Abstract
The current study examined whether personality domains have nonmonotonic relationships with functional outcomes, specifically in relation to quality of life and impairment. Four samples were utilized, which were drawn from the United States and Germany. Personality trait domains were measured via the IPIP-NEO and PID-5; quality of life (QoL) was measured with the WHOQOL-BREF, and impairment was measured using the WHODAS-2.0. The PID-5 was analyzed in all four samples. Two-line testing, which fits two spline regression lines separated at a break point, was conducted to evaluate potential nonmonotonicity of the relationship between personality traits and quality of life. Overall, results demonstrated little support for nonmonotonic relationships in the PID-5 and IPIP-NEO dimensions. Rather, our results indicate that there is one clear pathological pole of major domains of personality that is associated with lower quality of life and increased impairment. (PsycInfo Database Record (c) 2023 APA, all rights reserved).