Predicting Alzheimer's disease with practice effects, APOE genotype and brain metabolism

After the paper Cognition or genetics. Predicting progression to Alzheimer's disease with practice effects, APOE genotype and brain metabolism [Neurobiol Aging, 2018; 71:234-240] was published, we identified a coding error of one of the variables analyzed. To correct, update and expand the previous work, we compared simple and complex regression-based Reliable Change Index (RCI_RB) to analyze the risk of progression to AD (AD-risk) after six years using either delayed recall or recognition scores. Auditory Verbal Learning Test scores at six months for 394 individuals with normal cognition from the ADNI were used to build the regression. In 816 individuals with amnestic mild cognitive impairments, the AD-risk was associated with age, brain metabolism, APOE-ε4, recognition hits, the discrimination index, and low practice effects in the complex RCI_RB only. The complex RCI_RB outperformed the simple RCI_RB. Small correlations were found between practice effects and both Aβ (highest r = 0.218) and TAU (highest r = -0.183). RCI_RB are computationally simple and provide sensitive AD-risk estimates in combination with APOE-ε4 and FDG-PET.