A letter in Psychiatric News discusses the problems with the mental status examination:
The MSE, often characterized as psychiatry's equivalent of the physical exam, is in fact a mixture of historical information, observations, and conclusions. "Thought process" is known from examination, but what we describe as "thought content" is history—phobias, compulsive behavior, and suicide ideation, for example. Hallucinations occurring at the time of the examination are "current mental state"; yesterday's hallucinations are history. "Judgment" is an evaluation.
The MSE is flawed because of a lack of agreement about the meaning of some of the terms. "Mood" and "affect" are often confounded. "Orientation to person" refers to the patient's awareness of his or her own identity, but some take it to mean recognition of the examiner, while "orientation to situation" is not a standard question. "Judgment" may reflect the patient's answers to test questions, or it may reflect recent conduct, such as fighting with a police officer or giving money to a con man. Some describe a patient as having impaired judgment if he or she has a drug habit or stops taking prescribed medication.
Note to medical students: the mental status examination is an examination of the patient's complete mental state, including mood, organization of thoughts, abnormal perceptions (hallucinations), cognition, etc. This is different from the Folstein Mini-mental status exam, which is a 30 point scale that measures only cognition.