Intracellular cytokine production and cognition in healthy older adults

Elevated concentrations of the pro-inflammatory cytokines IL-1β and IL-6 have been associated with impaired cognitive performance. There are, however, few studies that have examined the relationship between cytokine production and specific aspects of cognition in healthy older individuals. Two-colour flow cytometry was used to determine intracellular cytokine production by activated monocytes, and neuropsychological tests were performed using the Cambridge Neuropsychological Test Automated Battery (CANTAB) in 93 apparently healthy men and women aged 55-70 years. A series of hierarchical regression analyses was carried out to examine the contribution of IL-1β and IL-6 (% expression and production (antibody binding capacity (ABC))) to recognition, attention and working memory, after controlling for socio-demographic variables (age, sex and social class). IL-1β% expression and IL-6 production predicted aspects of working memory. Recognition memory was found to be sensitive to the affects of age and social class. The current study suggests that higher intracellular cytokine production by activated monocytes may be predictive of lower cognitive performance in working memory in healthy older individuals. These findings indicate that utilization of models for in vivo cytokine production upon immune challenge may be useful in studying specific aspects of memory affected during inflammatory responses, for example in individuals at risk for cognitive decline owing to age-related inflammatory disorders.