Interpreting Addenbrooke's Cognitive Examination-III Scores in Dementia: Performance Distributions and Clinically Meaningful Change

Abstract

Background: The Addenbrooke's Cognitive Examination-III (ACE-III) is a common cognitive screening measure. We provide performance deciles, descriptive performance bands and indices of reliable change between repeat assessments using the ACE-III in a large cohort of dementia participants and healthy controls.

Methods: Baseline data from 727 participants diagnosed with a dementia syndrome and 157 healthy controls were used to calculate performance deciles and descriptive bands. A subset of 393 participants diagnosed with a dementia syndrome completed two annual assessments. These data were used to calculate 95% confidence intervals of characteristic yearly change in each dementia syndrome. Data from a subset of 74 healthy participants who completed two assessments were used to calculate reliable change indices.

Results: Baseline performance was grouped into five descriptive performance bands across the entire spectrum of scores: Very Mild, Mild, Moderate, Severe and Very Severe. Deciles and performance bands are provided for all dementia participants combined, for each syndrome where n > 50, and for healthy controls, stratified by group, sex and years of education. A decline of -7 to -9 points yearly was characteristic for the dementia population, and this varied between syndromes. Reliable change calculations indicate that a 5-point decline from within the 'normal' range (88-100) is the minimum clinically important decline on the ACE-III.

Conclusions: This study presents a suite of reference data on the ACE-III in a range of dementia syndromes, providing important insight and support to clinicians who work with people living with cognitive impairments.

Keywords: Alzheimer's disease; cognitive screening; frontotemporal dementia; neurodegeneration; primary progressive aphasia.

FIGURE 1

ACE‐III first visit (T1) performance distribution for all dementia syndromes (combined). Derived T1 performance bands are overlaid. The X‐axis represents ACE‐III total score, and the Y‐axis represents the proportion of the sample that obtained that score. Demographic data for these participants is described in Table 1 (‘dementia [combined]’).