P1‐030: Biomarkers of depressive symptoms in Alzheimer's disease: Gender differences

Abstract

Late-life depression has been associated with increased levels of a variety of pro-inflammatory cytokines. Current research on biomarkers in late-life depression has identified a number of potential biomarkers: IL-6, IL-10, IL-1, CRP, TNF-α ± and MIF. BDNF has been found to significantly impact expression of depression in mild AD patients. Other biomarkers, such as ICAM-1, have been associated with depressive symptoms in vascular models of late-life depression. The present study investigated the relationship between serum based biomarkers linked to late-life depression and depressive symptoms.91 individuals enrolled in the TARCC cohort diagnosed with probable Alzheimer's disease (Age = 78.32, SD = 7.922) and 161 cognitively intact elderly controls (Age = 69.10, SD = 8.625) were evaluated. Serum biomarkers from the panel of depression biomarkers were analyzed. Depression severity was derived from the GDS 30 total score and four symptom clusters. Logistic regression was applied to determine the nature of the relationship for each group with gender, age and education co-varied. Data were stratified by gender with age and education co-varied. ANOVA revealed no significant difference between case and controls on any of the biomarkers. Regression for all participants revealed significant but weak relationships (R 2 = ≤.030) for MIF as a significant predictor (P = .05) of total score and 3 of the 4 symptom clusters and CRP predicting scores on Apathy. Regression analyses by case status and gender revealed that MIF was a strong predictor of Depression in Alzheimer's males accounting for 12% of the variance in total GDS score and 15% to 51% of the variance in 3 of the symptom clusters with TNF ± accounting for 12% of the variance in Apathy score. For Alzheimer's females MIF, ICAM and CRP accounted for 26% of the variance in Apathy and CRP and TNF ± accounted for 20% of the variance in Cognitive Impairment with no other significant relationships. Lower levels of MIF are significantly related to depressive symptoms especially for males in Alzheimer's disease independent of affect of MIF levels on cognition. Cognitive status and gender are important determinants of the relationship of pro-inflammatory biomarkers to depression.