Psychologists and psychiatrists use interviews, testing and sometimes brain scans to determine if someone is suffering from a mental illness. Usually if patients ask for help with a particular symptom or problem, they will be cooperative and the diagnosis of psychological disorders is relatively smooth. In other cases, the psychologist will have to be somewhat of a detective, sorting through the information obtained in an evaluation. Although most assessment methods are fairly effective. failure to take a person’s culture into account or relying solely on an interview may lead to a misdiagnosis.
Initially, the psychologist will obtain a patient history and ask questions about the patient's concerns. It’s important for the clinician to obtain a thorough medical history as well as a psychological one, and to know what medications the patient is taking. The psychologist will listen carefully for patterns in the patient’s answers and the feelings and thoughts described that may point to a diagnosis of psychological disorders.
The patient’s appearance and behavior will also be closely observed. A distressed person who appears unkempt with poor hygiene or odd attire might be unable to care for himself. Schizophrenia and other psychotic disorders often cause sufferers to present a flat affect, or dulled-down demeanor, and thought and speech patterns that aren’t usually found in healthy people. Substance abuse is a separate problem that can also cause these symptoms, and requires very specific treatment. A patient who is unable to express what is bothering him may be a candidate for further medical and psychological testing.
The Diagnostic and Statistical Manual of Mental Disorders (DSM), a frequently updated reference book, is typically consulted to sort out symptoms that may point to a certain disorder. Tests such as the Minnesota Multiphasic Personality Inventory (MMPI), the Thematic Apperception Test (TAT) and the classic Rorschach inkblot test evaluate more subtle traits of personality and psychopathology. Once diagnosis of psychological disorders has been reached, the psychologist can begin or recommend a course of treatment, usually involving therapy and sometimes medication.
Interviews alone are not reliable indicators in the diagnosis of psychological disorders. There have been cases of defendants in criminal cases who were able to convincingly fake illness through initial assessments, until a more thorough analysis ferreted out their attempts. A narrow focus on biology and biochemistry may cause clinicians to misinterpret symptoms that have a cultural or religious element or cause. Certain genetic disorders are also more prevalent in people with a particular heritage.