Negative and positive affect as predictors of inflammation: Timing matters.
Very little research has assessed how measures of negative and positive affect (NA and PA) derived from assessments at multiple time points per day (e.g., via ecological momentary assessment [EMA]), as opposed to questionnaires that rely on recall over a longer period, are related to levels of peripheral inflammation. We examined how different indicators of NA and PA predicted concentrations of C-reactive protein (CRP) and seven peripheral inflammatory cytokines (IL-1β, IL-6, TNF-α, IL-8, IL-4, IL-10, and IFN-γ) that were examined in the form of an inflammatory composite. A community-based sample of 220 adults (62% Black/African-American and 25% Hispanic/Latino; aged 25-65; 65% female) completed questionnaires at baseline (including recalled affect "over the past month") and then provided EMA reports 5x/day for 14 days. Blood was drawn from each participant after completion of EMA and used to determine plasma levels of CRP and cytokines. Analyses examined if indicators of affect predicted inflammation, controlling for age, gender, body mass index, education, health conditions, and statin use. Neither recalled NA or PA nor momentary NA or PA (aggregated across the 14 days of EMA) were significantly associated with the cytokine composite or CRP. Negative mood more proximal to the blood draw (i.e., aggregated momentary NA in week 2 of EMA) was associated with the cytokine composite but not CRP. Exploratory moderation analyses revealed that the cytokine composite was also associated with PA in week 2 for men only, and with recalled NA for those with lower education. Exploratory analyses around temporal dynamics suggested that the timing of NA measurement relative to the blood draw mattered: Specifically, there were stronger trends of association between momentary NA and inflammatory cytokines when NA was assessed closer in time to blood collection. Future investigation of the relevance of temporal proximity and other measurement details may improve understanding of how affect relates to inflammation.