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Psychiatry - Diagnosis & Classification

This page explains what is meant by a psychiatric diagnosis, methods for making diag-noses, and aspects of diagnostic reliability, validity, and utility. Psychiatric and somatic comorbidities are elucidated. It includes a section on the influence of traditional medicine for most of the world’s population. It provides an overview of diagnostic interviews and screening questionnaires.

Psychiatry - Classification & Disorders

Structured diagnostic interviews and screening questionnaires:

Many structured diagnostic interviews have been tested over the years. The first was the Present State Examination (PSE) in Great Britain in the 1950s that was integrated into the Schedules for Clinical Assessment in Neuropsychiatry (SCAN, see below). The Mental Status Examination was developed in the United States in the 1960s.

Diagnostic interviews differ in scope and the qualifications of the interviewer, and in being based on ICD or DSM classification. Some are comprehensive and designed to find all psychiatric morbidity in general population samples, in primary care, or in tertiary care. Others deal primarily with e.g., affective disorders, substance use disorders, or personality disorders. Web-based case finding questionnaires are being developed to encourage people to seek treatment, as most individuals with conditions (such as substance use disorders, anxiety disorders, depression) amenable to treatment are not receiving any kind of treatment. Self-rating symptom scales are available for case-finding in e.g., the reception area of an outpatient unit, or to assess symptom changes in treatment studies.

Below are short descriptions of some currently used instruments.

The MINI Neuropsychiatric Interview was developed by David Sheehan and Yves Lecrubier as an efficient tool for the experienced mental health worker to look for 15 psychiatric diagnoses in an interview that takes about 30 minutes: Affective, anxiety, psychotic, substance use, eating, and antisocial personality disorders as well as current suicidality. The subject is instructed to simply answer yes or no to each question. Each section has one or a few lead-in questions, and in-depth questions in case there is a positive response. It is essential that the subject understands the questions, so the interviewer may have to repeat them or explain them. The questions are purposely overinclusive (false positives) so that cases will not be missed. It is critical that the interviewer has clinical judgment to assess the value of the subject’s responses. Since somatic diseases may have caused the symptoms (such as a brain tumor, thyroid disease, or adverse effects of medications and substances), a physician must validate the interview results. An experienced nurse or psychologist or mental health worker may do the actual interview. The MINI is the most common interview in drug treatment studies, and is available in over 40 languages. The English MINI version 6.0 was updated in 2009. It can be down-loaded without charge from

The Composite International Diagnostic Interview 3.0 (CIDI) is a fully structured non-clinical interview intended for use in general population surveys

The CIDI-SAM (SAM is for Substance Abuse Module) is a structured interview that ascertains DSM-III, DSM-III-R, Feighner, RDC and ICD-10 diagnoses for alcohol, tobacco and nine classes of psychoactive drugs. It was designed at the request of the World Health Organization to expand the substance abuse sections of the CIDI. The SAM module takes an average of 45 minutes to complete.

The Schedules for Clinical Assessments in Neuropsychiatry (SCAN) is a semi-structured clinical interview to assess major mental disorders in clinical settings.

Schedules for Affective Disorders and Schizophrenia (SADS) has been produced in several versions since 1975, and can take up to 3 hours to complete by a trained clinician. It is the basis for the Structured Clinical Interview for Diagnosis (SCID I and SCID II) that is also an expert instrument.

The Personality Diagnostic Questionnaire (PDQ-4) holds 99 true/false items to screen for 11 DSM-IV personality disorders

The General Health Questionnaire (GHQ-12) was developed in the 1970s for self-screening in primary care, public health surveys, and other settings with lower degrees of psycho-pathology. GHQ-12 asks if 12 symptoms have been present in recent weeks much more than usual, rather more than usual, no more than usual or not at all. Total scores derived using the Likert method (3-2-1-0) range from 36 to zero with higher scores denoting greater morbidity. It has proved reliable, stable and valid when tested in numerous primary care and hospital settings with a sensitivity and specificity versus CIDI of 79% and 77% respectively at cutpoint 11/12.

Another self-screen questionnaire is the Hospital Anxiety Depression Scale (HADS), developed in the UK to find cases with symptoms of anxiety and depression. It consists of 14 items that a subject can respond to within a few minutes, for example prior to a physician visit.

The Clinical Interview Schedule (CIS) was developed to assess anxiety, depression and somatization. The revised version (CIS-R) has been used in population surveys by lay interviewers.

The Kessler Psychological Distress Scale (K-10) checks if 10 mental symptoms have been present in the last 4 weeks for all, most, some, a little or none of the time. It was designed for use in general health surveys and has proved reliable and valid in surveys in the United States and in Australia mentalhealth/K10_English%5B1%5D.pdf.

Legal issues and psychiatric diagnoses

The courts in most societies take a diagnosis of a psychiatric disorder into account before passing sentence. Usually the court will order that a subject undergoes a forensic psychiatric examination to determine whether there is a severe psychiatric disorder, and whether the subject can be held accountable for his actions. Does a subject with schizophrenia or antisocial personality disorder understand the consequences of his actions for other people and for society? Did the mother kill her child because of a depression, or because she was under the influence of auditory hallucinations? If there is an indisputable organic brain disease is the subject to be held accountable for a crime? These are evaluations that require an experienced, professional, thorough and highly regulated psychiatric assessment. The law varies between nations, and the court may order commitment to psychiatric care, or a prison term or both.

In many societies doctors are responsible by law to report if a patient is deemed unfit to possess a fire arm, or unfit to have a driver’s license, or to have custody of a child. Such reports require a careful psychiatric diagnosis.

Medical records

In most countries, the history and mental health status examination should result in a clinical evaluation of the patient and at least one psychiatric diagnosis, all of which make up the core of the patient’s medical record (chart). This may be a preliminary or definite diagnosis. For example, a patient presenting with typical symptoms of schizophrenia can be given a preliminary diagnosis that is confirmed after 6 months, because of the duration criterion in DSM-IV.

The physician can be held accountable to a disciplinary board if the diagnostic procedure is not properly recorded. The diagnosis is the basis for justifying treatments and perhaps involuntary care.

Records are still written by hand or typed in many countries. Increasingly in Europe and in the United States there is a move to electronic medical records. This is in the interest of administrators and regulators to hold physicians accountable and to increase patient safety. Insurers have a stake in psychiatric diagnoses to assess the risk of a potential subject for a health insurance or retirement plan. If records contain valid and reliable information about the patient’s diagnosis, treatments, suicidal risk, and risk for aggression it will increase the quality of care. If all of the patient’s health care contacts (the emergency room, primary care unit, psychiatric clinic) are eligible to read the patient’s record it will increase patient safety, and reduce unnecessary investigatory procedures. There are opportunities for longitudinal case studies, research, and allocation of health care resources.

The potential drawback with a unifying electronic medical record is that it will be at the expense of person integrity and privacy. Particularly, a psychiatric record will contain highly sensitive information that should not be accessible to insurers and employers. Patients should have the option to decline such a unifying medical record that can otherwise be read by all eligible users of a computerized record system.


Anne Farmer, Peter McGuffin, Julie Williams. Measuring Psychopathology. Oxford Univer-sity Press 2002.
Samuel B. Guze. Why Psychiatry is a Branch of Medicine. Oxford University Press, 1992.
Mario Incayawar, Ronald Wintrob, Lise Bouchard, Goffredo Bartocci (eds.). Psychiatrists and Traditional Healers. Unwitting Partners in Global Mental Health. Wiley-Blackwell, 2009.
Donald W. Goodwin, Samuel B. Guze. Psychiatric Diagnosis - 4th Edition. Oxford University Press, 1989.

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