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How to Diagnose Mental Disorders

The diagnosis of a mental disorder is a process that begins with a qualified licensed practitioner. Mental disorders are unique medical conditions because there are no laboratory tests that can be administered in order to help the clinician make an accurate diagnosis. This complicates the process and allows for more erroneous diagnosis than other types of medical conditions. To help clinicians avoid such errors, classification systems have been developed utilizing common nomenclature. Such nomenclature enables clinicians to effectively communicate with one another in a specific manner, resulting in better overall treatment of a patient. The two most widely used psychiatric classification systems are the International Classification of Disease System (ICD)and the Diagnostic and Statistical Manual of Mental Disorders (DSM). In the United States, the DSM is used as the standard diagnostic tool.

International Classification of Disease System (ICD)

The International Classification of Diseases (ICD) is published by the World Health Organization(WHO) and used worldwide for morbidityand mortality statistics, reimbursement systems, and automated decision support in medicine. This system is designed to promote international comparability in the collection, processing, classification, and presentation of these statistics. The ICD is a core classification of the WHO Family of International Classifications.


The American Medico-Psychological Association (which is now called the American Psychological Association) first attempted to publish a manual containing common nomenclature in 1918 called Statistical Manual for Use of Institutions for the Insane, however, it failed because it was poorly constructed. Another edition was published in 1928, but again failed, this time because it was too narrowly focused. In 1948, WHO issued the ICD-6 and was moderately successful in European countries. Finally in 1952 the APA published it's first manual successfully and have continued revising ever since. DSM-I: The first edition of the DSM was published in 1952 by the American Psychological Association (APA). This first edition was based off of the previously published ICD-6 and an independent nomenclature system developed at the beginning of WWII by the military. While the DSM-I gained acceptance in the United States and Europe, it was still criticized for not being based off scientific measures and other inadequacies. DSM-II: In 1968 the DSM-II was published following the publication of the ICD-8 but before the publication of its companion glossary. The DSM-II faced the same types of critiques over reliability and validity as the DSM-I and was culturally biased. DSM-III: In 1980 the DSM-III was published and included major changes. This edition used a multi-axial diagnostic system, which focused on five distinct areas of function (see The Five Axis of the DSM), had specific and explicit criteria for disorders, and was more a-theoretical than previous editions. At the same time the ICD-9 was published but failed miserably due to its lack of explicit, precise descriptions of disorders. The DSM-III was the first edition to become a widely accepted and used manual for mental diagnosis. Later a revised edition of the DSM-III, called the DSM-III-R, was published with more precise criteria and no reliance on the ICD-9, resulting in an even more widespread adoption of the book. DSM-IV: In 1994 the DSM-IV was published alongside the ICD-10, and was meant to be more compatible with the ICD-10 classification system. This edition was more heavily based in empirical research and included cultural, ethnic, age, and gender differences. DSM-IV-TR: In 2000 an updated version of the DSM-IV was published containing minor text revisions in the description of each disorder. This current edition is used by most mental health professionals as an assessment and diagnostic tool.


The Diagnostic and Statistical Manual of Mental Disorders, fourth edition text revision (DSM-IV-TR) is used by clinicians and psychiatrists to diagnose psychological illnesses. The DSM-IV-TR is published by the American Psychiatric Association and describes the majority of psychological disorders for both adults and children. The manual is a-theoretical and focuses mostly on describing symptoms as well as statistics concerning which gender is most affected by the illness, the typical age of onset, the effects of treatment, and common treatment approaches. The manual strives to assist clinicians to differentiate between disorders based upon discrete characteristics. The DSM-IV-TR is a multi-dimensional model containing five axes of assessment that are extremely critical to ensure an accurate diagnosis will be made.

The Five Axes of the DSM

The five axes of the DSM are labeled the primary clinical problem, personality disorders, general medical conditions, social and environmental stressors, and global assessment of overall functioning. Collectively, evaluation among all five axes attempt to give clinicians an overall idea of an individual to ensure a holistic treatment approach.

Axis I: Primary Clinical Problem

Axis I includes all mental health conditions except personality disorders and mental retardation. This is typically the initial complaint for which a client seeks medical attention. If the client does not have a mental health diagnosis that belongs on Axis I, V71.09 is placed in the diagnosis spot to show there is no diagnosis. A person can suffer from more than one disorder listed under Axis I and all are listed. This axis describes clinical symptoms that cause significant impairment. Disorders are grouped into different categories including adjustment disorders, anxiety disorders, childhood disorders, cognitive disorders, dissociative disorders, eating disorders, factitious disorders, impulse control disorders, mood disorders, psychotic disorders, sexual and gender identity disorders, sleep disorders, somatoform disorders, substance-related disorders,adjustment disorders, and pervasive developmental disorders.

Axis II: Personality Disorders

Axis II includes mental retardation and personality disorders. This axis describes long-term problems that are overlooked under Axis I. Many of these disorders, such as autism, are typically first evident in early childhood. These problems may not require immediate attention, but can complicate treatment and should be taken into account by the clinician. Mental retardation is characterized by intellectual impairment and deficits in other areas such as self-care and interpersonal skills. Axis II contains a rating scale for mental retardation. Personality disorders cause significant problems in how a patient relates to the world and specifically include paranoid personality disorder, schizoid personality disorder, schizotypal personality disorder, antisocial personality disorder, borderline personality disorder, histrionic personality disorder, narcissistic personality disorder, avoidant personality disorder, dependent personality disorder, and obsessive-compulsive personality disorder.

Axis III: General Medical Conditions

Axis III addresses any major medical conditions that may be relevant to the treatment of the mental health disorder. These include physical and medical conditions that may influence or worsen Axis I and Axis II disorders. Some examples may include HIV or AIDS, hypothyroidism, celiac disease a,nd brain injuries.

Axis IV: Social and Economic Stressors

Axis IV is used to report psychosocial and environmental factors affecting the person that can result from or contribute to Axis I, II, and III disorders. Some examples of these factors include: (1) problems with primary support group (divorce); (2) problems with social environment (death of a friend); (3) educational problems; (4) housing problems; (5) economic problems; (6) occupational difficulties; (7) legal difficulties; and (8) transportation difficulties. These are some categories a clinician will look at to see how the client is doing in life situations. Any social or environmental problems that may impact Axis I or Axis II disorders are accounted for in this assessment. These may include such things as unemployment, relocation, divorce, or the death of a loved one.

Axis V: Global Assessment of Overall Functioning

Axis V codes the "level of function" the individual has attained at the time of assessment, and, in some cases, is used to indicate the highest level of function in the past year. This rating helps the clinician understand how the above four axes are affecting the person, and what type of changes could be expected. This is coded on the Global Assessment of Functioning scale, which is a 0-100 scale, with 100 being "superior functioning in a wide range of activities", and 0 being "persistent danger of severely hurting self or others". It measures a patient's overall level of psychological, social, and occupational functioning on a hypothetical continuum.

Other Assessment Techniques


Due to the fact that diagnosing mental disorders is not as straightforward as other medical conditions such as diabetes, diagnostic procedures are also more complicated. Assessing an individual along the five axis of the DSM is often not adequate in achieving an accurate diagnosis. To ensure better diagnosis then, the LEAD model should be utilized. The LEAD model stands for Longitudinal, Expert, and making use of All available Data. Since symptoms can change over time it is important to use longitudinal assessments. Consulting an expert on any given disorder is also beneficial, and using all available data provides a more global assessment of the individual so that the most accurate diagnosis and treatment plan can be made.


There are three types of interviews that can be used in the diagnostic procedure. The first is called unstructured interviews in which the practitioner decides what questions to ask and when to ask them. The second is called semi-structured interviews and provides some guidance for questions but affords flexibility. The third is called structured interviews which uses standardized questions with no allowance for deviation. All types of interviews have relatively high validity when used appropriately, but they are often time consuming and prone to being influenced by subjectivity.

Brief Measures

Brief measures are typically used when delivering treatments and are often used in combination with interviews. These types of assessments allow for checking of progress in specific ares to help determine if a given treatment is effective.

Behavioral/Psychophysiological Assessments

Behavioral assessments include the use of self-monitoring data, such as a diary, and observational techniques. This type of assessment is not used often, but can more helpful in monitoring progress of individuals with ADHD, OCD, and phobias. Psychophysiological assessments are used to measure things like sleep disturbances and PTSD but can only be used in a lab and therefore have low reliability and validity and can not be generalized to real-world situations.

Global Measures

Global measures can be either projective or subjective measures. Projective techniques involve the use of ambiguous stimuli onto which a person "projects" their problems. An example of projective measures is the Rorschach Inkblot. Validity in projective measures is overall very low. Objective techniques are more structured and have specific questions with specific answers. While objective measures have moderate to low validity they are useful in differentiating between disorders with similar symptomology.


The DSM-V is scheduled to come out some time in 2012 with changes that will hopefully help clinicians to more accurately diagnose patients with a particular disorder. Some changes that may take place include having a severity scale in addition to the checklist model and having more research-supported criteria for mental illnesses

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