What is DSM?

The Diagnostic and Statistical Manual of Mental Disorders, or DSM, has undergone at least three major transformations throughout its history. These fundamental changes usually occurred as a result of shifts in classification principles and basic concepts. Initially, before the development of its first edition, there was no clear principle or framework for defining mental disorders or psychological conditions, and professionals labeled others based on their personal opinions.

The WHO and APA are authoritative organizations that define the basic concepts and principles underlying different psychiatric and psychological classification systems, which are used in the DSM and ICD.

In this Blogpost, we will examine the fundamental concepts, principles, diagnostic criteria, and classification philosophy of the latest version of the DSM.

Definitions and Concepts

The first definition we need to address is the definition of a mental disorder. The definition of mental disorder in the 21st century has undergone three major changes, and the latest precise definition is as follows:

"A mental disorder is a syndrome (a collection of symptoms) that causes disruption in cognition, emotion, or behavior and creates distress, disability, or dysfunction."

(DSM-5; Introduction – page 26)

One of the greatest criticisms of the fourth edition of the DSM was the lack of a clear boundary between normal and abnormal behavior, or more generally, between healthy and unhealthy individuals.

The latest version of the DSM clearly defines this boundary:

"A mental disorder is an abnormal behavior that disrupts continuity and functioning. Every abnormal behavior is not a mental disorder."

(DSM-5; Introduction – page 27)

Based on this, we should reason that someone who is unable to fall asleep for one night does not have a sleep disorder. However, if for three months they have difficulty falling asleep or maintaining sleep at least three times per week, or are dissatisfied with their sleep quality, their problem is evaluated according to the criteria for sleep disorders.

Criteria for Mental Disorders

Throughout the history of clinical psychology, there have always been criteria for identifying mental disorders. Before these criteria were systematically examined, they were usually unclear, confusing, or biased. DSM-5 considers the criteria for mental disorders to be limited to characteristics that are present across all disorders. All diagnostic criteria for all mental disorders in the last two DSM editions have been developed based on these criteria.

They are as follows:

1- Deviation from Statistical Norms

According to this criterion, individuals who are located at the two extremes of a normal distribution and differ from the statistical average are considered abnormal. To better understand this, consider mood. Individuals with low mood (depression) and individuals with elevated mood (mania) differ from the statistical average and are considered abnormal. The important point is that deviation from statistical norms is not always connected with our perception of whether a deviation is good or bad.

For example, based on this criterion, individuals with IQ scores below 75 or above 125 are considered abnormal. (Basically, contrary to our intuition, abnormal does not always mean undesired or bad)

2- Deviation from Social/Cultural Norms

Deviation from social/cultural norms has always been one of the criteria for abnormality throughout the history of clinical psychology. Based on this criterion, all individuals who behave differently from the majority of their society are considered abnormal. The important point is that in the past this criterion was one of the most important criteria.

For example, enslaved Black people were expected to obey and follow their masters, and if an enslaved person wanted to escape and seek freedom, they could be considered abnormal and mentally ill! This biased perspective is changed in modern diagnostic criteria through various conditions to prevent abuse of mental disorder labels. Another important issue in this area is cross-cultural differences.

A person born in East Asia who has grown according to the cultural beliefs of their region may hold beliefs about the world that appear abnormal from the perspective of a Western individual. Conversely, Western beliefs about the world may appear deficient from the perspective of an Eastern individual.

The issue becomes more complicated when subcultures are included in the equation. A small group within a society may hold beliefs that are not accepted by others. In such situations, deviation from social norms does not have clinical significance. Simply put, deviation from social/cultural norms must be examined within the context of an individual's life.

For example, damning the devil after something bad happens is very common in different cultures. Believing or not believing in it has no particular clinical significance; however, if an individual becomes so dependent on this belief that their daily life is disrupted, it should be considered a form of culturally influenced magical thinking and given clinical importance.

3- Predictability

According to historians, after Pinel organized and improved the conditions for people hospitalized in psychiatric institutions, people were still afraid to approach them. This was because of the perceived unpredictability of these individuals. This criterion remains an important consideration. people usually behave in ways where expectations can be formed about their actions and reactions.

However, mental disorders may cause individuals to be less predictable. Unpredictability is often observable in individuals with schizophrenia or mania and exists to some degree in all of us. Very rarely this unpredictability cause actual danger; but nonetheless if affect the persons social relations.

4- Danger (Toward Self or Others)

Regardless of individuals’ personal beliefs, laws, and frameworks, any intentional harm toward oneself or others is an important criterion. Humans have a powerful drive and instinct for survival, and any violation of it should be considered clinically significant. (Do not confuse this with choices like euthanasia or assisted suicide)

For example, a person with depression who has suicidal thoughts, or a person experiencing psychosis who has homicidal intentions (which is actually rare), might both be considered abnormal because of the danger they pose to their own life or the lives of others.

An important point in this area is distinguishing the reason and meaning behind harm toward oneself or others. For example, someone who has experienced many negative events in life may view suicidal thoughts as a form of defense against further suffering. Such thoughts are not necessarily the opposite of the survival instinct; rather in serve of meaning.

5- Psychological Distress

Unlike much of the history of clinical psychology, in the modern framework psychological distress is the most important criterion for mental disorders. Humans may experience distress for many different reasons. A person with depression suffers; someone who loses a loved one suffers; someone who loses their job suffers. However, not all distress is a sign of disorder.

The condition for clinical significance is that the distress is disproportionate to the circumstances. For example, someone who loses a loved one naturally experiences distress, and someone who loses their job naturally experiences distress. However, only when the intensity or duration of this distress is disproportionate to the situation should it be considered clinically significant. judging it as disproportion should rely on cultural and subcultural norms too.

The importance of this point is that a percentage of individuals with mental disorders do not experience distress. For example, someone experiencing mania may not experience distress. In this person, too, the distress is disproportionate to the situation; therefore, it should be considered clinically significant.

6.1- Dysfunction

In the last four DSM editions (DSM-IV onward), dysfunction and/or disability were added as important conditions for diagnosis. It is proposed that all mental disorders produce at least one of these two outcomes to qualify for diagnosis.

Dysfunction, inefficiency, impairment, disruption in functioning, or any other term describing dysfunction refers to the consequences of a mental disorder. Mental disorders create problems in different areas of an individual's life, and diagnosis is confirmed only if these problems lead to dysfunction or disability; otherwise, the diagnosis is invalid.

DSM-5 introduces several exceptions for disorders involving lack of insight, where the consequences of the disorder appear differently in terms of dysfunction or disability.

6.2- Disability

Any deficiency in activity is considered disability. For example, just as we consider someone who has lost the ability to use their legs to have a disability, we should also consider a child with dyscalculia who cannot learn mathematics (like their typically developing peers) to have a disability.

Contrary to assumptions about disability, it does not necessarily mean a deficiency in intelligence, motor abilities, or perceptual skills. Any inability to use and demonstrate skills that peers possess, but the individual does not, is considered disability.

Difference Between DSM-5 Diagnostic Conditions and Previous Versions

The six criteria for distinguishing mental disorders and abnormal behavior from normal behavior existed approximately from DSM-III onward in all versions. However, a major change occurred in 2013 with the publication of DSM-5:

Distress and dysfunction and/or disability are the two main conditions for diagnosis. If all other criteria are present except distress and dysfunction, diagnosis is not confirmed. If only distress exists but dysfunction does not, diagnosis is also rejected.

DSM-5 repeatedly emphasizes that statistical deviation, social norms, or even the presence of other diagnostic criteria cannot confirm a diagnosis when distress and dysfunction and/or disability are absent.

To prevent complexity or failure to diagnose due to the interviewer’s inability to identify distress and dysfunction, DSM-5 suggests two approaches: If symptoms and signs are clear but distress and dysfunction are absent, the diagnosis should be recorded as a syndrome. If distress and dysfunction cannot be clearly inferred, the interviewer should record a provisional diagnosis until additional evidence is discovered.

To clarify, imagine someone who has all symptoms of ADHD, whose brain scans show functional abnormalities, and whose reports of daily life strongly indicates a problem, but the individual does not report distress or dysfunction. They may have learned how to manage and control their life despite their difficulties, or they may not recognize their distress and dysfunction due to secondary reasons. In this situation, the professional should either record the diagnosis as a "syndrome" and report the absence of distress and dysfunction in the clinical report, or record a provisional diagnosis and search for further evidence.

Why Do We Need Classification of Mental Disorder Diagnoses?

The first historical need to categorize "unhealthy" individuals occurred during the 1840 U.S. census. Approximately fifty years later, Emil Kraepelin decided for the first time to classify disorders and introduce the symptoms of each.

The U.S. government classification in 1840 included only two diagnoses: “insane” and “idiot.” Census officials mostly assigned the diagnosis of insanity to Black people and the diagnosis of idiocy to women.

Kraepelin’s classification included five diagnoses, which changed into seven within a decade with different descriptions. making it more rigorous, less likely to be misused and labeled. With the beginning of World War I, the U.S. government asked its specialists to establish criteria for distinguishing healthy soldiers from unhealthy ones.

Over time, as diagnostic manuals became established among mental health professionals and consensus developed around their use, particularly with DSM-III and ICD-8, these diagnostic guides became globally widespread.

Today, most people are familiar with mental disorders and apply labels to themselves or others. However, DSM discusses various aspects of using classification and diagnosis. From DSM-5 onward, the list of mental disorders begins with a legal warning regarding their use.

The most important benefit of diagnostic manuals under WHO and APA supervision (DSM and ICD) is creating specialized terms for communication between professionals. (meaning they should not be used outside of clinical setting at all) A clinical diagnosis contains information about a disorder.

For example, when one professional sees another professional’s diagnosis written as “paranoid schizophrenia,” they understand that the main issue involves increased dopamine activity in the patient’s brain. A clinical diagnosis also contains information about appropriate treatment methods. A second professional receiving a patient diagnosed with paranoid schizophrenia knows that dopamine antagonist medication may be required. A clinical diagnosis contains information for third parties. One party is professionals providing treatment, another is the patient requiring treatment, and the third is the government or insurance provider. When government agencies see a diagnosis such as paranoid schizophrenia, they know that certain social responsibilities, can not be expected. When insurance providers see such a diagnosis, they understand approximately how much time and cost treatment may require and what needs the patient may have.

Using diagnostic terms and manuals outside these three parties (professionals, patients, and government/insurance providers) have legal consequences. DSM particularly emphasizes this point to prevent stigma, bias toward symptoms (patients imitating expected symptoms), and especially violations of privacy.

APA guidelines clearly specify situations in which diagnoses should or should not be disclosed to patients. For some disorders and cases, it may be better for patients not to know their diagnosis; since it can arise (self)stigma. On the other hand, in some disorders it may be beneficial for patients to know their diagnosis. For example, a person experiencing anxiety may gain better control after learning about their condition.

Philosophy and Structure of DSM-5 Classification

The DSM-5 classification system is a complex multidimensional model that uses different classification principles at different levels. In this section, we examine different types of classification used in diagnostic manuals such as DSM and ICD.

1- Categorical Classification

Categorical classification was the method used before DSM-IV. In this system, to receive a diagnosis or belong to a category, an individual had to possess all characteristics of that category. Initially, both DSM and ICD used this approach, but problems existed.

For example, a patient might have all symptoms except one and therefore not receive a diagnosis or treatment. The weakness of categorical diagnosis is that it requires determining whether a person has disorder X or does not have it, while reality is not always this clear.

DSM and ICD still use this method, but its level has changed. In recent versions, diagnoses are not entirely based on categorical classification, but disorders with similar characteristics are organized into the categories.

For example, mood disorders, depressive disorders, personality disorders, and others are grouped based on shared characteristics.

2- Dimensional Classification

Unlike categorical classification, dimensional classification focuses on how much of a characteristic a person has. This method is quantitative, and the amount of a feature or symptom is represented by numbers or descriptive terms.

For example, some psychological questionnaires measure different levels of disorder characteristics, add the scores together, and confirm diagnosis if the score exceeds a certain threshold. Dimensional classification was added to DSM in its fifth edition (e.g. for autism spectrum disorder).

Based on this, certain conditions must be met for diagnosis, and individuals who receive the diagnosis are placed on a spectrum from 1 to 3. Autism spectrum levels are also described using terms such as mild, severe, and requiring substantial support.

Overall, dimensional classification is closer to reality. Humans are not zero or one hundred percent in different characteristics; we share relatively similar traits but differ in degree. So why did dimensional classification not completely replace categorical classification in DSM?

Two major reasons influence this: Not everything can be validly quantified. "Intelligence" can be measured through intelligence tests, but do these tests truly measure intelligence? Can love, loyalty, fear, or worry be quantified? Dimensional classification is more difficult to use. In a categorical system, after reviewing symptoms, diagnosis is confirmed or rejected and the professional’s work ends. In dimensional classification, after diagnosis is confirmed, the professional’s work begins. This means more time is required, which is a major obstacle for many reasons.

For example, parents of an autistic child may not have difficulty attending repeated appointments, but a person with depression may lack motivation to return multiple times.

3- Morphological Classification

Morphological classification is a standard classification method in biology. In this system, each category has a set of major traits and characteristics, while additional features may also exist.

For example, fishes differ greatly from one another, but their main characteristics are having scales, gills, and living in water. A fish would never be confused with a bird. Only a limited number of psychological disorders in DSM-5-TR and ICD-11 are introduced based on morphological classification.

So what is its application?

Morphological classification does not describe disorders themselves, but DSM uses morphological principles as a condition for confirming diagnosis in almost all disorders. Additionally, this system has two important applications:

Profile comparison: Some disorders and questionnaires allow creation of symptom profiles. By comparing an individual’s psychological profile with the profile of disorder X, diagnosis can be confirmed or rejected and severity can be determined.

Diagnostic tree: Diagnostic trees are essentially an output of morphological classification. Imagine encountering an animal whose species you do not know. A diagnostic tree provides a simple flowchart using yes/no questions that leads you to the answer.

For example: Does it have a backbone? Does it have feathers? Does it have fur? Each answer moves you closer to identifying the species.

Important Terms Specific to DSM-5 and DSM-5-TR

The concepts and terms used in DSM have been operationally defined since the fourth edition. Simply put, some words used in DSM do not necessarily have their common meaning; most are shared within academic texts, but some are truly unique. The most important include:

Prevalence: The percentage of people who have a specific disorder during a specific period.

(Example: In summer 2024, depression prevalence was 17%; meaning 17% of people met the criteria, regardless of whether they received it before summer or after summer.)

Incidence: The percentage of people who newly develop a specific mental disorder during a specific period.

(Example: In summer 2024, depression incidence was 6%; meaning 6% received the diagnosis during that summer for the first time.)

Sign: Objective and observable factors that can be measured and recorded.

(Example: Psychomotor retardation is a sign of depression.)

Symptom: Subjective factors reported by the individual or others that cannot be directly measured or observed.

(Example: Sadness is a symptom of depression.)

More than one thousand terms are explained at the end of newer DSM editions.

Specifiers and Subtypes in DSM-5

Specifier and subtype are more recent DSM-5 terms that indicate different forms of a disorder. Although both are used, a disorder usually has either a specifier or a subtype, not both.

There are exceptions. Specifier Different states of a disorder that are not necessarily opposite or contradictory. An individual may receive multiple specifiers for one disorder. Specifiers may refer to the most prominent symptom, severity, duration, remission period, or prognosis.

For example, a person with depression may receive the melancholic specifier based on the dominant symptom and the mild specifier based on severity. Note that multiple specifiers may be assigned for one disorder, but a specifier cannot be diagnosed without the disorder itself. In DSM-5, there is no “melancholia disorder”; rather, there is “major depressive disorder with melancholic features.” Subtype Like specifiers, subtypes indicate different forms of a disorder.

The difference is that subtypes are mutually exclusive or contradictory, and only one should be diagnosed.

For example, in sleep disorders, the advanced sleep phase type, delayed sleep phase type, or irregular type may be diagnosed.

Final Words

The changes and developments in the history of clinical psychology were mainly caused by shifts in classification philosophy and even basic concepts. Despite existing criticisms, DSM (Alongside ICD) is considered precise and valid compared to counterparts, and most mental health professionals worldwide prefer it over competing systems.