Heartbeat scaling in early adolescents: Its association with anxiety symptoms and sensitivity to punishment

Background/Objective: Anxiety symptoms in adolescence have been found to be associated with heart rate variability (HRV) linear features, but more basic properties of the cardiac system remain unexplored. This study focused on the fractal nature of 90 minute-long interbeat fluctuations from 24 adolescents with high anxiety and 26 with low anxiety to (a) evaluate if allometric scaling exponents and linear HRV measures allow for distinction between groups, and (b) assess the associations between these measures and sensitivity to punishment (SP), a temperamental characteristic strongly correlated with anxiety. Method: Cardiac functioning was recorded and allometric exponents and vagally mediated HRV as indexed by the high frequency (HF) band power were calculated. Results: While the exponents from the high anxiety group were significantly higher than those from low anxiety participants (p < .05), just marginal differences were found for the HF measure (p = .057). Furthermore, exponents were positively correlated with SP scores and several anxiety scale scores, but no more correlations were found. Conclusions: These results show that beyond parasympathetic functioning, basic properties of the cardiac system may be altered in young, anxious adolescents. These properties, therefore, can provide useful information for assessing adolescents at risk of anxiety disorders.