Abstract
Impulsivity represents an individual's tendency to act on urges without sufficient forethought. Heightened impulsivity is a hallmark of many mental health disorders. Objective impulsivity assessments could improve risk evaluation, diagnosis, and behavioral outcome monitoring in impulsivity-related health disorders. Towards objective impulsivity assessment, in this work, we identify impulsivity correlates in objective measurements, investigate their complementarity, and contrast impulsivity mechanisms across health conditions. We analyzed behavioral tests, heart rate variability (HRV), and fMRI-based brain connectivity in 227 healthy participants and 34 participants with mood disorders. Impulsivity dimensions had complementary correlates in objective measurements, with fMRI providing the strongest correlates. Multimodal assessment provided high r-squared (adjusted) values in modeling impulsivity of the mood disorder participants (e.g., r-squared of 0.73, p < 0.001 for attentional impulsivity) but low r-squared for healthy participants (the best r-squared being 0.17, p < 0.001 for sensation seeking impulsivity). The differing association between impulsivity dimensions across the two populations likely indicates a health condition-specific impulsivity mechanism across populations. The complementary nature of objective impulsivity correlates across populations demonstrates the distributed signature of multidimensional impulsivity, likely capturing the complexity of behavioral modeling.