Markers of Alzheimer's disease in a population attending a memory clinic

Background: New marker-based criteria for the diagnosis of Alzheimer's disease (AD) were recently proposed. We describe their operational translation in 144 consecutive patients referred to our Memory Clinic. Methods: Visual ratings of hippocampal atrophy and of cortical glucose hypometabolism in magnetic resonance imaging and positron emission tomography, and concentrations of total tau and A beta 1-42 in cerebrospinal fluid were assessed in 12 patients with subjective memory complaints (SMCs) (Mini-Mental State Examination [MMSE] score, 28.0 +/- 1.1 [mean SD]), 37 with mild cognitive impairment (MCI) (MMSE, 25.1 +/- 3.6),55 with AD (MMSE, 21.1 +/- 3.5), and 40 with non-AD dementia (MMSE, 21.6 +/- 5.5). Results: The sensitivity for AD of each individual biomarker was higher (65% to 87%) than for MCI (18% to 50%). Each biomarker's specificity for SMC and non-AD dementias was good to moderate (83% and 53%). Positivity for at least one marker increased the probability 38 times of belonging to the AD group (P < 0.0001). Conclusion: The new diagnostic criteria can be operationalized in clinical routines, but longitudinal studies of MCI patients will need to assess the criteria's prognostic value. (C) 2009 The Alzheimer's Association. All rights reserved.