Does a rabbit have feathers or fur? Development of a 42-item semantic memory test (SMT-42).

ABSTRACT

OBJECTIVE: We present the preliminary study of the 42-item Semantic Memory Test (SMT-42), a test developed to distinguish semantic variant primary progressive aphasia (svPPA) from the other variants logopenic (lPPA) and nonfluent/agrammatic (naPPA). The test requires the patient to retrieve the conceptual features of items belonging to different lexical categories. METHODS: In the first study, we administered the French version of the SMT-42 to a population of healthy subjects and to patients with svPPA matched to a subgroup of the healthy subjects. In the second study, we administered the SMT-42 to four groups of patients (with svPPA, lPPA, naPPA and Alzheimer's disease [AD], respectively) to study its capacity to differentiate patients suffering from svPPA from the other patients. RESULTS: In the first study, 109 healthy subjects were included, 15 of whom were paired with 15 subjects presenting with svPPA. In the second study, designed to compare groups presenting a primary progressive aphasia variant and AD, 12 subjects with svPPA, 6 with naPPA and 9 with lPPA were included, along with 21 subjects with AD. The subjects presenting a semantic deficit were clearly distinguished from the others by their results on the SMT-42 (svPPA mean = 30.0 (5.9); lPPA mean = 37.8 (3.3), d = 1.5, p = 0.002; naPPA mean = 39.8 (1.9), d = 1.89, p = 0.001; AD mean = 38.5 (2.4), d = 1.63, p < 0.001); (svPPA median = 31; lPPA median = 38, U = 9, p = 0.002; naPPA median = 40.5, U = 1.5, p = 0.001; AD median = 39, U = 13.5, p < 0.001). CONCLUSION: The SMT-42 is simple, rapidly administered (3 minutes on average), easily scored and has good sensitivity, and it appears to be an effective tool for semantic screening in routine clinical practice.