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Both amnestic and nonamnestic deficits have been observed in patients with mild cognitive impairment (MCI). Most studies have focused on impairment on single cognitive tests rather than amalgamation of the results of several measures to arrive at a composite impairment index. In this investigation, we examined 20 MCI patients diagnosed as prodromal Alzheimer's disease, AD (mean Mini-Mental State Examination, MMSE = 26.1; SD = 1.7) and determined the extent to which they could be differentiated from 70 normal elderly controls based on composite measures at 1.5-SD and 2.0-SD cutoffs for impairment. At the 1.5-SD cutoff, the median number of memory indices impaired in the MCI-AD group was 5 of 7, whereas at the 2.0-SD cutoff, the median number was 4 of 7. A median of 3 of 7 and 2 of 7 nonmemory indices were impaired at 1.5- and 2.0-SD cutoffs for impairment. Receiver operator characteristics (ROC) analyses indicated that the total number of memory tests impaired at 2.0 SD (sensitivity = 95.0%/specificity = 84.3%) and the composite measure of both impaired memory and nonmemory measures (sensitivity of 85.0%/specificity of 100%) had high levels of discrimination and may have utility as indices of early impairment as well as severity of MCI.

Objective: Although mild cognitive impairment (MCI) is characterized by performance on memory and other measures below expected normative values, neither a scientific rationale nor a consensus exists regarding which measures have the most use or the optimal cutoffs to use to establish impairment., Methods: Different memory measures were administered to 80 normal community-dwelling subjects divided into two age groups. This provided conormed data on eight different memory indices by which to compare 23 nondemented clinically diagnosed patients with MCI who met all other criteria for Alzheimer disease (AD)., Results: On immediate memory for passages, delayed visual reproduction, object memory, and a measure sensitive to semantic interference, 70%-78% of patients with MCI were identified as impaired at 1.5 standard deviations or greater below expected levels. Conditional logistical regression for age-matched samples indicated that consideration of raw scores for these neuropsychologic tests in combination did not significantly change the odds of MCI diagnosis. When impairment relative to the total normal elderly sample was calculated based on one or more impairments at a 1.5 or greater cutoff, specificity fell below acceptable levels when more than three memory measures were considered., Conclusion: An array of widely used neuropsychologic measures demonstrated utility in distinguishing patients with MCI-AD from cognitively normal community-dwelling elders. The appropriateness of more or less stringent cutoffs was highly influenced by the number of measures considered. These findings have important implications regarding the choice of cut points for impairment used for the diagnosis of MCI in both research and clinical settings.