2 Predictors of Memory Deficits in Patients with Subjective Cognitive Decline, Mild Cognitive Impairment, and Alzheimer’s Disease - Do Disease Severity Moderate the Association?

Abstract

Objective:Age, sex, education, memory, and the APOE e4 allele are related to Alzheimer’s disease (AD) risk. Recently it was suggested that low body mass index (BMI) contributes to the development of AD. The objective of this study was to examine how delayed recall of a word list was influenced by demographic variables, APOE and BMI in people with memory problems, and to investigate whether the impact of these variables was smaller at higher disease severity levels.Participants and Methods:The participants were 1206 patients in the Norwegian NorCog registry diagnosed with either subjective cognitive decline (SCD) (n=274), mild cognitive impairment (MCI) (n=444), or AD (n=488). ANOVAs and hierarchical regression were applied to examine whether the delayed recall part of the 10-word test of the CERAD-WL was associated with age, sex, education, APOE (e4/non-e4) and BMI. Analyses were run separately for SCD, MCI and AD patients.Results:There were significant bivariate differences (p<.001) between the three patient groups for all variables; the AD patients were older, less educated, more were women, more had APOE e4 alleles, and they had lower BMI. For the SCD group, 34% of the total variance (R2) of the dependent variable was explained. All independent variables except BMI (p=.07) had a significant contribution in the prediction. For MCI, 18% of the total were explained. All variables except education and sex showed significant contribution to R2. For the AD group, R2 was 13%. Sex and BMI did not contribute significantly.Conclusions:As expected, the performance on CERAD-WML was influenced by age, education and sex in the SCD group, whereas the associations between memory function and the three demographic variables were less clear among patients with MCI and AD. ApoE genotype influenced on the CERAD-WML results among all patients, whereas BMI only influenced on the results among patients with SCD and MCI. Our findings do not support that BMI is associated with delayed recall of memory in AD.