Multiple Perspectives on the Impact of Cognitive Control Processes on Disorganization in Psychosis

Abstract

Disorganization, a psychosis symptom factor denoting abnormal speech and behavior, is thought to reflect impaired cognitive processing. However, despite their theoretical similarities, there appears to be little consistent evidence of a distinctive relationship between disorganization and cognitive control. This dissertation examined the relationship between disorganization and two key cognitive control mechanisms, context processing and prepotent response inhibition, also known as proactive control and reactive control. Chapter 2 compared the functional neuroanatomy of cognitive control in schizophrenia patients and healthy controls. Both context processing and prepotent response inhibition marshaled activity in prefrontal, anterior cingulate, posterior parietal, and middle temporal structures. Controls demonstrated greater prefrontal activity during context processing than did patients. However, BOLD signal did not predict disorganization severity. Due to potential bias in symptom ratings, Chapter 3 controlled for ethnic minority identity while examining the relationship between disorganization and cognitive control in a psychosis sample. Disorganization predicted variance in context processing and prepotent response inhibition, unlike other symptoms. However, the context processing model also found ethnic minority identity predictive, particularly if identifying as Black. Chapter 4 explored the potential influence of visual processing within a new cognitive control task. Behavioral metrics were uncorrelated with either self-report or experimenter-rated disorganization. However, context processing trended with general cognitive impairment in psychosis patients. Visual processing was associated with context processing and prepotent response inhibition in controls, while only the Middle Frontal Gyrus activated in patients. Generalized smooth models suggest visual processing regions may predict cognitive impairment better than traditional regions of interest. Implications and future directions are considered.