What is a psychological disorder: Definition and Differentiation

A psychological disorder is a relatively consistent condition over time expressed in forms of disturbance in cognition, emotional regulation and/or behavior. It is most likely inappropriate and harmful to an individual’s personal and social life in a given social and/or cultural context. The causal relationship between a mental condition and its related psychological, biological and developmental dysfunction can be bidirectional. The definition of a psychological disorder shall aim to be both exclusive and inclusive. It is inclusive in that it applies to a variety of clinical conditions with heterogeneity in manifestations. At the same time, it is also exclusive in that it differentiates conditions that are distressing and disabling yet socially or culturally explainable. It excludes conditions that have been stigmatized as queer or abnormal due to institutional oppression. It does not include temporary conditions of dysfunction caused by medication or other forms of substance misuse.

The differentiation between disordered and non-disordered states will not be achieved easily through mere observation. Nor will the description of a disorder be universally or permanently applicable. A psychological disorder is by all means a human condition that evolves along with the human kind. It is therefore crucial to stick to a set of guiding principles that informs the development and refinement of differentiation process. I hereby introduce the following four principles that could be optimally useful for not only clinical assessment, but also areas of treatment and research.

First, I want to point out the principle of interactivity between the definition of a psychological disorder and its diagnosis. I align myself with what Van Loo and Romeijin (2018) proposed as the double role of concept, which suggested that the criteria of a psychological disorder should not be used as a mere index for diagnosis. The criteria should also be taken as tentative defining features for the disorder until proven insufficient or inaccurate. It seems almost inevitable to examine something and describe its features while simultaneously revealing partially its nature if not all. For instance, as one lists the major depressive and manic episodes as observable diagnosis criteria for Bipolar Disorder, one also forms a defining statement of the disorder itself. Definition and criteria can thus be understood as a communicative entity, in which the criteria enrich but also simultaneously produce the definition. After all, an effective definition of a psychological disorder is not merely a label but instead a statement that offers directional insight in analyzing the condition. A disconnection between criteria and definition, on the other hand, poses challenges for accurate diagnosis that are crucial to treatments. For instance, in the previous DSMs, the diagnostic criteria of Special Language Impairment are met when children whose cognitive skills are within normal range display language impairment with no other identifiable reasons. The absence of specificity in the “what is” for SLI resulted in a widened spectrum of linguistic profile. Children “without” diagnosable Autism Spectrum Disorder, Down’s syndrome or other neurodevelopmental disorders fell into the group of SLI. The category became a convenient label for researchers with its classification unacceptably arbitrary (Reilly, 2014). The word “specific” in the name of the condition also prevent patients to access certain speech therapies. Children were denied treatment for not having the specific impairment or were no impaired enough to qualify therapies. The diagnostic dilemma of labeling something as “not others” was improved when DSM-V expanded the original term into the broader category “Language disorder” and adopted inclusionary criteria that took into account the fluid nature of language development up till pre-school (5th ed.; DSM-5; American Psychiatric Association). To achieve more accurate differentiation between disordered states, it is thus important to look at diagnosis criteria and the definition of a disorder holistically instead of in segments.

Second, as one begins to differentiate between two or more psychological disorders, it’s almost habitual to compare symptoms with pre-written criteria based on empirical studies. A set of criteria is a reflective connection between the disorder and what has been found so far about the condition. I therefore support an indexical view of psychological disorders, proposed by Kendler (2017), which encourages researchers and practitioners to see a mental condition beyond what is written in the current diagnostic handbook. Kendler reiterated that criteria for DSM-III were selected from a broader pool of possible symptoms and signs. Therefore the criteria were not constructed to exhaust the nature of a condition. In contrast to the constitutive view of a psychological disorder, indexical stance does not equate a disorder with its diagnostic criteria and allows for diversity in the manifestation of a condition. While Eating Disorders might express symptoms including food restriction among female patients, male patients could have the same condition but in forms of excessive exercising or disproportional protein supplement use(Murray et al., 2017). An indexical stance also acknowledges the fuzziness differentiating one disorder from another. A patient with tic disorder can display similar symptoms of repetitive, unwanted behaviors as a patient with obsessive compulsive disorder does. The intentionality and the function of the behaviors might not always be conspicuous, making it impossible to definitively claim that one is different from the other(5th ed.; DSM-5; American Psychiatric Association). With regard to the risk of being misdiagnosed and the risk of being denied resources given the improper diagnosis, it’s only reasonable for clinicians to be cautious upon calling something “novel” before fully exploring the possibility of multifinality. As for clinical research, one criticism of the DSM-V is that emerging findings do not always map well with existing categories of disorders. This is not only caused by a delay between research publishing and the update of the volume but also the failure of interpreting the latest research against the DSM indexically. A consequential phenomena detrimental to the refinement criteria was the rejection of promising findings that did not align with the current heterogeneous categories of symptom clusters (Cuthbert and Insel, 2013). The never-ending pursuit of the next reasonable goal in diagnosis and treatment is a common theme in the field of psychiatry. The principle of indexicality in the process of differentiation allows for improvement and will eventually lead to accumulation of more accurate knowledge of existing conditions in the coming days.

However, the necessity of a new set of measurements does occur when significant evidence against inclusion into an existing category comes into being. The third important principle is therefore a nuanced balance between specificity and sensitivity in diagnostic measurement. On the one hand, a highly sensitive measurement would benefit disorders for which early interventions make a big difference. On the other, a sensitive measurement could pick up too many individuals as possible cases so that the majority might risk having a false positive diagnosis that could later manifest into scientifically unfounded panic. Similarly, a measurement with high specificity could help the development of a more precise treatment. Yet, an overly specific criteria could also potentially rule out deserving patients whose conditions are not presenting to the necessary levels despite some quantitative or qualitative evidence. To decide between these two qualities of a measurement adopted in the clinical field is a continuous project that will not be achieved without compromises and struggles. It would indeed vary case by case not only based on the conditions of disorders, but also on the overall accessibility of the treatment. Therefore, I think it is important to think of criteria as “for” a disorder rather than “of” a disorder so that patients with the disorder will neither be equated with sets of symptoms and signs, nor will they be distant from what has been affecting their lives (Trumbetta, 2020).

As one proceeds in identifying a certain psychological disorder and attempts to locate the cause(s) of the condition, it is important to follow the final principle of multi-causality that acknowledges the complexity of a condition. The core of this principle is that no single variable could be confidently attributed as the singular cause of a psychological disorder. It’s not only impossible to remain unicausal in the field of psychology, the process of seeking for one single cause is also limiting for scientific research and detrimental to diagnosis. If one were to only aim for the so-called “essence” of a condition in treatment (i.e. the essentialist view point), one would most likely become disrespectful to personal experience of the patients. Dialogues with patients in access to their thoughts would become unnecessary or labeled as random once the essence is located. This will result in not only a non-humanistic approach towards the patients but also a stagnation in scientific exploration that contently sits on the past with a premature view of epiphenomenalism which has already been proven insufficient (Kendler, 2005). Furthermore, remaining unicausal also hinders the precision of treatment methods that tackles the specificity of individual cases. A patient might be unresponsive to existing treatment for a psychological disorder given his or her unique genetic and/or environmental background that has not yet been fully researched. Under a unicausal framework, not only does the patient risk not receiving effective treatment, he/she might even be considered untreatable and thus hospitalized or overly medicated for the rest of the life.

In contrast to an essentialist point of view, Kendler (2011) on exploring the philosophical meaning of a “kind” of disorder, pushed forward a mechanistic property cluster (MPC) theory for mapping psychological disorders. MPC borrowed its inspiration from statistics and maps out clusters of inter-related similar symptoms that could potentially be mutually causal. The core of MPC in clinical psychology is to use some degree of idealization and abstraction to locate patterns of complex interaction between behaviors, environment and genetics that allows for prediction, explanation and control of the myriad expression of the same kind of psychological disorder. The mechanism adheres to not only the multi-causal principle I identify with but also encourages collaboration in defining, diagnosing and treating a disorder. For instance, collaboration is prevalent among pediatrician, social workers, psychiatrists, behavioral or language therapists at an intervention program for children with Autism Spectrum Disorder, each complementing the knowledge of others. A pediatrician might examine the medical history for compromising health conditions while social workers assist the delivery of service in the community. A child receives optimal treatment when the intervention plan is tailored specifically to the child’s need and deficiency. Treatments might differ regionally in the details but display similarity in general focuses, which assimilates MPC in the clustering and the heterogeneity.

Finally, referring back to the definition of a psychological disorder stated in the very beginning of this article, I want to clarify my thoughts on the social constructivist point of view. Though in favor of an instrumentalist perspective in terms of treatment and intervention, I do not devalue the conversation around the philosophical definition of a psychological disorder. The perspective itself addressed crucial questions in almost all fields of scientific research. From the analogy Phillip et al. (2012) provided, it is obvious that the power of calling the ball and strike has never been shared across the variety of social status. It’s always in the hand of the umpire. The existence of a power dynamic in the social and culture context should not be the reason for us to reject the attempt of defining (i.e. Don’t call balls and strikes because the system is not fair) but should instead be seen as a caution of how a definition might inevitably be biased based on our social situatedness. The purpose for differentiation is not to institutionalize the oppression faced by minority groups under any circumstances. It’s therefore the most important for researchers and clinicians to keep in mind that differentiation stems from the intention to alleviate harm individuals with psychological conditions and their significant others suffered. A disorder does not exist without the existence of its beholder. In conclusion, I don’t consider the social constructivist theory in opposition to pragmatism, but rather think of them as crucial critical thoughts that advanced the field of psychiatry from different dimensions.

References

American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.). https://doi/org/10.1176/appi.books.9780890425596

Cuthbert, B.N., & Insel,T. R. (2013). Toward the future of psychiatric diagnosis: The seven pillars of RDoC. BMC Medicine, 11(1), 126. http://10.1186/1741-7015-11-126

Kendler, K. S. (2005). Toward a philosophical structure for psychiatry. The American Journal of Psychiatry, 162(3), 433-440. http://dx.doi.org/10.1176/appi.ajp.162.3.433

Kendler, K. S., Zachar, P., & Craver, C. (2011). What kinds of things are psychiatric disorders? Psychological Medicine, 41(6), 1143-1150. http://dx.doi.org/10.1017/S0033291710001844

Kendler, K. S. (2017). DSM disorders and their criteria: How should they inter-relate? Psychological Medicine, 47(12), 2054-2060. http://dx.doi.org/10.1017/S0033291717000678

Murray, S. B., Nagata, J. M., Griffiths, S., Calzo, J. P., Brown, T. A., Mitchison, D., Mond, J. M. (2017). The enigma of male eating disorders: A critical review and synthesis. Clinical Psychology Review, 57, 1-11. http://dx.doi.org/10.1016/j.cpr.2017.08.001

Phillips, J., Frances, A., Cerullo, M. A., Chardavoyne, J., Decker, H. S., First, M. B., Zachar, P. (2012). The six most essential questions in psychiatric diagnosis: A pluralogue part 1: Conceptual and definitional issues in psychiatric diagnosis. Philosophy, Ethics, and Humanities in Medicine, 7, 29. http://dx.doi.org/10.1186/1747-5341-7-3

Reilly, S., Tomblin, B., Law, J., McKean, C., Mensah, F. K., Morgan, A., Wake, M. (2014). Specific language impairment: A convenient label for whom? International Journal of Language & Communication Disorders, 49(4), 416-435. http://dx.doi.org/10.1111/1460-6984.12102

Trumbetta, S. (2020).Research Method in Clinical Psychology [Class Notes]

van Loo, H. M., & Romeijn, J. (2018). Letter to the editor: Measuring and defining: The double role of the DSM criteria for psychiatric disorders. Psychological Medicine, 48(5), 872-873. http://dx.doi.org/10.1017/S0033291717001799

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