Research shows a gap between perceived cognitive dysfunction and objective neuropsychological performance in persons with chronic diseases. We explored this relationship in persons with rheumatoid arthritis (RA).
Individuals from a longitudinal cohort study of RA participated in a study visit that included physical, psychosocial, cognitive, and biologic metrics. Subjective cognitive dysfunction was assessed using the Perceived Deficits Questionnaire (PDQ; range 0-20, where higher scores = greater perceived impairment). Objective cognitive impairment was assessed using a battery of 12 standardized neuropsychological measures yielding 16 indices. On each test, subjects were classified as impaired if they performed 1 SD below the age-based population norms. Total cognitive function scores were calculated by summing the transformed scores (range 0-16, where higher scores = greater impairment). Multiple linear regression analyses determined the relationship of the total cognitive function score with the PDQ score, controlling for sex, race, marital status, income, education, disease duration, disease severity, depression, and fatigue.
One hundred twenty subjects (mean ± SD age 58.5 ± 11.0 years) were included. Mean ± SD scores of total cognitive function and the PDQ were 2.5 ± 2.2 (range 0-10) and 5.8 ± 3.8 (range 0-16), respectively. In multivariate analysis, there was no significant relationship between the total cognitive function score and the PDQ score. However, depression and fatigue (β = 0.32, P < 0.001 and β = 0.31, P = 0.001, respectively) were significantly associated with the PDQ score.
The findings emphasize the gap between subjective and objective measures of cognitive impairment and the importance of considering psychological factors within the context of cognitive symptoms in clinical settings.