Implicit Affect, Heart Rate Variability, and the Metabolic Syndrome

OBJECTIVE: Greater negative affect has been associated with an increased risk of the metabolic syndrome (METs). However, all studies to date have examined this association using explicit affect measures based on subjective ratings of emotional experiences. Prior studies suggest that implicit affect, representing the automatic, prereflective appraisal process involved in conscious emotional experiences, is associated with physiological stress responses independent of explicit affect. Furthermore, low resting heart rate variability (HRV) may increase the risk of stress-related diseases. The goals of this study were to evaluate the associations between implicit and explicit affect and METs and to assess whether these associations were amplified by lower HRV. METHODS: This secondary analysis of a larger study included 217 middle-aged women who completed measures of implicit affect, explicit affect, high-frequency HRV, and the different components of METs. RESULTS: There was a significant interaction between implicit negative affect and HRV predicting METs (odds ratio = 0.57, 95% confidence interval = 0.35-0.92), such that the combination of higher implicit affect and lower HRV was associated with a greater likelihood of METs. Similarly, there was a main effect of implicit negative affect as well as an interaction between implicit negative affect and HRV on the lipid accumulation product (b (standard error) = -0.06 (0.02), 95% confidence interval = -0.11 to -0.02), a combination of waist circumference and triglycerides. CONCLUSIONS: Higher implicit negative affect in the context of lower HRV may be related to a greater risk of METs. The present findings highlight the relevance of including implicit affect measures in psychosomatic medicine research.