represents, by my readings and discussions, the current consensus view. The authors write: “Diagnostic criteria for ADHD are based on extensive empirical research and, if applied appropriately, lead to the diagnosis of a syndrome with high interrater reliability, good face validity, and high predictability of course and medication responsiveness.” That sounds pretty good.
But, to be complete, here is a review representing the dissenter opinion. The single author, L. Furman, writes: “In summary, the working dogma that ADHD is a disease or neurobehavioral condition does not at this time hold up to scrutiny of evidence. Thorough evaluation of symptomatic children should be individualized, and include assessment of educational, psychologic, psychiatric, and family needs.”
It is difficult to summarize this complex issue, but I will give my interpretation of the weight of the evidence so far (from the perspective of someone who is not an ADHD expert but is an academic neurologist and skeptic). The diagnosis of ADHD is reliable enough to be a useful clinical entity. The current diagnostic criteria have good sensitivity, but still only OK specificity, largely because of overlap with other psychiatric disorders (more so than overlap with the healthy range of behavior, but this occurs also).
Also, it is critical to note that the diagnosis of ADHD is a rapidly moving target. Serious researchers are tackling the weaknesses of the diagnosis from multiple angles, trying new schemes, and trying to identify all the various wrinkles of what is really a range of disorders. We are also seeing researcher looking at ways to incorporate our increasing knowledge of the biological basis of ADHD. I found numerous studies, like this one that uses changes on EEG to enhance the clinical criteria and resulting in much greater specificity of diagnosis.
I do not think that laboratory testing will ever replace clinical diagnosis for ADHD or most mental illnesses – just like they haven’t in most of medicine. Most medical conditions are still diagnosed by symptoms and exam, and the diagnostic tests must be placed in the proper clinical context. The same is true of mental illness – but we will see an increasing use of biological tests to aid in the diagnosis of ADHD and other mental disorders.
The reality, transparent for anyone to see in the published literature, is a far cry from the caricature painted by Dr. Baughman – that the diagnosis of ADHD is a simple fraud perpetrated by the pharmaceutical industry conspiring with deceptive psychiatrists. Rather, this is a serious and fruitful domain of research in the academic setting. Also, the research is moving forward and creating tangible results – unlike the research done in truly pseudoscientific arenas, such as ESP, that seems to only go around in circles without ever making identifiable progress.
I had planned to address both diagnosis and medication therapy today, but since the first part went longer than expected I will address the medication question in tomorrow’s post.
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