Cytokines and Memory Across the Mature Life Span of Women

Increasing evidence suggests a role of the immune system in modulation of cognition, but details on affected memory systems are largely lacking. We therefore aimed to study the relation between selected cytokines and subsets of memory, and the impact of age in these relations. From a random population-based sample (the Betula Prospective Cohort Study), 298 women (age 45-90) were studied in terms of episodic recall and recognition, semantic fluency and knowledge, and prospective memory. Circulating cytokines of relevance for cognition and aging were measured with ELISA. Levels of interleukin (IL)-6 and sIL-2R were significantly and negatively associated with most cognitive variables, while the opposite was true for IL-1β. Age shared substantial variance with both cytokines and memory, and turned most correlations non-significant when controlled for together with education, BMI and presence of disease. Interactions between age and cytokines were further analyzed in multiple regressions. For IL-6, significant negative interactions with age were found for semantic fluency (p<0.05) and prospective memory (p<0.01), and for sIL-2R in predicting semantic knowledge (p<0.05), indicating an increased negative impact of these cytokines on memory with increasing age. In conclusion, the study indicates a relation between cytokines and memory that appears to be largely mediated by age, and supports the suggestion that cytokine dysregulation with higher age may interact with cognitive aging.