How do doctors know if someone has a mental disorder or not? Who decides what should be categorised as a mental disorder or just normal behaviour? Two major organisations do this: the American Psychiatric Association and the World Health Organisation.
First, let's explain the classification of mental disorders.
Next, what are the benefits of labelling and categorising mental disorders?
Are there disadvantages to the classification of mental disorders?
Then, let's dive into two crucial diagnostic manuals: the DSM IV and ICD 10.
Finally, we'll discuss the psychiatric classification system's strengths and limitations.
6 Major Types of Mental Disorders
Many times, when we consider mental disorders or psychological disorders, it's (but not always) often in terms of abnormal behaviour. This perspective is also commonly used when categorising mental disorders or psychiatric nosology.
Psychiatric nosology is another name for the classification of mental disorders.
There are 6 major types of mental disorders:
| Category of mental disorder | Example mental disorder |
| Affective/ Mood disorder | Depression |
| Anxiety | Generalised anxiety disorder |
| Personality disorders | Borderline personality disorder |
| Psychotic disorders | Schizophrenia |
| Eating disorders | Anorexia nervosa |
| Trauma-related disorders | Post-traumatic stress disorder |
Substance abuse disorders are another major category of mental disorders.
Benefits of Labelling and Categorising Mental Disorders
There are several reasons why the classification of mental disorders is important:
It allows for an objective diagnosis of a disorder someone may have.
It shows symptoms of disorders to allow for easier identification of a potential disorder.
It can be used to identify potential research participants, e.g. participants with mental disorders.
It makes it easier to identify the support people with mental disorders need.
Clinical psychology research especially aims to identify if a treatment is effective by comparing intervention results in patients.
A major benefit of labelling and categorising mental disorders is that it provides clinicians with tangible information on how well a treatment is working or not working. If that information were inaccurate, it could lead to invalid results and ineffective treatments, which can be dangerous.
Fig. 1 - Categorising mental disorders can be helpful in finding the right treatment
Disadvantages of Classification of Mental Disorders
Are there disadvantages to the classification of mental disorders? Well, identifying the difference between normal and abnormal behaviour can be a challenging task. So much so that some psychologists have questioned the reliability of categorising mental disorders based on abnormal behaviours.
David Rosenhan (1973), a former psychiatrist at Stanford University, wanted to see just how well psychiatrists really could distinguish between normal and abnormal behaviours.
In his experiment, he sent eight "normal" psychologists to 12 mental hospitals, meaning none had a mental disorder. However, every one of the 12 hospitals diagnosed all of the fake patients with mental disorders.
Even in the follow-up study, when Rosenhan asked staff to rate the likelihood that one of the patients was a fake (healthy) patient, none of them was identified.
The staff did, however, identify 21.24% of the patients as fake patients when in fact, they were not.
Disadvantages of Classification of Mental Disorders: Cultural Considerations
There are also several disadvantages to classifying mental disorders when considering cultural differences.
When someone is diagnosed with a mental disorder and visits another country with a different diagnosis, problems arise, such as problems with getting medication. How does the person know which diagnosis is correct?
The manuals that categorise mental disorders may not be generalisable to the entire or diverse (minority) population, which suggests reliability issues. Some may rely too heavily on a professional's judgement which will influence their analysis. These opinions may differ depending on the culture of the professional, so the diagnosis may not be reliable.
This, however, could be advantageous in some situations where the professional's cultural background may allow them to identify mental disorders that a manual would otherwise miss (or vice versa).
DSM IV and ICD 10
Now, let's look at some modern examples of categorising mental disorders -- the DSM IV and ICD 10.
| Diagnostic and Statistical Manual for Mental Disorders (DSM-IV) | International Classification of Diseases (ICD-10) |
| Author | American Psychiatric Association (APA) | The World Health Organization (WHO) |
| Description | The DSM is a manual that trained therapists use to diagnose mental illnesses. This manual is widely used in America. The American Psychiatric Association (APA) developed and published the DSM. The DSM allows a common way to communicate disorders between psychiatrists. It has multiple editions revised based on advancements in our understanding of mental health. | The ICD is a manual that lists all known mental illnesses and their symptoms. Health professionals worldwide use it (except in America and some other countries). The ICD is translated into many languages, is relatively cheap, and is accessible to low-income countries. The F20.0 is a numerical coding system the ICD uses. This system codes and classifies all illnesses and diseases recorded by the ICD. |
| Current versions | DSM-5 | ICD-11 |
| Changes | No longer uses a multi-axial approach for categorising mental disorders as there were criticisms that they were artificial and made it difficult to find a link between different symptoms. It removed any unnecessary and overused diagnoses. It updated language with more inoffensive terms. Previous editions had the term' 'mental retardation'', which ''intellectual disability'' or intellectual development disorder now replaced.
| It contains 21 disorder groups. ICD-10 contained 11 disorder groupings. It added new diagnostic categories (i.e. grief, compulsive sexual behaviour, computer gaming), which changed existing diagnoses. Changes in coding There were six new chapters added The code for Alzheimer's disease:
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DSM-IV and ISD-10: Important Differences
There are some differences between the ICD and DSM, such as:
The ICD does not attempt to give operational criteria, whereas the DSM does.
The DSM typically has listed more mental disorders and associated symptoms than the ICD.
There are differences in symptoms of mental disorders.
In the DSM, some autism spectrum disorder (ASD) symptoms have to persist for at least six months for a diagnosis. However, the ICD does not give a time frame for how long symptoms must be experienced.
In a study by Wilson et al. (2013), 75% of participants met the criteria for ASD based on the revised version of ICD-10. In contrast, 42% of the participants were diagnosed with ASD when DSM-5 was used for diagnosis.
This shows that the DSM may be more restrictive than the ICD. Or, the DSM may be more precise at diagnosis. This finding cannot be identified if one is better than the other. The ICD symptoms of ASD may overlap with other mental disorders, so participants diagnosed may have other mental disorders. Or the DSM may be too restrictive.
Psychiatric Classification System Strengths and Limitations
Psychiatric classification systems are used throughout the world to diagnose mental disorders. However, different countries may use different classification systems. Let's explore the psychiatric classification system's strengths and limitations using the DSM and ICD as examples.
Psychiatric Classification System Strengths and Limitations: DSM
First, the strengths and limitations of the DSM.
Strengths of the DSM
First, the newer editions of the DSM have adjusted the listed mental disorders to consider social changes in society.
The DSM now separates mild and major dementia to consider that the average life expectancy has increased. Dementia is more likely to be diagnosed earlier, and people can get the required support earlier.
Another strength is that the DSM is regularly updated based on rigorously tested empirical psychology evidence. Updates ensure the manual is accurate.
Limitations
There are overlapping diagnostic symptoms of mental illnesses which results in co-morbidity.
Co-morbidity is when symptoms of two or more mental disorders are present in a patient simultaneously.
This can be a major problem because clinicians may diagnose someone with one disorder while missing another diagnosis entirely simply because the symptoms so closely resemble each other. As mentioned early, proper diagnosis can be integral to finding an effective treatment.
Fig. 2 - Categorising mental disorders is important because mental health matters
Another weakness is that since the American Psychological Association (APA) designed the manual, it can be considered ethnocentric. In other words, the manual may not consider cultural differences and may only benefit the American population.
Psychiatric Classification System Strengths and Limitations: ICD-10
Next, the psychiatric classification system strengths and limitations in ICD-10 will be discussed.
Strengths
The ICD-10 is a diagnostic manual that is free of charge. The manual is available for anyone, making mental health diagnoses easily and readily available to everyone worldwide, including third-world countries.
This can help reduce the block of mental health interventions not advancing in some countries.
Secondly, the manual lists all known diseases and illnesses, which helps clinicians identify diseases and illnesses of patients which may be less known.
Limitations
Some argue that a significant limitation of the ICD is that it is beneficial for identifying mental illnesses but not as much for determining the severity of symptoms (Hoffman et al., 2015). Additionally, the model takes the medical model approach to mental illness and ignores other alternatives, such as the humanistic or psychodynamic explanations.
Finally, the ICD considers that mental illnesses can be understood based on symptoms experienced but ignores important factors such as childhood experiences or self-actualisation factors.
Categorising Mental Disorders - Key takeaways
- The Diagnostic and Statistical Manual of Mental Disorders (DSM) and the International Classification of Diseases (ICD) are the two most common psychiatric classification systems.
- There are seven major types of mental disorders that have been identified.
- The ICD and DSM are diagnostic manuals that list known mental disorders and their symptoms.
- WHO designed the ICD for multiple countries. APA created the DSM for use in America.
- There are strengths and issues to the reliability and validity of the ICD and DSM.
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