Incremental Validity of Self- and Informant Report of Personality Disorders in Later Life.

Research shows moderate agreement between different sources of information when assessing personality disorders (PDs) in older adults. The differences between measurement methods appear to be not only the result of measurement error, but also an indication that each source holds nonredundant information relevant to PD diagnosis. The current article examines three sources of diagnostic information (self-report, informant report, and clinical interview) and the utility of these instruments in predicting important outcomes in older adulthood. We analyzed data from 1,630 adults between the ages of 55 and 64 years participating in a longitudinal study of later life. PD symptomatology was assessed using multiple methods, which were then used to predict health, marital satisfaction, and cognitive decline. All three sources contributed significantly to the prediction of these outcomes, with important implications for the assessment of older adults in research and clinical settings.