Factor Analysis and Preliminary Validation of the Mini-Mental State Examination from a Longitudinal Perspective

The Cognitive Abilities Screening Instrument (CASI) contains nine cognitive domains. Its total score has been used to screen for dementia in epidemiological studies conducted in the US, Japan and Taiwan, but its usefulness in distinguishing different levels of dementia has not been examined. This study was conducted to compare CASI scores of patients with Alzheimer’s disease (AD) with different levels of severity of dementia. The CASI was administered to 475 AD patients with mild, moderate or severe dementia according to the Clinical Dementia Rating Scale. The patients’ scores were compared to the scores of 475 age-, education- and gender-matched control subjects. More specifically, each patient’s score, X, was transformed to a z score with reference to the mean and SD of the scores of the control group, where z = (X – mean)/SD. Then, the mean of the z scores and the percentage of patients with z scores of <–2.0 were compared among the three patient groups. For the CASI total score and all of its nine domain scores, the mean z score decreased (except that for short-term memory) and a higher percentage of patients scored below the normal range with increasing severity of dementia. This study validates the usefulness of the CASI for assessing the severity of dementia. The domain scores differed in their relative usefulness for detecting dementia and for distinguishing in different levels of dementia.

Section: Discussionsupporting

confidence: 91%

Performance on the Cognitive Abilities Screening Instrument at Different Stages of Alzheimer’s Disease

Liu

Teng

Lin

et al. 2002

“…In choosing the 3-monih interval, \vc took into account the rate of cognitive decline occurring after I year in subjects with the diagnosis of proba ble dementia of Alzheimer type, namely an average o f 3.5 points on the MMSE [31], 12.3 points on the Cognition score drawn from the full-CAMDEX [32] and 2.6 points on the Blessed Information Mem ory Concentration Test [33], We assumed that at the 3-month follow up the variations in the scores due to natural cognitive decline would have been proportional to the elapsed time and thus quantitatively small (whereas after 12 months they should match the normative variations). If this small variability is confirmed by our study, we could argue that the short-and full-CAMDEX are psychometrically equivalent.…”

Section: Experimental Designmentioning

confidence: 99%

Validation of the Full and Short Forms of the CAMDEX Interview for Diagnosing Dementia

Neri

Roth

Mountjoy

et al. 1994

The present study compares the sensitivity and specificity of the short and full forms of the Cambridge Examination for Mental Disorders of the Elderly (CAMDEX) interview in diagnosing dementia. We tested 73 subjects meeting DSM-HIR criteria for dementia and 61 matched controls. The short version was applied 3 months after the full one to guarantee a relative stability of the tested functions. Referred to an independent clinical rating made at the beginning of the study, the levels of sensitivity and specificity were not significantly different in the two forms and fully comparable with those of the original full English version. Moreover, the scores on analogous sections of the two versions were highly correlated in the demented and control groups. These findings support the hypothesis that the short form of the CAMDEX maintains the psychometric properties of the full one, and consequently can be used in diagnostic routines for a variety of clinical and research purposes.

“…To determine the underlying structure of the severity measures, efforts have been made to factor analyze the performance by AD patients [25,[52][53][54][55], but these factors cannot be referred back to any independent standard. No study has yet solved the problem of clinically quantitating dementia by mapping symptom severity in living patients to a universal underlying parameter using a mathematical function.…”

Section: Introductionmentioning

confidence: 99%

Temporal Quantification of Alzheimer's Disease Severity: 'Time Index' Model

Ashford

Shan

Butler

et al. 1995

A fundamental issue in the clinical and neuropathological assessment of Alzheimer''s disease patients is quantification of dementia severity progression. Several methods have been advanced for the purpose of staging dementia with various sensitivities at different phases of the disease, but no mathematical function has been developed to link these measures to a physical continuum. Using a dynamic method for quantifying illness severity, change in severity over time was referenced to a cumulative temporal index, a physical dimension. Data from 33 patients with probable Alzheimer''s disease with at least 2 successive assessments on three 50-point scales measuring cognitive, behavioral, and daily living skills were used to determine rate of change. ''Fuzzy-logic'' smoothing of the data, integration over time, and least-squares regression were used to derive a cubic polynomial function to calculate a severity measure in which ''days of illness'' was estimated from the severity score. This method can be used to improve the comparability of performance across various mental status tests, and to link measures of very early phases of preclinical dementia and late profound dementia phases. This method also provides a description of an ''average'' time course for any population from which the index is derived.