Dimensional Approaches to Cognitive Function in Psychopathology and Aging

Abstract

Traditional methods in the study of psychopathology have largely focused on reified disorders that fail to reflect biologically valid psychiatric pathophysiology. This nosological approach defines separate disorders as distinct entities despite significant symptom and trait overlap across diagnostic categories. Moreover, these transdiagnostic symptoms and traits are commonly associated with specific sources of cognitive dysfunction that also transverse diagnostic labels. An alternative approach to nosology is to use dimensions that represent individuals as points along the full range of a characteristic or cognitive process. The dimensional approach allows us to examine how changes in a particular cognitive function are associated with psychiatric illness, or the aging process. In the current dissertation, we leverage the advantages of computational modeling and dimensional approaches to the study of psychology. We examine dimensions of cognitive function and transdiagnostic psychiatric dimensions. Study 1 examines goal-directed decision-making across the psychopathology spectrum. We show that incentives can be used to boost a computational signature of goal-directed planning despite increasing severity of transdiagnostic symptoms and traits. Study 2 does a transdiagnostic examination of the law of least mental effort which states we tend to minimize mental effort or work. We show that elevations in some transdiagnostic symptoms and traits are associated with deviations from this general principle. In study 3, we return to the use of incentives to ask if we can boost goal- directed planning in older adults. Our results suggest that older adults naïve to behavioral paradigms are impaired in their ability to increase a computational signature of goal-directed planning. The results across these three studies suggest that dimensional approaches provide a flexible, and widely applicable, method to study a broad range of psychological phenomena.