A new rating instrument, the Alzheimer's Disease Assessment Scale, was designed specifically to evaluate the severity of cognitive and noncognitive behavioral dysfunctions characteristic of persons with Alzheimer's disease. Item descriptions, administration procedures, and scoring are outlined. Twenty-seven subjects with Alzheimer's disease and 28 normal elderly subjects were rated on 40 items. Twenty-one items with significant intraclass correlation coefficients for interrater reliability (range, .650-.989) and significant Spearman rank-order correlation coefficients for test-retest reliability (range, .514-1) constitute the final scale. Subjects with Alzheimer's disease had significantly more cognitive and noncognitive dysfunction than the normal elderly subjects.

Fourteen case histories of persons who had a histological diagnosis of either senile dementia of the Alzheimer type, multiinfarct dementia, or a mixed dementia composed of these two types and who showed evidence of a moderate to severe dementia on psychological testing were rated for the presence of thirteen clinical features comprising Hachinski's Ischemic Score. These features are frequently considered primarily characteristic of vascular dementia. Persons with senile dementia of the Alzheimer type were clearly differentiable from persons with multiinfarct dementia and mixed dementia, while the latter two groups were indistinguishable from one another. In our sample, eight features were found to characterize those persons with vascular dementia. These data verify the usefulness of the Ischemic Score in differentiating between senile dementia of the Alzheimer type and vascular dementia.

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Our objectives were to investigate the utility of the Hachinski Ischemic Score (HIS) in differentiating patients with pathologically verified Alzheimer's disease (AD), multi-infarct dementia (MID), and "mixed" (AD plus cerebrovascular disease) dementia, and to identify the specific items of the HIS that best discriminate those dementia subtypes. Investigators from six sites participated in a meta-analysis by contributing original clinical data, HIS, and pathologic diagnoses on 312 patients with dementia (AD, 191; MID, 80; and mixed, 41). Sensitivity and specificity of the HIS were calculated based on varied cutoffs using receiver-operator characteristic curves. Logistic regression analyses were performed to compare each pair of diagnostic groups to obtain the odds ratio (OR) for each HIS item. The mean HIS (+/- SD) was 5.4 +/- 4.5 and differed significantly among the groups (AD, 3.1 +/- 2.5; MID, 10.5 +/- 4.1; mixed, 7.7 +/- 4.3). Receiver-operator characteristic curves showed that the best cutoff was < or = 4 for AD and > or = 7 for MID, as originally proposed, with a sensitivity of 89.0% and a specificity of 89.3%. For the comparison of MID versus mixed the sensitivity was 93.1% and the specificity was 17.2%, whereas for AD versus mixed the sensitivity was 83.8% and the specificity was 29.4%. HIS items distinguishing MID from AD were stepwise deterioration (OR, 6.06), fluctuating course (OR, 7.60), hypertension (OR, 4.30), history of stroke (OR, 4.30), and focal neurologic symptoms (OR, 4.40). Only stepwise deterioration (OR, 3.97) and emotional incontinence (OR, 3.39) distinguished MID from mixed, and only fluctuating course (OR, 0.20) and history of stroke (OR, 0.08) distinguished AD from mixed. Our findings suggest that the HIS performed well in the differentiation between AD and MID, the purpose for which it was originally designed, but that the clinical diagnosis of mixed dementia remains difficult. Further prospective studies of the HIS should include additional clinical and neuroimaging variables to permit objective refinement of the scale and improve its ability to identify patients with mixed dementia.