USING Logistic Regression to Identify Factors Associated with Practice Effect of Repeated Mis Scores in Preadvise

The primary aim of the NIA-sponsored PREADVISE trial is to determine the effectiveness of vitamin E and selenium in preventing the onset of Alzheimer's disease (AD) in over 6,667 men in collaboration with the NCI-sponsored SELECT prostate cancer prevention study. PREADVISE participants have annual Memory Impairment Screen (MIS) evaluations.

The mean age of the 86.2% white repeat cohort at baseline was 67.6 years with 15.0 years of education. MIS scores ranged from 3 to 8 with 67.9% scoring a perfect 8, and 80.0% of these participants scoring 8 at the second assessment.

Of the 1,650 enrollees scoring less than 8 at baseline, 30.3% had greater scores on the second MIS. A logistic regression showed that having 16+ years of education, age at enrollment, taking Statins medications, and presence of CABG were associated with improvement in MIS performance.

Of the 4,626 men scoring 7 or 8 at baseline, 4.8% showed a decline to a score below 7 at the second screen (increased risk for MCI or dementia). In a logistic model, white race, 16+ years of education, age at baseline, and at least some college, presence of diabetes were associated with a decline.

In conclusion, college education has a positive effect, whereas age, CABG, and Statins have a negative effect, on the odds that a practice effect is observed among those who scored less than 8 on the baseline MIS. In addition, the data suggest that white race, high education, younger age, and absence of diabetes protect against a decline.