What’s a Psychiatric Disorder?

Psychiatric disorder, or mental disorder, or mental illness (depending on who you ask) is a relatively contentious definition in the field of psychiatry.

The Diagnostic and Statistical Manual of Mental Disorders (DSM) is a widely used classification system of psychiatric disorders that was first published in 1952 by the American Psychiatric Association (APA). Since then, there have been nine follow-up editions in total, each edition reflecting the changing landscape of the field of psychiatry, and its approaches to studying, diagnosing, and treating conditions affecting mental health.

• DSM-I, the original edition, published in 1952
• DSM-II, major update, published in 1965
• DSM-II, 6th printing change, published in 1973
• DSM-III, major update, published in 1980
• DSM-III-R, revised IIIrd edition, published in 1987
• DSM-IV, major update, published in 1994
• DSM-IV-TR, text revision to IVth edition, published in 2000
• DSM-5, major update, published in 2013
• DSM-5-TR, text revision to 5th edition, published in 2022

The number of changes from initial edition to the current, DSM-5-TR, edition is significant and could make an entire book in and of itself. Nonetheless, we will focus on its most recent edition when discussing psychiatric disorders, unless the evolution of the DSM itself is a topic of interest.

Without digressing much further, the reason why I bring up DSM before even beginning to discuss terminology related to psychiatric disorders is because that manual exerts the most influence on how clinicians and scientists approach psychiatric disorders in their professions every day. 

For that reason, understanding the influence of DSM and APA on how psychiatric disorders are frames, conceptualized, diagnosed, and treated is essential to understanding much of today’s science in the field of psychiatry, and much of this blog.

So, back to our current topic: what’s a psychiatric disorder?

DSM-5-TR, provides a generalized definition for mental (psychiatric) disorder as follows:

A mental disorder is a syndrome characterized by clinically significant disturbance in an individual’s cognition, emotion regulation, or behavior that reflects a dysfunction in the psychological, biological, or developmental processes underlying mental functioning. Mental disorders are usually associated with significant distress or disability in social, occupational, or other important activities. An expectable or culturally approved response to a common stressor or loss, such as the death of a loved one, is not a mental disorder. Socially deviant behavior (e.g., political, religious, or sexual) and conflicts that are primarily between the individual and society are not mental disorders unless the deviance or conflict results from a dysfunction in the individual, as described above.

DSM-5-TR

There are several critical elements to APA’s definition worth discussing here, as these elements were essential in curating the DSM classification system and disorder definitions and diagnostic criteria.

The definition begins by emphasizing that mental disorder is a syndrome characterized by clinically significant disturbance in an individual’s cognition, emotion regulation, or behavior. This is a critical element specifying that mental disorders may be due to cognitive disturbances, emotion regulation disturbances, behavior disturbances, or any combination of the three.

Some disorders are characterized only by one type of a disturbance (e.g., behavior disturbance seen in pica), whereas others have a more complex presentation (e.g., cognitive, emotion regulation, and behavior disturbances in anorexia nervosa). If you asked an average person what a psychiatric disorder would be, they would likely provide some form of this sentence. However, as we can see in the DSM’s definition, there is a lot more to it.

Another key feature of this element is that this disturbance needs to be clinically significant. Elsewhere in the DSM-5-TR, the authors briefly explain that the clinical significance criterion is meant to supplement the absence of clear biological markers and clinically useful severity measurements for many mental disorders.

Diagnostic biomarkers are important in aiding the successful diagnosis of medical conditions. For example, glycated hemoglobin (HbA1c) is one of the most used biomarkers to diagnose diabetes. It forms when glucose (a sugar molecule) attaches to hemoglobin (a red blood cell protein that carries oxygen), and the level of HbA1c is proportional to the blood glucose level. 

Because high glucose levels should induce insulin release in the blood, the level of HbA1c is normally low. However, in people who suffer from diabetes, the body does not release enough insulin or use it properly to help process all the glucose, which is why its level gets high, and so does the level of HbA1c. Therefore, we can consider the level of HbA1c a diagnostic biomarker of diabetes.

Unfortunately, such tests do not exist for most psychiatric disorders, at least not with comparable specificity and sensitivity, making their diagnosis much more difficult. APA introduced the clinical significance criterion to allow clinicians to use their expert judgment to determine if the cognitive, emotion regulation, or behavior disturbances patients experience cause significant impairment in their daily function.

As a clarification for the clinical significance specifier, APA also provides that mental disorders are usually associated with significant distress or disability in social, occupational, or other important activities. In other words, the symptoms must be severe enough to affect one’s everyday function. 

For example, younger individuals with rumination disorder may begin to avoid eating breakfast, missing school, or stop participating in extracurricular activities because of an embarrassment or anxiety associated with regurgitating behavior.

However, the effects of disorders may have a more profound impact to person’s health, for example, individuals with pica might suffer an obstruction, poisoning or infection due to behavior disturbances. 

Similarly, individuals with anorexia nervosa may show evidence of leukopenia (low white blood cell count), anemia (low red blood cell count), thrombocytopenia (low platelet count), dehydration and other abnormalities in blood chemistry, as well as bradycardia (low heart rate), or amenorrhea (absence of menstrual periods).

Another core element to the definition is that these disturbances should reflect a dysfunction in the psychological, biological, or developmental processes underlying mental functioning. This part of the definition is very interesting, though understandably necessary. It specifies that mental disorders are indeed disturbances due to underlying biomedical processes and not social, cultural, religious, or spiritual contexts. 

While for most psychiatric disorders, we might not fully understand the exact underlying psychological, biological, and developmental processes, they do exist, nonetheless.

For example, twin and family studies have demonstrated a presence of genetic effects in a number of disorders. Such evidence of genetic effects points at biological origins or contributors to the risk of developing such disorder. We will talk about genetics of psychiatric disorders in much more detail in the future.

Considering cultural context is very important when diagnosing psychiatric disorders, and particularly feeding and eating disorders. APA specifies in their definition of mental disorder that an expectable or culturally approved response to a common stressor or loss, such as the death of a loved one, is not a mental disorder. 

In the context of feeding and eating disorders, pica may provide a good example. One of the common practices among the pregnant women (if we consider pregnancy a common stressor) in rural Tanzania, also known as the Chagga women, is geophagy (earth eating).

While geophagy is indeed a behavior disturbance symptomatic of pica, and pica is highly prevalent among pregnant women, in this particular case, I would argue that geophagy is a culturally approved (and perhaps even expected) behavior, thus, by the very definition of mental disorders (and, as we will later learn, diagnostic criteria for pica), the Chagga women engaging in geophagy do not suffer from pica.

Finally, APA specifies that socially deviant behavior (e.g., political, religious, or sexual) and conflicts that are primarily between the individual and society are not mental disorders unless the deviance or conflict results from a dysfunction in the individual, as described above. Here, we will consider anorexia nervosa and hunger strikes. Hunger strikes are a common tool employed by human rights activists as a form of political protest.

Let’s consider the example of Chanu Sharmila, and Indian activist who is known for her 16-year long hunger strike protesting an act which allows Indian armed forces to use deadly force if there is a “reasonable suspicion” that a person is acting against the state. Sharmila was even arrested several times for attempting suicide by means of a fast and force-fed while in custody through a nasogastric tube.

As this example shows that extreme fasting (restrictive eating behavior) is a socially deviant political behavior and a conflict between an individual and government, as opposed to a dysfunction of psychological, biological, or developmental processes, Sharmila did not suffer from anorexia nervosa during her hunger strike.

Anorexia nervosa is defined by three specific diagnostic criteria, two of which relate to fears, behaviors, or perceptions related to body weight or shape. Conversely, anorexia as a symptom is simply indicative of loss of appetite, or restrictive eating behaviors. 

Anorexia is thus a frequent symptom in individuals with cancer diagnosis (up to 1/3 of them) and is usually a complication of cancer or cancer-related treatments, medical procedures like bariatric surgery, and not necessarily a process underlying mental functioning.

Thus, diagnosing individuals with low body weight and restrictive eating behaviors and the absence of body shape and size related affective or behavioral symptoms with anorexia nervosa and not anorexia would be inappropriate.

Differential diagnosis in psychiatry is a complex task. Distinguishing psychiatric disorders from each other, or from non-psychiatric medical conditions may at times prove to be rather difficult. Entire branches of psychiatry are dedicated to developing tools to aid better, more accurate diagnosis of psychiatric disorders.

Nonetheless, defining what psychiatric disorder means, albeit a controversial exercise in and of itself, felt like a good starting point for this blog.

Featured image credit: TotumRevolutum.