Abnormal neuropsychological memory testing and hippocampal volume in a clinical population. (P5.1-013)

Objective: Identifying the proportion of individuals with abnormal neuropsychological memory testing scores based on quantified hippocampal volumes. Background: Determining the likelihood of abnormal memory test scores based on hippocampal volumes can aid the diagnostic process for dementia when neuropsychological testing is not available. Design/Methods: 177 patients who received hippocampal volumetric MRI readings were provisionally diagnosed after a neurologic and neuropsychological evaluation with probable Alzheimer’s disease (AD n=65), Amnestic Mild Cognitive Impairment (MCI n=64), or subjective cognitive complaints (SCC n=48). Results: Hippocampal volumetric measurements significantly correlated with the neuropsychological memory tests. 48% of those with AD and 45% of those with MCI had hippocampal volumes below the 5th percentile (versus 4% of those with SCC). Hippocampal volumes below the 16th percentile were seen in 62% of the AD group, 58% for MCI and 8% in SCC. ROC calculation of area under the curve was .80 for hippocampal volume and 1 memory test falling below 1.5 standard deviations and .74 for two memory tests being impaired at that level. Sensitivity for those with a 5% or less volumetric reading was 95% while specificity was 56% for one impaired memory test and 81% and 52% for having two impaired memory tests. Sensitivity and specificity declined for those with 16% or less volumetric measurements to 88%/44% for one impaired test and 74%/36% for two impaired memory tests. Conclusions: Volumetric measurements of 5% or below were quite sensitive to the likelihood of having one impaired neuropsychological memory test although both sensitivity and specificity declined once the hippocampal readings moved closer to the lower end of the normal range. Thus while hippocampal volume loss is related to having an abnormal memory test finding, extreme values are necessary for confidence in the likelihood of a clinical memory disorder. Disclosure: Dr. Ruchinskas has nothing to disclose. Dr. Nguyen has nothing to disclose.