What Is a Psychological Disorder?

Definition, Diagnosis and Prevalence

What exactly is a psychological disorder? How is a psychological disorder diagnosed? Defining exactly what constitutes a mental disorder can be tricky and, definitions have changed over time.

The first problem is that psychologists must first decide exactly how to define disorder. How do you determine if there is something psychologically wrong or unhealthy about a person? How do you decide what's normal and what's abnormal?

If you were to define disorder as something that lies outside of the statistical norm, then people who are considered exceptionally talented or gifted in a particular area would be regarded as abnormal. So rather than focus on actions that are considered outside of the normal statistically speaking, psychologists tend to concentrate on the results of those behaviors. Behaviors that are considered maladaptive and cause significant personal distress and interrupt daily functioning are more likely to be labeled as abnormal.

Today many psychologists agree that psychological disorders are characterized by both personal distress and impairment in multiple areas of life.

Learn more about how clinicians define and classify mental disorders and discover how many people are impacted by such disorders every year.

What Is a Psychological Disorder?

Psychological Disorders
Psychological disorders cause distress and impairments in functioning.. Trina Dalziel / Illustration Works / Getty Images

A psychological disorder, also known as a mental disorder, is a pattern of behavioral or psychological symptoms that impact multiple life areas and create distress for the person experiencing these symptoms.​​​

The latest edition of the American Psychiatric Association's diagnostic manual, the DSM-5, defines a mental disorder as:

"...a syndrome characterized by clinically significant disturbance in an individual's cognitive, emotion regulation, or behavior that reflects a dysfunction in the psychological, biological, or developmental process underlying mental functioning. Mental disorders are usually associated with significant distress in social, occupational, or other important activities."

The DSM-5 also notes that expected responses to a common stressor such as the death of a loved one are not considered mental disorders. The diagnostic manual also suggests that behaviors that are often considered at odds with social norms are not considered disorders unless these actions are the result of some dysfunction.

How are Psychological Disorders Diagnosed?

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The classification and diagnosis is an important concern for both mental health providers and mental health clients. While there is no single, definitive definition of mental disorders, some different classification and diagnostic criteria have emerged. Clinicians utilize the Diagnostic and Statistical Manual of Mental Disorders, published by the American Psychiatric Association, to determine whether a set of symptoms or behaviors meets the criteria for diagnosis as a psychological disorder. The International Classification of Diseases, published by the World Health Organization, is also frequently used.

What Is the Purpose of Getting a Diagnosis?

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While some people may avoid seeking a diagnosis out of fear of social stigma, getting a diagnosis is an essential part of finding an effective treatment plan. A diagnosis is not about applying a label to a problem; it is about discovering solutions, treatments, and information related to the problem.

How Prevalent Are Psychological Disorders?

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Relatively recent research has revealed that psychological disorders are far more widespread than previously believed. According to the National Institute of Mental Health (NIMH), approximately 26 percent of American adults over the age of 18 suffer from some diagnosable mental disorder in a given year.

The 1994 National Comorbidity Survey (NCS) indicated that 30 percent of respondents had experienced symptoms of at least one psychological disorder in the previous year. The survey also showed that nearly half of all adults experience some form of mental disorder at some point in their life.

The National Institute of Mental Health (NIMH) estimates that in 2014 there were approximately 9.8 million adults in the U.S. with a serious mental illness. NIMH defines serious mental illness as a mental, behavioral or emotional disorder diagnosable within the past year that meets diagnostic criteria specified by the DSM-IV. These disorders must also lead to serious impairment in functioning that limits or interferes with one or more major life activities.

A 2005 study replicated the National Comorbidity Survey and found that 12-month prevalence rates were approximately 26 percent among U.S. adults. Anxiety disorders represented the most common psychological disorders (18.1 percent), with mood disorders (9.5 percent), impulse control (8.9 percent) and substance-related disorders (3.8 percent) following.

What Are the Different Types of Mental Disorders?

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The DSM describes approximately 150 different psychological disorders, as well as disorders that fall under a category of similar or related disorder subtypes. Some of the prominent diagnostic categories include eating disorders, mood disorders, somatoform disorders, sleep disorders, anxiety disorders and personality disorders.

References

Kessler, R.C., McGonagle, K.A., Zhoa, S., Nelson, C.B., Hughes, M., Eshleman, S., & others. (1994). Lifetime and 12-month prevalence of DSM-III-R psychiatric disorders in the United States: Results from the National Comorbidity Survey (NCS). Archives of General Psychiatry, 51, 8-19.

Kessler, R.C., Chiu, W.T., Demler, O., Merikangas, K.R., & Walters, E.E. (2005). Prevalence, severity, and comorbidity of 12-month DSM-IV disorders in the National Comorbidity Survey Replication. Archives of General Psychiatry, 62(2), 617-627.

National Institute of Mental Health. (2008). The numbers count: Mental disorders in America. Found online at http://www.nimh.nih.gov/health/publications/the-numbers-count-mental-disorders-in-america/index.shtml#Intro.

National Institute of Mental Health. (2014). Serious mental illness (SMI) among U.S. adults. Retrieved from http://www.nimh.nih.gov/health/statistics/prevalence/serious-mental-illness-smi-among-us-adults.shtml.

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