One of the basic psychiatric principles accepted by all practicing psychiatrists is that a delusion is a fundamental symptom of psychosis.
A delusion is defined as “a fixed false belief not commensurate with the person’s educational and cultural background” and is almost universally associated with schizophrenia and other psychotic disorders. But if we apply the notion that a fixed false belief is delusional, then several “nonpsychotic” psychiatric disorders would qualify as psychoses based on their core clinical symptoms. Consider the following:
Major depressive disorder (MDD). The most prominent symptoms of MDD are feelings of “worthlessness” and “hopelessness.” Patients with clinical depression almost always believe—even if they are successful people—that they are failures, awful people, or a burden on their families. They also often believe that there is no hope for them, no way out of their rut and misery, and that death by suicide is the only option. Yet such patients—who clearly have reality distortion and who harbor a completely false view of themselves, the world, and the future—are not regarded as having a psychosis, but a standard depressive episode and are generally treated with antidepressants. Only when depressed patients express a paranoid idea or that their body is full of excrement or that God is punishing them for their evil acts are they given the diagnosis of “psychotic depression,” and an antipsychotic is considered a necessary adjunct to their antidepressant regimen.
But isn’t there just a dimensional difference in the severity of the delusion between MDD and psychotic depression? Shouldn’t worthlessness and hopelessness be regarded as psychotic symptoms congruent with the mood disorder? Interestingly, 2 atypical antipsychotics—aripiprazole and quetiapine—have been FDA-approved as add-on therapy for patients who do not respond to 1 or 2 antidepressants. Could the D2 dopamine antagonism exerted by antipsychotics be the reason for the stronger antidepressant response?
Obsessive-compulsive disorder (OCD). Is it not a fixed false belief when a person suffering from OCD washes his hands 50 to 100 times a day until his skin is raw because of the erroneous belief that his hands are dirty? Is it not psychosis when an OCD patient performs hours of daily rituals that render her dysfunctional because she falsely believes that unless she performs the rituals “something terrible will happen” to her or her loved ones?
Anxiety disorder. How about the reality distortion of anxiety disorder patients who would never board a plane because they falsely believe it will crash or will not drive over a bridge or in a tunnel because they believe it will collapse? Even when such false beliefs impair patients’ functioning, clinicians do not regard it as a psychosis but as “anxiety fear.” Is fear not the essence of paranoia?
Anorexia nervosa (AN). Is a severely emaciated AN patient’s fixed false belief that he or she is fat—which can be life-threatening—not a form of psychosis?
Body dysmorphic disorder (BDD). The completely unwarranted or fallacious perception of ugliness or blemishes in a BDD patient are a form of fixed false beliefs that may lead to functional disability or dozens of plastic surgeries. Regardless of whether a perceptual disturbance is involved, the phenotype qualifies as a psychotic disorder.
Hypochondriasis. When a person adamantly and falsely believes that he has a serious physical disease and expends time, effort, and money doctor-shopping to receive treatment for an illusory somatic ailment, why do we label it as a somatoform disorder instead of a somatic delusion? Interestingly, DSM-IV-TR criterion C of hypochondriasis specifies that the preoccupation of having a serious disease should not be of “delusional intensity (as in delusional disorder, somatic type).” What is the definition of delusional intensity? At what point does a false belief move from mild to intense status and becomes psychotic?
Personality disorders. Consider how various thematic false beliefs pervade several axis II disorders, such as paranoid, schizotypal, borderline, narcissistic, or avoidant personality disorders. They all have an enduring component of a fixed false belief that falls on the continuum of psychosis.
By now, some readers may have arrived at the conclusion that this editor has developed his own fixed false belief that practically all psychiatric disorders are psychotic! Well, not exactly, but I did intend to provoke you to reconsider what we take for granted in the DSM, where psychotic disorders are set aside as just one section of 17 types of disorders. At least I hope that I convinced you that a thread of psychotic thinking can be identified across many of the other 16 supposedly “nonpsychotic” groupings.