Classification of Mental Disorders

Diagnosis is the identification or recognition of a disorder on the basis of its characteristics. Making a diagnosis enables the clinician to refer to the base of knowledge that has accumulated with regard to the disorder. However, assigning a diagnosis does not mean that the etiology is known.

Classifying disorders is accomplished through categories (qualities) and dimensions (how much of a characteristic that person exhibits). A classification system helps clinicians match their client’s problems with the form of intervention that is most effective.

There are two main diagnostic systems: the Diagnostic Statistical Manual (DSM) and the International Classification of Diseases (ICD). The DSM is used mainly in the United States. The ICD is dominant in Europe. The most recent edition of the DSM is the DSM-IV-TR. The DSM is an evolving document produced by the American Psychiatric Association. The DSM-V is due to appear in 2012. A group of 28 experts decide what goes in and out depending on relevant research.

There are 200 specific diagnostic categories and 18 primary headings. It lists specific criteria for each diagnostic category. It employs multiaxial classification: 5 axes.



The manual encourages clinicians to consider the influence of cultural factors in both expression and recognition of symptoms of mental disorders. The DSM-IV-TR includes a glossary of culture bound syndromes.

How should a classification system be graded?

Generally the best way to grade a classification system is based on its reliability and validity. Reliability is a measurement of consistency such as diagnoses. Inter rater reliability is the rate of agreement among raters. It wouldn’t be good to have two clinicians with the same patient arriving at two very different diagnoses. If you identify the wrong problem, you will be working towards the wrong solution (most of the time). Validity deals with the meaning or importance of a measurement. There various forms of validity: etiological validity, concurrent validity, and predictive validity.

Are there any issues with the DSM?

The boundary between normal and abnormal behavior is not always clear cut. Clinicians must rely on their own subjective judgment. Despite all of their training, everyone is prone to make mistakes. Cutoff points required for a diagnosis and specific time periods used in the definition of various disorder are other issues that the DSM needs to address. One issue that isn’t the DSM’s fault is that its widespread acceptance may hinder the consideration of promising alternative classification systems. It doesn’t necessarily classify clinical problems into syndromes in the simplest and most beneficial way. A lot of diagnoses tend to overlap leading to comorbidity.

Clinical Assessments

Clinical assessments are important for many reasons. A clinical assessment is the process of collecting and interpreting information that will be used to understand another person. The assessor must adopt a theoretical perspective regarding the nature of the disorder. An assessment is used for making predictions, planning treatments, and evaluating treatments. When conducting assessments, psychologists must be concerned about the consistency of behavior across time and situations. Generally, psychologists seek out more than one source of information when conducting an assessment.

For the most part, interviews are the preferred method of making an assessment.  It provides an opportunity to obtain people’s own description of their problems. The clinician is able to observe important features of a person’s appearance and nonverbal behavior during the interview. They are generally structured: a question-answer format with a specific list of detailed questions. Like anything in life, there are advantages and disadvantages to structured interviews.

Another way of making an assessment is the observational method. It may be formal or informal. Observations are often conducted in the natural environment. Although sometimes it is conducted in controlled situations: (observation rooms). The observer uses rating scales to make judgments that place the person (observee) somewhere along a dimension. The final results provide abstract descriptions of a person’s behavior.

Some observational assessments rely on behavioral coding systems. A behavioral coding system focuses on the frequency of specific behavioral events. It requires extensive time and training in order to use. It is used more frequently in research

Some assessments are self-report inventories. Most of these are aimed at measuring a client’s personality. MMPI-2 is one such test that asks straightforward questions, has validity scales, and  is scored based on an explicit set of rules derived from empirical research.

Another type of personality test is one where the client is presented an ambiguous stimuli and asked to describe what he or she sees in the picture. The Rorschach Test and the Thematic Apperception Test (TAT) are two examples.

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