Normative Symbol Digit Modalities Test performance in a community-based sample

The Symbol Digit Modalities Test [SDMT; Smith, A. (1982). Symbol Digit Modalities Test. Los Angeles: Western Psychological Services; Smith, A. (1968). The symbol-digit modalities test: a neuropsychologic test of learning and other cerebral disorders. In J. Helmuth (Ed.), Learning disorders (pp. 83–91). Seattle: Special Child Publications] is a substitution task that is the inverse of the Digit Symbol Test [Wechsler, D. (1955). Manual for the Wechsler Adult Intelligence Scale (WAIS). New York: The Psychological Corporation]. The familiar task of filling numbers in boxes, and the availability of an oral administration, make this a popular screening instrument for brain impairment. Normative data were previously reported for a variety of clinical groups, but complete information on non-clinical samples across age, education, gender, and socioeconomic status is limited. The present study examines the performance of a community-dwelling control sample across age, education, gender, and income groupings. In a multivariate model, these four variables did not impact test performance. These results support the utilization of the SDMT as a robust screening test for adult neuropsychological impairment.