Background: The ε4 allele of the apolipoprotein E (APOE) gene and low levels of cerebrospinal fluid (CSF) amyloid β-proteins 42 (Aβ) have previously been associated with increased risk of cognitive decline in old age. In this study we examine the interaction of these markers with episodic memory in a sample identified as having mild cognitive impairment (MCI).
Methods: The sample (N = 149) was drawn from the Gothenburg MCI study and measured according to three free recall tests on three occasions spanning over four years. Second-order Latent Curve Models (LCM) were fitted to the data.
Results: Analyses accounting for age, gender, education, APOE, Aβ42, and interaction between APOE and Aβ42 revealed that the ε4 allele was significantly associated with level of memory performance in the presence of low Aβ42 values (≤452 ng/L). Associations between memory performance and Aβ42 were significant among the ε4 carriers but not among the non-carriers. The Aβ42 marker was, however, significantly associated with changes in memory over the study time period in the total sample.
Conclusion: The findings support the hypothesis of an interactive effect of APOE and Aβ42 for memory decline in MCI patients.