Information processing and cognitive organization in unipolar depression: specificity and comorbidity issues

This study investigated information processing and cognitive organization in clinical depression. The specificity of various cognitive mechanisms to depression was also examined. Twenty-six depressed/anxious individuals, 24 pure depressives, 25 never-depressed anxious controls, and 25 nonpsychiatric controls completed a modified Stroop task, the Self-Referent Encoding Task, and two tasks designed to assess cognitive structure. Comorbid depressed/anxious, depressed, and anxious groups performed similarly to one another but differed significantly from nonpsychiatric controls, on the processing and organization of negative content. Specificity to depression was also obtained, as both depressed groups endorsed and recalled less positive information and organized positive self-relevant information with less interconnectedness than anxious individuals and nonpsychiatric controls. These results suggest that depressed individuals have an interconnected negative self-representational system and lack a well-organized positive template of self. These findings are discussed in terms of cognitive models of depression and the tripartite model of depression and anxiety.