Mediational factors underlying cognitive changes and laterality in affective illness.

Affective illness has been associated with lateralized right hemisphere deficits and global cognitive dysfunction. However, there has been very little exploration of information-processing strategies that may underlie cognitive changes in this population. Twenty euthymic, drug-free, bipolar patients and 20 controls were given a series of tasks to assess lateralized impairment of the cerebral hemispheres and sequential (analytic) versus simultaneous (gestalt) information-processing strategies. There were no differences between patients and controls in tests sensitive to right or left hemisphere impairment or in total errors on a face recognition task. However, patients tended to rely on individual facial features for recognition whereas controls were able to synthesize multiple elements of the faces. Moreover, on a task that required holistic synthesis of multiple stimulus elements (Street Gestalt Completion Test), patients made significantly more errors than controls. Implications for information-processing changes in bipolar affective illness are discussed.