The primary diagnostic modality in psychiatry is the clinical interview, which includes a mental status examination. Because physical illness frequently exists concurrent with mental illness, laboratory screening tests, radiographic studies, EEG's and a physical examination with special emphasis on the neurologic exam, provide further data which can be essential to the accurate and complete diagnostic evaluation of psychiatric conditions. Modern psychiatric diagnostic nomenclature is obtained from the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV). This manual offers a cookbook approach to psychiatric diagnoses by listing specific diagnostic criteria for each diagnosis, and allows professionals to speak the same language when using diagnostic labels. Psychological tests, such as the Minnesota Multiphasic Personality Inventory (MMPI), may aid in diagnosis, however, are not generally available or used by the GMO.

As with any medical evaluation, the first part of the psychiatric evaluation is the gathering of a complete history. Because psychiatric conditions often impair the patient's ability to accurately recount his or her own signs and symptoms, observations by others that know the patient are often invaluable in accurately making a psychiatric diagnosis. The psychiatric history should include age, sex, race, marital status, rate, branch of service, length of service, command, and source of referral, and whether or not there is a history of previous psychiatric diagnoses.

Mental Status Exam

The second part of the clinical interview is the mental status examination, which is a systematic documentation of the quality of mental functioning of the patient at the time of the interview. It not only aids in the current diagnosis and formulation of a treatment plan, but can later serve as an important baseline for future reference, since psychiatric conditions often vary over time, and accurate diagnosis is often retrospective. The mental status examination can be divided into following general areas:

• Appearance and Behavior.
  Grooming, mannerisms, psychomotor activity, abnormal movements, body language, attitude toward the examiner, state of consciousness - whether alert, hyper alert, or lethargic.

• Speech
  Loudness, speed, spontaneity, interruptability, vocabulary, and articulation.

• Mood and Affect
  Mood is the subjective description of a sustained emotional state (i.e. what the patient says – "I feel depressed"). The affect is the patient's current emotional state as it is observed by the interviewer. Is the observed affect congruent with the expressed mood?

• Thought-form and Content
  Are the patient's thought processes logical and coherent? Is there evidence of circumstantiality, flight of ideas, loosening of associations, or perseveration?

• Assessment of Thought Content
  Check for abnormal preoccupations and obsessions, excessive suspiciousness, delusions, compulsive rituals, phobias, hallucinations, and whether or not there is suicidal or homicidal ideation. (A more complete assessment of suicidal potential is contained elsewhere in this manual.)

• Cognition
  Attention, concentration, orientation, abstraction, memory, including remote, recent, and immediate recall, intellectual functioning, including fund of knowledge and calculations (much of this information will already be apparent from other portions of the interview). A useful screening test for cognitive impairment is the Mini-Mental Status Examination, which provides a brief standardized screening which is particularly useful in cases of suspected organic impairment. The Mini-Mental Status Exam can be especially helpful when it is repeated to assess change in a patient over time.

• Insight and Judgment
  Does the patient recognize his or her signs and symptoms, and the way in which they may have impaired his or her judgment?

As can be seen by reviewing the DSM-IV, diagnosis of many psychiatric conditions requires the exclusion of underlying physical conditions that may account for the patient's symptomatology. Physical illnesses are quite common among psychiatric patients, and can be causative or exacerbating factors in psychiatric symptoms. There is no consensus as to the routine screening tests that should be performed in patients presenting with psychiatric symptoms. However, most recommendations include the following lab tests:

• Complete blood count

• Serum chemistry panel

• Thyroid function tests

• Screenings for HIV and syphilis

• Urinalysis

• Depending on the presenting symptoms, a drug screen, blood alcohol level, B12, and folate levels can also be useful.

An ECG is often important because of the potential cardiac effects of many psychotropic medications. When presenting psychiatric symptoms include alteration of consciousness without apparent cause, or significant impairment of cognition that is acute in nature, EEG's and radiographic studies such as CT or MRI scans of the head may be indicated. Although many of these tests could be performed in the absence of physical symptoms, a careful physical and neurological evaluation can often direct and prioritize the organic work-up.

This reference provides useful tools that aid in the formulation of a differential diagnosis for presenting psychiatric symptoms, and helps improve reliability of psychiatric diagnosis. It uses a multiaxial classification system in which Axis I contains the diagnoses based on the clinical syndrome of signs and symptoms, Axis II contains the diagnosis of personality or developmental disorders, and Axis III documents physical disorders. At times, patients may have overlapping symptoms that can lead to more than one psychiatric diagnosis. DSM-IV usually includes exclusionary criteria, which prevent unnecessary or invalid duplicate diagnoses.

Documentation cannot be overemphasized especially when performing a psychiatric evaluation. The previously mentioned diagnostic modalities will primarily serve to aid in answering the following questions:

• Is the patient suicidal, homicidal, or psychotic?

• Does the patient have any underlying medical conditions that are presenting with psychiatric symptoms?

• What general diagnostic categories does the patient's symptoms represent?

• Does the condition warrant MEDEVAC or transfer?

References

1. Tomb, David A: Psychiatry for the House Officer, 3rd Edition, Williams and Wilkins, Baltimore, MD, 1988.

2. American Psychiatric Association : Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition Revised, (DSM-IV), Washington, DC, American Psychiatric Association, 1994.

3. The American Psychiatric Press: Textbook of Psychiatry, Talbot, Hale, and Udofsky, editors; American Psychiatric Press, Inc., Washington, DC, 1988.