P2‐150: Predicting conversion to Alzheimer's disease in Mild Cognitive Impairment: cued recall versus free delayed recall

Identification of early Alzheimer's disease (AD) has become very important as new treatments are being developed. Episodic memory tasks appear to have predictive power for indicating early AD as episodic memory function is anatomically located within medial temporal lobe structures, including the hippocampus, which is meanwhile the location with highest densities of AD neuropathological lesions. Most studies that have addressed the issue of neuropsychological prediction of conversion to AD in MCI patients, have emphasised the diagnostic value of free delayed recall deficits. This prospective, longitudinal study aims at investigating whether cued recall tasks are also able to predict conversion to AD amongst MCI patients. At baseline the cognitive part of the Cambridge Examination for Mental Disorders of the Elderly, a Dutch variation of Rey's Auditory Verbal Learning Test (free delayed recall), the Memory Impairment Screen plus (MISplus; verbal cued recall) and the Visual Association Test (VAT; visual cued recall) were administered to 40 patients diagnosed with MCI. Both after 18 months and after 48 months, MCI-patients were reassessed and a follow up diagnosis was established. Of those who were seen for follow up after 18 months (n = 31), 7 fulfilled (NINCDS-ADRDA) criteria of probable AD, while 24 did not convert. Of those who were then seen after 48 months (n = 28), 15 converted to AD, while 13 did not convert. The forward binary logistic regression analyses, with free delayed recall, MISplus and VAT as possible predictors, showed that only the MISplus remained in the analyses, indicating that this test contributed most to the prediction of conversion, both after 18 months (Wald X2(1) = 5.78, p = .016 (O.R. = 0.28, CI95%:0.099-0.790) and after 48 months (Wald X2(1) = 8.06, p = .005 (O.R. = 0.36, CI95%:0.181-0.731). With the MISplus, a predictive accuracy of 87% (after 18 months) and 86% (after 48 months) was obtained. Verbal cued recall is a better predictor of conversion to Alzheimer's disease in Mild Cognitive Impairment than free delayed recall and visual cued recall.