Language and behavior domains enhance the value of the clinical dementia rating scale

Background: The six domain standard Clinical Dementia Rating Scale (CDRstd) has been successful for staging patients with the clinical syndrome of probable Alzheimer's disease (AD). The CDRstd does not specifically address language dysfunction or alteration in personality and social behaviors which are prominent in behavioral variant frontotemporal dementia (bvFTD) and primary progressive aphasia (PPA). Objective: To determine the value of adding domains of Language (LANG), and Behavior, Comportment, and Personality (BEHAV) to the CDRstd for the evaluation of patients with bvFTD and PPA. Methods: Two new domains, LANG and BEHAV, were constructed to parallel the six domains sampled in the CDRstd. Clinical and neuropsychological test data were obtained from the National Alzheimer's Coordinating Center. The dataset contained information on 2550 probable AD, 88 vascular dementia, 281 dementia with Lewy body, 234 bvFTD, and 137 PPA patients. Results: There were 76.5% of bvFTD and 99.3% of PPA patients with abnormal ratings (>0) on the LANG domain; 90.2% of bvFTD and 63.5% of PPA had abnormal ratings on the BEHAV domain. In patients with a CDRstd sum of boxes score of <4, 53.7% of bvFTD had BEHAV domain and 78.6% of PPA patients had LANG domain scores >1. Among probable AD patients, 3.7% had LANG ratings that were ≥1 and 3.8% had BEHAV ratings that were ≥1. Logistic regression analyses showed that adding either the LANG or BEHAV domains to the CDRstd sum of boxes score significantly improved the discrimination between probable AD, bvFTD, and PPA. Conclusions: The new LANG and BEHAV domains add value to the CDRstd for the characterization of the nonamnestic symptoms that are prominent in patients with bvFTD and PPA but that also occur in those with probable AD.