MENTAL STATUS EXAMINATION

Careful observation of the patient during the history may aid in evaluating her emotional status, memory, intelligence, powers of observation, character, and personality. Observe the general appearance, attitude, and behavior of the patient, including whether she looks tidy, neat, and clean or slovenly, dirty, and rumpled. Note the patient’s manner, speech, and posture, and look for abnormalities of facial expression. There may be odd or unusual dress, gait, and mannerisms; prominent tattoos; excessive jewelry; or other evidence of eccentricity. Unkempt, disheveled patients or those dressed in multiple layers may have dementia, frontal lobe dysfunction, a confusional state, or schizophrenia. Depression, alcoholism, and substance abuse may lead to evidence of self-neglect. Flamboyant dress may suggest mania or hysteria. Patients with visuospatial disturbances or dressing apraxia due to a nondominant parietal lesion may not be able to get into their clothes properly.

The patient may show interest in the interview, understand the situation, and be in touch with the surroundings, or she may appear anxious, distracted, confused, absorbed, preoccupied, or inattentive. The patient may be engaged, cooperative, helpful, and pleasant, or she may be indifferent, irritable, hostile, or belligerent. She may be alert, even hypervigilant, or dull, somnolent, or stuporous. Patients who are disinhibited, aggressive, or overly familiar may have frontal lobe lesions. Patients who are jumpy and hyperalert with autonomic hyperactivity (sweating, tachycardia) may be in drug withdrawal. Abnormal motor activity may include restlessness; repetitive, stereotypical movements; bizarre mannerisms; catatonia; and posturing. Inertia and psychomotor slowing suggest depression, dementia, or parkinsonism. Restlessness, agitation, and hyperactivity may occur with mania or drug ingestion. Note any tendency to emotional lability (pseudobulbar state) or apparent unconcern (la belle indifference). The ability to establish rapport with the patient may give insight into the personality of both the patient and the physician. It is sometimes informative to observe patients when they are not aware of being watched.

If there is any suggestion of abnormality from the interaction with the patient during the history-taking phase of the encounter, then a more formal MSE should be carried out. The formal MSE is a more structured process that expands on the information from the history. A detailed MSE should also be carried out if there is any complaint from the patient or family of memory difficulties, cognitive slippage, or a change in character, behavior, personality, or habits. For instance, formerly personable and affable patients who have become irascible and contentious may have early dementia. Other reasons to proceed further include symptoms that are vague and circumstantial, patients with known or suspected psychiatric disease or substance abuse, or when other aspects of the neurologic investigation indicate subtle or covert cognitive impairment could be present, such as anosmia, suggesting a frontal lobe tumor.

A number of short screening mental status evaluation instruments have been developed for use at the bedside and in the clinic. The most widely used of these is the Folstein mini–mental state exam (MMSE), but there are others (Box 8.1, Tables 8.3 and 8.4). The MMSE takes about 10 minutes to administer and has a series of scored questions that provides a localization-based overview of cognitive function, but it does not assess any function in detail. The maximum score is 30. Minimum normal performance depends on age and educational level, but it has been variously stated as between 24 and 27 (Table 8.5). A “one-minute” MSE comparing verbal fluency for semantic (category) naming compared with letter (phonemic) naming has been proposed to identify patients with probable AD.

The MMSE has limitations in both sensitivity and specificity, and it should not be used as more than a screening instrument for diagnosis. It is affected not only by age and education, but also by gender and cultural background. A cutoff score of 23 has a sensitivity of 86% and a specificity of 91% for detecting dementia in a community sample. But this score is insensitive and will not detect mild cognitive impairment (MCI), especially in well-educated or high-functioning patients (ceiling effect). A normal MMSE score does not reliably exclude dementia. There is also a relatively high false-positive rate. A 15-item extension, the modified MMSE, addresses some of the limitations of the traditional MMSE.

A comparison of the MMSE, Abbreviated Mental Test, and Short Portable Mental Status Questionnaire showed sensitivities of 80%, 77%, and 70% and specificities of 98%, 90%, and 89%, respectively. The Dementia Rating Scale, a 36-item measure of cognition with five subsets, takes longer to administer, but assesses more cognitive domains and is less likely to miss impairments. In patients in whom there is a question of cognitive impairment or a change in behavior and the MMSE or a similar instrument is normal, formal neuropsychological testing may provide more detail regarding the mental status. Formal neuropsychological testing may be useful in other situations as well (Box 8.2). The MMSE score in normal adults is reasonably stable over time; in patients with AD, it declines at an average rate of three points per year.

Before making judgments about the patient’s mental status, especially memory, the examiner should ensure that the patient is alert, cooperative, attentive, and has no language impairment. Mental status cannot be adequately evaluated in a patient who is not alert or is aphasic. Evaluation of patients with altered consciousness is discussed in Chapter 51. To avoid upsetting the patient, it is desirable, when possible, to examine the mental functions unobtrusively by asking questions that gently probe memory, intelligence, and other important functions without obvious inquisition.

ORIENTATION AND ATTENTION

The formal MSE usually begins with an assessment of orientation. Normally, patients are said to be “oriented times three” if they know who they are, their location, and the date. Some examiners assess insight or the awareness of the situation as a fourth dimension of orientation. The details of orientation are sometimes telling. The patient may know the day of the week but not the year. Orientation can be explored further when necessary by increasing or decreasing the difficulty level of the questions. Patients may know the season of the year if not the exact month; conversely, they may be oriented well enough to know their exact location down to the street address, hospital floor, and room number. Most patients can estimate the time within one-half hour. Orientation questions can be used as a memory test for patients who are disoriented. If the patient is disoriented as to time and place, she may be told the day, the month, the year, the city, etc., and be implored to try to remember the information. Failure to remember this information by a patient who is attentive and has registered it suggests a severe memory deficit. Occasionally, patients cannot remember very basic information, such as the year, the city, or the name of the hospital, despite being repeatedly told, for more than a few seconds. In the presence of disease, orientation to time is impaired first, then orientation to place; only rarely is there disorientation to person.

Poor performance on complex tests of higher intellectual function cannot be attributed to cortical dysfunction if the patient is not attentive to the tasks. Defective attention taints all subsequent testing. Patients may appear grossly alert but are actually inattentive, distractable, and unable to concentrate. An early manifestation of toxic or metabolic encephalopathy is often a lack of attention and concentration in an apparently alert patient, which may progress to delirium or to a confused state. Confusion, inattention, and poor concentration may also be seen with frontal lobe dysfunction, posterior nondominant hemisphere lesions, and increased intracranial pressure. Lesions causing apathy or abulia also impair attention. Patients with dementing illnesses are not typically inattentive until the cognitive deficits are severe. The possibility of a central nervous system toxic or metabolic disturbance should be considered when the patient is inattentive.

Having the patient signal whenever the letter A is heard from a string of random letters dictated by the examiner, or having the patient cross out all of the A’s on a written sheet may reveal a lack of attention or task impersistence. In the line cancellation test, the patient is requested to bisect several lines randomly placed on a page. Inattentive, distractible patients may fail to complete the task. Patients with hemineglect may bisect all of the lines off center, or they may ignore the lines on one side of the page.

Digit span forward is a good test of attention, concentration, and immediate memory. The examiner gives the patient a series of numbers of increasing length, beginning with 3 or 4, at a rate of about one per second; the patient is asked to repeat them. The numbers should be random, not following any identifiable pattern, for example, a phone number. Backward digit span, having the patient repeat a series of numbers in reverse order, is a more complex mental process that involves working memory; it requires the ability to retain and manipulate the string of numbers. Expected performance is 7 ± 2 forward and 5 ± 1 backward. Reverse digit span should not be more than two digits less than the forward span. Forward digit span is also a test of repetition and may be impaired in aphasic patients. Another test of attention and concentration is a three-step task. For instance, tear a piece of paper in half, then tear half of it in half, then tear one half in half again, so that there are three different sizes. Give the patient an instruction such as, “Give the large piece of paper to me, put the small piece on the bed, and keep the other piece.” Another multistep task might be, “Stand up, face the door, and hold out your arms.”

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