Commentary
Article
The Prism of Psychiatric Diagnosis
Author(s):
Struggling with complex psychiatric diagnoses? Consider the diagnostic prism.
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“All diagnoses are provisional formulae designed for action.”—Henry Cohen, MD, Professor of Medicine1
Case Study
Ms A is a software engineer, aged 40, who presents with a 10 year history of numerous psychiatric complaints, including but not limited to: flashbacks of a traumatic encounter when she was accosted by a man in a crowded elevator, difficulty sustaining attention at work, feeling “like I’m floating outside my body at times,” numerous periods of severe anxiety and depression, occasional binge eating, intrusive thoughts of harming herself, and great difficulty relating to male colleagues.
No doubt about it, psychiatric patients can be complicated, and so can psychiatric diagnosis. Indeed, the DSM-5 confronts the clinician with 20 major diagnostic categories, comprising nearly 300 specific disorders, depending on how one counts them.2, 3 So, what is the clinician to do when faced, for the first time, with a patient like Ms A? How likely is it that her symptoms can be explained by a single diagnosis?
This is a composite case, but, in my experience, not unrealistic in the context of outpatient psychiatry. I think many of us would have difficulty coming up with a single DSM-5 diagnosis—or even 2 or 3—that could comprehensively account for this clinical presentation. Indeed, the categorical structure of the DSM-5 does not lend itself to a fine-grained deconstruction of Ms A’s problems. This conundrum has led me, over the course of 4 decades in psychiatry, to devise a kind of diagnostic “prism” to aid the clinician evaluating a patient for the first time. I use this metaphor because of the prism’s refractive properties, such that a beam of light is separated into the colors of the rainbow. My diagnostic prism consists of 7 categories that represent the refraction of the patient’s clinical picture, allowing the clinician to gain a better understanding of her problems. (By sheer coincidence, there happen to be 7 primary colors in the visible spectrum.) At the same time, this set of 7 categories simplifies and condenses much of the content of the 20 main DSM categories, transforming them into a set of disturbances of function. With that prologue in mind, let’s take a look at the 7 functional—or perhaps we should say, dysfunctional—categories:
- Disturbances of reality perception (eg, delusions, hallucinations, flashbacks, derealization, brief psychotic episodes)
- Disturbances of memory, calculation, planning, or attention(ie, cognitive impairment)
- Disturbances of self-integration (eg, dissociative states, depersonalization, identity confusion, loss of ego boundaries, etc)
- Disturbances of mood quality, regulation, or stability (includes anxious, depressive, manic states, mood cycling, etc)
- Disturbances of behavioral self-regulation (eg, self-injury, violence, compulsions, pathological gambling, dyscontrol of appetite or substances/drugs)
- Disturbances of thought process, organization and flow (loose associations, disorganized thinking, intrusive thoughts, obsessions)
- Disturbances of interpersonal relations (antisocial tendencies, unstable relationships, “splitting,” exploitative behavior, etc)
The Prism Meets Occam’s Razor
These categories of disturbance are not intended to replace the 20 categories of the DSM-5; nor are they intended as comprehensive, etiology-based explanations of the patient’s presenting problems. In a sense, this diagnostic prism amounts to a prediagnostic deconstruction of the patient’s presenting problems, with the ultimate goal of developing a biopsychosocial case formulation and appropriate treatment plan.4 It is also important to note that these 7 categories do not map neatly onto specific DSM categories, and are indeed, trans-diagnostic with respect to categorical systems like that of the DSM’s. For example, a patient diagnosed with schizophrenia by DSM-5 criteria may show symptoms from category 1 (delusions, hallucinations); category 3 (loss of ego boundaries); category 6 (loose associations); and category 7 (unstable interpersonal relationships)—or, indeed, from all 7 categories. Going back to Ms. A, we can see that her symptom constellation spans the entire 7-fold spectrum—and I would suggest that this is not uncommon in clinical practice.
Now, to be sure, there are epistemic, diagnostic, and even therapeutic risks in seeing the patient’s problems through this sort of refractive lens. If used in isolation, this deconstructive, prismatic approach can obscure or conceal a single diagnostic entity that can parsimoniously and etiologically explain the patient’s clinical picture. This point harks back to the well-known Occam’s Razor, named for the medieval philosopher William of Occam (or Ockham, ca 1285-1348). Though Occam himself never used the term razor, we have come to apply that term to his thesis that, “plurality should not be posited without necessity”; alternatively, “entities are not to be multiplied beyond necessity.”5
For example, the single diagnosis of schizophrenia might well provide the best fit for the concurrence of paranoid delusions, command auditory hallucinations, loss of ego boundaries, loose associations, and other features noted in the DSM-5 criteria for schizophrenia. So too, a single, specific medical or neurological condition may explain the clinical picture fully; eg, tertiary syphilis masquerading as a functional psychotic illness.6 To employ Occam’s razor, the clinician may need to engage in a process of, so to speak, reverse refraction—analogous to the phenomenon in which, by passing the separated colors through a second prism positioned with the opposite orientation, the spectra of the rainbow are recombined, producing white light again. In effect, having separated the patient’s presentation into its component dysfunctions, the clinician must then ask, “Is there a single, well-defined disease entity that can account for this set of disturbances?” In my experience, it is often the process of toggling between these 2 methods—refraction and reverse refraction—that yields a more comprehensive understanding of the patient than either process alone. A quote often attributed to Albert Einstein sums it up well: “Everything should be made as simple as possible, but not simpler.”7
Treat the Disease Whenever Possible
To be clear, an excessive focus on individual symptoms or functional deficits risks missing the diagnostic forest for the trees; that is, conceptualizing the patient’s condition symptomatically rather than uncovering the underlying disease. As my colleague, Nassir Ghaemi, MD, has reminded us, “Scientific medicine is the treatment of diseases, not symptoms.” Indeed, Ghaemi points out that this is also the nature of Hippocratic medicine.8 That said, it is unfortunately the case that in both psychiatry and general medicine, we often find ourselves unable to identify a single underlying disease entity that accounts for the patient’s clinical picture. As family physician Kirsti Malterud, MD, has rightly observed, “…a clear and clean linearity between clinical phenomena, the names we can give them, and a subsequent rational treatment is the atypical exception rather than the norm in clinical medicine.”9
In ambiguous cases, it is helpful to identify specific functional deficits that can be ameliorated by careful, conservative, symptomatic treatment.In my experience, the diagnostic prism can be a useful tool in guiding such treatment. For example, in the hypothetical case of Ms A, we might well recommend some type of interpersonal psychotherapy to address her putative difficulty relating to male colleagues, while at least considering pharmacotherapy for her periods of severe anxiety and depression. Of course, we would need much more detailed information to determine the nature and optimal treatment of her problems.
Future Directions
I am hopeful that clinicians will test drive this 7-fold model in their own practice, particularly when first assessing a patient with a multiform and complicated spectrum of psychopathology—someone, say, like Ms A. I can even envision developing the prism into a quantitative screening instrument, such that the patient’s functional deficits can be scored in each of the 7 domains of psychopathology. Indeed, the prism is nothing if not a way of anatomizing a wide variety of psychopathology, preparatory to reaching a diagnosis, creating a biopsychosocial case formulation, and devising an appropriate treatment strategy. I hope to hear from colleagues who wish to share their experience with this potential new diagnostic tool.
Acknowledgement: I would like to thank Dr. Awais Aftab for his helpful comment during the early development of this article.
Dr Pies is Professor Emeritus of Psychiatry and Lecturer on Bioethics and Humanities, SUNY Upstate Medical University; Clinical Professor of Psychiatry, Tufts University School of Medicine; and Editor in Chief Emeritus of Psychiatric Times (2007-2010). Dr Pies is the author of several books. A collection of his works can be found on Amazon.
References
1. Cohen H. The nature, methods and purpose of diagnosis. Lancet 1943;24(6227):23-25.
2. Regier DA, Kuhl EA, Kupfer DJ. The DSM-5: classification and criteria changes. World Psychiatry. 2013;12(2):92-98.
3. Peterson TJ. The DSM-5: the encyclopedia of mental disorders. Healthy Place. October 23, 2019. Accessed January 17, 2025.
4. Ruffalo ML, Pies RW. Psychiatric diagnosis 2.0: the myth of the symptom checklist. Psychology Today. June 14, 2020. Accessed January 17, 2025. https://www.psychologytoday.com/us/blog/freud-fluoxetine/202006/psychiatric-diagnosis-20-the-myth-the-symptom-checklist
5. Duignan B. Occam’s razor. Encyclopædia Britannica. January 16, 2008. Accessed January 17, 2025. https://www.britannica.com/topic/Occams-razor
6. Nutile LM. Neurosyphilis With Psychosis as the Primary Presentation. American Journal of Psychiatry Residents' Journal. Published online March 12, 2021.
7. quoteresearch. Everything should be made as simple as possible, but not simpler. May 13, 2011. Accessed January 17, 2025. https://quoteinvestigator.com/2011/05/13/einstein-simple/
8. Ghaemi SN. Hippocratic psychopharmacology for bipolar disorder—an expert's opinion. Psychiatry (Edgmont). 2006;3(6):30-39. https://pmc.ncbi.nlm.nih.gov/articles/PMC2991080/
9. Malterud K. Diagnosis–a tool for rational action? A critical view from family medicine. Atrium. 2013;11:26-31.
