An Analysis of Classification Systems 

To begin our series on mental health, it is important first and foremost to discuss the classifications of mental health disorders, both historically and modernly. This will allow us to understand how we have the diagnostic tools we use today and to judge the validity of these sources for providing an accurate picture of mental health for any researching writer.


The field of psychology is actually fairly new and constantly evolving. Beforehand, assumptions pertaining to mental health ranged from demonic possession to unbalanced humors, and treatment was often harsh and inhumane (Merges, 2019, Jan. 28). Gradually science began to take over, leading to all the theories discussed in your basic Psych 101 class: Psychoanalytic theory, Humanistic theory, Behavioral model, etc. I won’t go into those here but know that these various models were introduced and expanded on throughout the years by dozens of people, leading to the field of psychology as we know it today (Merges, 2019, Jan. 30).


Nowadays, psychologists use social, behavioral, and physical assessments to evaluate mental health (Merges, 2019, Feb. 4&6). However, assessing mental health isn’t quite the same as diagnosing say, a blood disorder. This is due to the ‘zone of rarity’ (Tyrer, 2014, p. 2). Professor Tyrer defines the zone of rarity as “the hiatus between the features of a biological disorder with a clear diagnosis and other conditions that do not carry this diagnosis” (Tyrer, 2014, p. 2). In essence, the gray area where the numbers don’t stack up quite enough to make a definitive diagnosis, but they’re close enough that a doctor can’t say for certain that the condition being tested for isn’t there. When analyzing things such as white blood cell counts, the presence of certain bacteria in samples, and other numerically quantified things, these clear numbers and ensuing zone of rarities can be seen. However, when a clinical assessment is based off anecdotal evidence, it becomes much harder to define these points. Enter the two main categorization manuals used worldwide: the DSM and the ICD.


The ICD, which stands for the International Classification of Diseases, is a manual published by the World Health Organization (WHO) which documents a wide range of disorders, both mental and physical (Merges, 2019, Feb. 4&6). It is the official manual used worldwide (with the exception of the US and a few others) that places a focus on clinical utility. The most recent version, the ICD-11, which will go into full effect of January of 2022, will be available entirely online for easier access. It has a much broader sample than the DSM, as the ICD examines samples from every country which submits data, whereas the DSM focuses on high-income countries. We will discuss the DSM later. For this reason, the ICD has a clear clinical advantage. When diagnosing mental illnesses, one must remember that mental illness must contain behavior that is disruptive and abnormal. But what is abnormal? It varies from place to place, culture to culture. The ICD keeps this in mind with a more dimensional approach to classification, and instead of telling us exactly what any mental health disorder looks like, it gives a general overview (Tyrer, 2014). Let us examine how the ICD-11 defines separation anxiety disorder (SAD):



(World Health Organization, 2019, p. 6B05)

As you can see, what we are given is a general overview of the disorder. Some commonly found symptoms of the disorder, the focus of it, and timeframe (World Health Organization, 2019, p. 6B05). Otherwise, the ICD-11 largely leaves the criteria up to the diagnosing physician, trusting them to be knowledgeable enough in their field to decide if a patient meets the criteria for the disorder.

The DSM series is what is used primarily in the United States but also in a few other countries and is based on data collected from high-income nations (Tyrer, 2014). This in and of itself presents an issue. By excluding medium and low-income countries, we have already lost a large population sample, thereby rendering the validity of the DSM-5 worldwide questionable. Also in contrast to the ICD-11, the DSM-5 gives specific criteria that a patient must meet in order to receive a diagnosis. Let us look again at separation anxiety disorder:


(American Psychiatric Association, 2013, pp. 190-191)

(American Psychiatric Association, 2013, pp. 190-191)

You’ll notice that where the description of the diagnosis overlaps between the two texts, the wording is practically identical. However, the DSM-5 lays out specific qualifications that a person must meet in order to receive the diagnosis of separation anxiety disorder (American Psychiatric Association, 2013, pp. 190-191). This reproduces results with incredible reliability in patients at the cost of validity. Yes, everyone who meets that criteria can commonly be agreed to have SAD, but this criterion eliminates patients who most likely do have the disorder, but due to the strict limits placed by the DSM-5, do not meet the diagnostic criteria and therefore cannot receive adequate treatment. Over the years the DSM series has become more dimensional, yet it remains too categorical for the comfort of many professionals. As Tyrer stated, “Increasingly, it has been recognized that a dimensional system of diagnosis is therefore superior to a categorical one, but this is only beginning to penetrate into diagnostic systems” (Tyrer, 2014, p. 3).

Now, there are many differing views in the field of mental health. Some clinicians believe the DSM-5 to be the superior classification system, due to its reliability, others feel that for the same reasons, the ICD-11 to be the better system. Still others advocate for the merging of the two systems (Tyrer, 2014). I am not an expert in the field of mental health. My highest education in the field is a Bachelors, and I have never treated a patient or had any real-world experience with either classification system. It is not my place to weigh in on which system is superior, though as you can imagine, I do have my opinions. So, let’s relate this back to the reason we’re all here to begin with- writing.

How is this relevant in writing? As we seek to write about mental disorders, we should always do our best to understand them and represent them as responsibly as possible. While the ICD-11 is perhaps too vague for someone without psychiatric training to really draw a good image of a disorder from (after all, its brevity is designed with fully educated physicians in mind) it is more inclusive overall. However, due to the DSM-5’s categorical classification, it perhaps paints a better (if not entirely accurate) picture of any one disorder than the ICD-11. Therefore, it is understandable that many writers conducting research would naturally draw more inspiration from the DSM-5 than the ICD-11. It is a great tool and can go a good deal toward providing examples of how a disorder may manifest, thereby providing us with good construction blocks when trying to build characters. The important thing to keep in mind, however, is that the examples given by the DSM-5 are not the only ways in which any mental health diagnosis may make itself known. Reading and analyzing the classifications of both the DSM-5 and the ICD-11 are, in my bold opinion, both very helpful in research. However, keeping in mind the rigidity of the DSM-5 and the brevity of the ICD-11, it is clearer than ever that for an aspiring writer, the best way to learn about any mental disorder is through talking to people.

Mental health impacts everyone in a vastly different way. How SAD, for example, manifests in one person will be vastly different than how it manifests in someone else, due to any number of factors. Only by talking to real people who are actually impacted by a disease can we really learn about it. Not just the clinical symptoms, but their effects on a person, their life, and the people around them. There is still so much stigma around mental health. If we look at it from only a scientific perspective, we lose the humanity that is equally necessary in the field. It is commonly said that psychology is both a science and an art, and so anyone hoping to understand it should treat it as such. Only then can we hope to treat the representation of such a harrowing topic with the humanity it deserves.

Merges, E. (2019, January 28). Historical perspectives on mental illness (I) [Lecture notes, Powerpoint slides].

Merges, E. (2019, January 30). Historical perspectives on mental illness (II) [Lecture notes, Powerpoint slides].

Merges, E. (2019, February 4; 2019, February 6). Clinical assessment and diagnosis [Lecture notes, Powerpoint slides].

Tyrer, P. (2014). A comparison of DSM and ICD classifications of mental disorder. Advances in Psychiatric Treatment, 20(Tyrer, 2014), 280-285. doi:10.1192/apt.bp.113.011296

World Health Organization. (2019). International statistical classification of diseases and related health problems (11th ed.).

American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.).

*Note: there is more to the DSM-5's description of this order than this. It goes into more depth regarding diagnostics, prevalence, and more. Please feel free to read the rest of the section elsewhere.*