The following case is a published account of a typical person with obsessive-compulsive disorder (OCD).

The OCD started when he was about 7 or 8 years of age and has gradually got worse. When he was doing homework in secondary school he was checking again and again that everything was done. This made him lose a lot of time. As a child he used to have phobias of lifts and elevators and thunder and lightning. He got teased in throughout school, because of his anxiousness and behaviours. After finishing school he started working in a job, where he had to make sure that everything was clean and clear, that things were locked up when he was leaving. This made his job very difficult for him and as the OCD got worse he was not able to do his job anymore because he was much too slow. Also he used to have to stay longer hours to check that he had done his job right. He has to think about things in a certain sequence before getting up in the morning. This sequence might delay him for almost half an hour before he is able to get up. The sequence comes again about 3 or 4 times daily. He has to check various things over and over again. When he makes his bed he has to check that it is made in the right way. He has to check the taps are not dripping, making sure that things are empty, making sure that he has put away everything he should, making sure that he has turned things off, closing windows, checking pockets, counting money again and again, he keeps checking that the light is off. When he has a shower it takes him a very long time because he has to get his clean clothes and check them at least 5 times before he can take them into the shower. He has to shower himself in a certain sequence and when he is out of the shower he has to dry himself also in a certain sequence. If he gets interrupted he has to start all over again. This is very annoying for him but also very disabling. Sometimes when he has to check things he talks to himself or whispers to get it all sorted in his head. The thoughts make it difficult for him to concentrate. It also has an impact on his self-esteem; feeling useless, frustrated, irritated, stressed and nervous.

There are those who deny the behaviors above should be considered a disorder or treated as a mental illness. The recent release of the DSM-5 has brought the mental illness deniers out of the woodwork to endlessly repeat their refuted and distorted claims yet again.

Mental illness deniers demonstrate nicely the pattern of argument that is typical of denialism – their arguments are essentially the same as those of evolution deniers, global warming deniers, holocaust deniers, HIV deniers, or germ theory/vaccine deniers. If you want a recent example, just look at the comments to a recent post of mine.

There are a few denialist features worth pointing out. The first is the use of semantics to dance around obvious conclusions. Deniers charge that mental illness is completely arbitrary (in fact they often argue it is political), without any objective biological basis. This is demonstrably false. Many of the major recognized mental illnesses, like OCD, have demonstrable differences in brain function, clear negative outcomes, and often even genetic predispositions. This data, however, is population-based and is not very useful when applied to an individual.

There are various reasons for this. Mental disorders are clinical syndromes and are likely to be biologically heterogenous, meaning that there are likely several disorders lumped together into one clinical syndrome with overlapping symptoms. OCD, for example, has various types: contamination/cleaning, harm/checking, symmetry/ordering, and unacceptable thoughts/mental rituals. Hoarding used to be considered part of OCD, but in the DSM-5 it is considered its own disorder. Are these all the same brain malfunction manifesting in different ways, or different malfunctions manifesting in similar ways? Perhaps it’s a bit of both.

When scientists study the genetics of OCD they sometimes find that certain genetic variants correlate with OCD, but this is not consistent enough to form the basis of a diagnosis for treatment.

So – the deniers take a false-dichotomy/moving the goalpost approach. They say there is no biological basis for mental disorder. When evidence is presented for a biological (brain-based) basis, they move the goalpost and say that the evidence cannot be used for diagnosis, which is true but irrelevant. When we do get to the point where there is a consistent-enough biological cause of a mental disorder found, the deniers then say – well, that just means it’s a neurological disease, not a mental illness.

They semantically define out of existence the very thing they are denying – mental illness is not a brain disorder because all demonstrable brain disorders are neurological diseases and not mental illness, even when they manifest with disorders of mood, thought, or behavior.

What about the case presented above? Is that not a demonstrable mental disorder? No problem for deniers – that is just a “problem in living.” Sure, people have problems, you just can’t call them disorders because that’s “pathologizing.”

The final semantic game is to play off the inconsistent use of the term “disease.” There is no “mental disease” because disease requires biological pathology and the mind cannot have the kind of pathology that you can see under a microscope or in a lab test. This becomes a massive straw man. For most mental illness, like OCD, no one claims there is necessarily classic pathology. The “psychopathology” (the term sometimes used) is at the level of brain wiring. We are just now turning new technology (like fMRI scans) to map the brain’s wiring, and to see how this wiring is different in various mental disorders.

People with OCD tend to have hyperactive responses in the disgust circuit in the brain. Is this a disorder? Is hyperactivity in a brain circuit pathology?

You can play with semantic endlessly – the scientific facts are that mood, thought, and behavior is brain function, brain function can be different at the level of wiring and neuronal activity in a way that results in mood, thought, and behavior that is demonstrably harmful and often perceived by the person as harmful, unpleasant, and unwanted. This can be so far out of the range of what is typical and functional for people that it becomes absurd not to recognize the result as a disorder.

Another favorite logical fallacy of the denier is the false continuum. This is the flip side to the false dichotomy. In a false dichotomy logical fallacy a continuum or multiple possibilities are treated as if they break down into a binary choice – black or white with no shades of gray, or no reds or blues.

The false continuum logical fallacy is the argument that because there is a continuum, there is therefore no meaningful difference between the extremes. You cannot draw a sharp dividing line between tall and short, therefore it is meaningless to speak of people being tall or short. Kareem Abdul Jabbar is not tall, and Tyrion Lannister is not short.

There is no sharp dividing line between science and pseudoscience, a religion and a cult, normal and abnormal. That does not mean that these concepts are useless.

Human behavior simultaneously exists along multiple interacting spectrums. Further, inherent behavioral tendencies exist within a cultural and environmental context. So, yeah, there are no sharp lines of demarcation with mental illness. We are all a little obsessive-compulsive, a little paranoid, we all get depressed at times, and feel anxious. None of this means, however, that crushing persistent depression without apparent environmental cause is not a genuine disorder. The fact that I have a little symmetry/ordering bias doesn’t mean that people who become buried alive under their piles of horded trash don’t have a demonstrable disorder.


Denying mental illness is ultimately denying the brain. The brain is an organ, just like any other. It is very complex, and its function depends upon subtle features that we are just now able to image with any utility. Our knowledge of how brain function relates to thought, mood, and behavior is growing, and with it our knowledge of the reductionist basis of mental disorders.

Progress is slow and difficult because of the horrific complexity of the subject, but progress is also steady.

Mental illness deniers, however, deny this progress. They pretend as if we know nothing about the biological basis of mental disorders, until that knowledge gets to a practical and undeniable level and then they declare the disorder a neurological disease. In reality different mental illnesses are at various places along the continuum of knowledge into their biological basis.

When called on their logical fallacies and distortions they tend to retreat to the ultimate fortress of denial – “I’m just asking question,” “Is anyone who expresses any doubt about X a denier, then,” “I’m the real skeptic because I question the powers that be.”

Asking questions, doubting, and being skeptical are all virtues. But method and process matters, not labels.


Steven Novella, M.D. is the JREF's Senior Fellow and Director of the JREF’s Science-Based Medicine project.