Risk for bipolar spectrum disorders associated with positive urgency and orbitofrontal cortical grey matter volume

• DOI: 10.1016/j.nicl.2022.103225
• Publication Date: 2022-10-12T09:08:31Z
• Authors: Ann L. Carroll; Katherine S.F. Damme; Lauren B. Alloy; Corinne P. Bart; Tommy H. Ng; Madison K. Titone; Jason Chein; Anna C. Cichocki; Casey C. Armstrong; Robin Nusslock
• Keywords: Adult; Orbitofrontal cortex (OFC); Bipolar Disorder; Adolescent; Bipolar spectrum disorder (BSD); Computer applications to medicine. Medical informatics; R858-859.7; Prefrontal Cortex; Regular Article; Grey matter volume; Magnetic Resonance Imaging; Young Adult; 03 medical and health sciences; 0302 clinical medicine; Reward; Impulsive Behavior; Humans; Neurology. Diseases of the nervous system; Gray Matter; RC346-429; Positive urgency

Bipolar spectrum disorders (BSDs) are associated with reward hypersensitivity, impulsivity, and structural abnormalities within the brain's reward system. Using a behavioral high-risk study design based on reward sensitivity, this paper had two primary objectives: 1) investigate whether elevated positive urgency, the tendency to act rashly when experiencing extreme positive affect, is a risk for or correlate of BSDs, and 2) examine the nature of the relationship between positive urgency and grey matter volume in fronto-striatal reward regions, among individuals at differential risk for BSD. Young adults (ages 18-28) screened to be moderately reward sensitive (MReward; N = 42), highly reward sensitive (HReward; N = 48), or highly reward sensitive with a lifetime BSD (HReward + BSD; N = 32) completed a structural MRI scan and the positive urgency subscale of the UPPS-P scale. Positive urgency scores varied with BSD risk (MReward < HReward < HReward + BSD; ps≤0.05), and positive urgency interacted with BSD risk group in predicting lateral OFC volume (p <.001). Specifically, the MReward group showed a negative relationship between positive urgency and lateral OFC volume. By contrast, there was no relationship between positive urgency and lateral OFC grey matter volume among the HReward and HReward + BSD groups. The results suggest that heightened trait positive urgency is a pre-existing vulnerability for BSD that worsens with illness onset, and there is a distinct relationship between positive urgency and lateral OFC volume among individuals at high versus low risk for BSD. These findings have implications for understanding the expression and development of impulsivity in BSDs.