This chapter discusses scales and inventories for mental status assessment. Scales are instruments for measuring or grading mental status attributes, and inventories are questionnaires for surveying or cataloging mental status traits. Scales and inventories are useful for screening for the presence of cognitive impairment and not for making a diagnosis. Screening is a method for determining whether there is a potential problem that could indicate a disorder. Mental status scales and inventories are indicated for identifying those patients who need more detailed and comprehensive assessment, whether an extended neurobehavioral status examination (NBSE) or referral for neuropsychological testing. In addition, they quantify or semiquantify the cognitive impairment, indicate degree of severity, allow for communication with others, and facilitate follow-up over time. This chapter on mental status scales and inventories discusses their general aspects, indications and the choice of instrument, psychometric properties, application for longitudinal assessment, and interpretation and limitations.
General Aspects
Mental status scales are brief, structured instruments with specific administration and scoring, and mental status inventories gather information by a list of questions. Some scales are combinations of mental status testing and inventories, for example, the Blessed Dementia Scale and the Alzheimer Disease Rating Scale. Mental status scales and inventories are either general instruments for cognitive deficits, or they are targeted instruments aimed at specific cognitive abilities, syndromes, or diseases. Inventories, as opposed to scales, tend to be targeted at behavioral disturbances. The purpose of general mental status scales is to distinguish patients with impaired versus normal cognition. General scales are sensitive for identifying screening for patients with the most common cognitive impairments, but they are not for diagnosing diseases or for brain-behavior localization. No mental status scale covers all areas of cognition; therefore they cannot be entirely comprehensive screens for all possible cognitive impairments. There are over 50 mental status scales in wide use. There is no single scale that is the “gold standard”, most have sufficient accuracy (sensitivity tempered by specificity) for dementia screening and share a number of advantages and deficiencies ( Tables 15.1 and 15.2 ).
| Administration, relatively easy with minimal instruction |
| Brevity, < 5–30 minutes |
| Cutoff screening identify impaired for further evaluation |
| Item heterogeneity, individual items may be sensitive to different disorders when individually inspected |
| Interclinician communication, facilitated |
| Longitudinal follow-up when using same instrument over time |
| Mental status screening of populations for prevalence of neurocognitive disorders |
| Normative data sometimes available |
| Quantitation of severity |
| Reliable, test-retest |
| Results, immediately available (vs. delayed report) |
| Targeted scales available |
| Valuable as a brief MSX when items include different cognitive domains |
| Ceiling effects or floor effects |
| Cognitive impairment not comprehensive |
| Content and comprehensiveness, variable |
| Heterogeneity of items affects validity |
| Interindividual variability |
| Item order or item difficulty, variable |
| Items per cognitive domain vary greatly |
| Language complexity effect (in some cases) |
| Specificity, absent for specific diseases or brain-behavior localization |
| State effects, i.e., distraction, fatigue, cooperation, etc. |
| Validation effects, not as applicable for different demographic groups |
| Versions for telephone or videoconferencing may not be available |
General mental status scales vary in their coverage of cognitive areas. Most scales have items for memory and orientation, as these are affected early in Alzheimer disease and other dementias. This is followed by items for mental control/attention, language, visuospatial skills, and calculations. Few extend to examination of executive abilities, semantics, praxis, or socioemotional changes. This is evident in the content of the Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA), two of the most widely used scales in the clinical setting and used as illustrative examples in this chapter (also see Chapter 16 ). The MMSE items include 10 for orientation, 3 for registration, 3 for memory, 8 for language, 5 for mental control/attention, and 1 for visuospatial skills. In contrast, the MoCA items include 6 for orientation, 5 for memory, 6 for language, 6 for mental control/attention, 3 for visuospatial, and 4 for executive abilities (including clock hands) (author’s evaluation). Even within these content areas, there are differences in what is tested. For example, for language the MMSE, but not the MoCA, includes auditory comprehension, reading, and writing, whereas the MoCA, but not the MMSE includes verbal fluency. Of course, more than one cognitive domain may affect an individual item, but this comparison clearly shows the content variability that extends across mental status scales. Moreover, the number of items per cognitive domain, as well as the length of the instrument, can vary greatly.
The examiner should consider a number of other differences evident on both mental status scales and inventories. Although all aim for brevity, the administration times may vary between 5 minutes or less to 15–30 minutes or more. Scales may be constructed with relatively harder or easier items overall. For example, the MMSE is much easier than the MoCA, despite a suggested average adjustment for age and education. The order of presentation of items or inventory questions can make a difference in patient responses, for example, whether easy items are presented first, when patients are less fatigued, or presented last, when they distracted when items are less challenging. Orientation items are presented first in the MMSE and last in the MoCA. Memory performance on a scale may vary with the number of intervening items between registration and delayed recall. There is one intervening item on the MMSE, and there are six on the MoCA. On the MMSE, it is conceivable to still have the registration words in working memory when asked for them on delayed recall. Finally, mental status scales differ in their sensitivity to the effects of age, education, and sociocultural and language background, and there is little adjustment for these variables on these scales. Indeed, even slight differences in the complexity of the language used by scales and inventories may affect performance.
Indications and Choice of Instrument
Examiners screening for cognitive impairment usually prefer brief instruments that can be easily and quickly administered and interpreted in the context of a clinical neurological or psychiatric examination. The choice of rating scale or inventory can vary with the specific goals of the evaluation. For example, if the goal is to administer the mental status scale over the telephone or by videoconference, the examiner needs to know what modifications to the scale, if any, may be required from the in-person administration. The choice of instrument may also depend on what is being used in the clinician’s setting or institution, and whether it is in the public domain and freely accessible.
Although aimed at detecting cognitive impairment in general, most scales focus on the detection of dementia in the elderly as a surrogate for all cognitive decline (see Box 15.1 ). In screening for dementia, clinicians can administer general mental status scales in clinical encounters or at the bedside as part of the regular clinic visit or inpatient assessments. Clinicians use mental status scales to augment screening for early signs of dementia in the elderly as part of the Medicare Annual Wellness Visit, but they are not universally recommended unless the patient is symptomatic or there are concerns from patients and families. If dementia is suspected in an individual patient, the examiner needs to proceed to more extensive testing with the NBSE or referral for neuropsychological assessment. In sum, mental status scales are useful and practical for screening for potential cognitive decline in a clinical setting, but not comparable to the NBSE or neuropsychological testing, which can more thoroughly establish the diagnosis. In addition, among patients who already have established dementia, these scales can provide information about dementia severity but not about the specific cause.
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