Evaluation of a performance-rating method to assess awareness of cognitive functioning in Huntington's disease

Objective: Anosognosia, or lack of awareness of symptoms, is commonly observed in Huntington's disease (HD) using patient/informant-report discrepancy methods. The purpose of this study was to examine the utility of a performance-rating method for assessing awareness of cognitive performance in HD. Method: Persons with manifest HD (n = 54) rated their performance on the daily living tests from the Neuropsychological Assessment Battery (NAB) using a bell curve. We also examined patient/informant-report discrepancies of executive functioning (FrSBe) in a subset (n = 47) of patients and their informants. Results: Patients were able to reliably use our method of categorizing their performance as evidenced by significant correlations between verbal descriptions of their performance and the percentile ratings they indicated on the bell curve. Patients across the range of observed Unified HD Rating Scale motor scale scores rated their performance on the NAB tasks significantly higher than actual performance for both pretest prediction and posttest evaluation ratings. Only patients with more severe motor impairment underestimated their problems relative to informant report on the FrSBe. Conclusions: This is the first study to use a performance-rating method for examining awareness in HD. Patients could reliably use this performance-based bell curve method to provide accurate estimations of their performance and as a group they tended to overestimate performance as has been demonstrated in previous studies. Unlike previous studies using self-report methodology, we also demonstrated decreased awareness in the persons with HD with less severe motor impairment using the performance-rating method, suggesting the two methods may measure different constructs of awareness.