Interpreter-Mediated Neuropsychological Testing of Spanish-speakers with limited English Proficiency: Effects on Test Scores

Nearly 13.8 million Hispanics in the United States speak English “less than very well.” This has important implications for the field of clinical neuropsychology. Patients who do not speak English fluently are being increasingly referred for neuropsychological services, and many of these individuals are assessed with the aid of interpreters. However, whether or how the use of an interpreter has an effect on neuropsychological test scores is not known. The effect of an interpreter, in fact, could be substantial, making this issue all the more deserving of rigorous investigation. The primary objective of the current study was to determine whether using an interpreter to conduct neuropsychological testing of Spanish speakers with limited English proficiency (LEP) had an effect on the neuropsychological test scores. Participants included 40 neurologically normal Spanish-speakers with LEP, ages 18-65 years, (M= 39.65, SD =13.91) who completed a 2-hour battery of verbal and nonverbal neuropsychological tests both with and without an interpreter. The condition of test administration was counterbalanced across participants and test score differences between the two conditions were compared. Results indicated that use of an interpreter significantly affected mean scores for some neuropsychological tests from the verbal modality. Also, variability in test scores generally was higher when an interpreter was used, significantly so for one verbal test. These findings suggest that neuropsychologists should avoid interpreter use whenever possible, particularly for tests with high demands on interpreter abilities and skills.