Individual differences in the perception of optimism and disease severity: a study among individuals with Parkinson's disease.

The extent to which individuals with Parkinson's disease (PD) show lability in optimism was explored in the present study. The relationship between optimism and perceived disease severity was examined as well. Twelve individuals diagnosed with PD completed self-report measures for 70 consecutive days. All individuals in this study showed lability in optimism over short time periods; however, 67% of the sample showed no pervasive negative changes in optimism over time. Increased levels of optimism on one day were predictive of decreased perceived disease severity the next day for one-fourth of the sample, after controlling for negative affect. Individual differences in the relationship between optimism and disease severity provided support for the idea that living with chronic illness has no monolithic meaning. More optimistic individuals reported less need for assistance with basic functional abilities than less optimistic individuals. The usefulness of lability in optimism among individuals with PD is discussed.