A comparison of the Addenbrooke's Cognitive Examination (ACE), conventional neuropsychological assessment, and simple MRI-based medial temporal lobe evaluation in the early diagnosis of Alzheimer's disease

Abstract

Objective: To examine the contribution of the Addenbrooke's Cognitive Examination (ACE), neuropsychological assessment, and a magnetic resonance imaging (MRI)-based temporal lobe rating scale to the prediction of which patients with questionable dementia will progress to Alzheimer's disease (AD).

Methods: Fifty subjects (19 early AD, 31 questionable dementia [QD]) underwent the ACE, a neuropsychological evaluation, and a volumetric MRI. The degree of atrophy of hippocampal, parahippocampal, and other temporal lobe structures was assessed using a validated visual rating scale. Subjects were followed 8 monthly for an average of 19.1 months.

Results: Of the 31 QD subjects, 11 converted to AD within 24 months of follow-up (another 2 developed dementia with Lewy bodies) and 18 were nonconverters. Converters were impaired relative to nonconverters at baseline on measures of episodic and semantic memory (category fluency and naming) and the ACE. Converters also had a greater degree of hippocampal and parahippocampal atrophy. Discriminant analysis demonstrated that the best single test for distinguishing converters was the ACE. In combination, the hippocampal rating and category fluency were also contributory.

Conclusions: Progression to AD in patients with QD is best predicted by neuropsychological measures, particularly those that assess episodic and semantic memory, although simple rating methods based on MRI may have an adjunctive role.