Objectives: To evaluate the sensitivity of the CAMCOG naming subscale to anomia in Alzheimer's disease (AD) patients identified as anomic on the Boston Naming Test (BNT); and to compare the sensitivities of BNT, category (semantic) fluency (CF), and episodic memory (Delayed Word Recall, DWR) in detecting AD.
Method: Data from 140 probable AD patients (NINCDS/ADRDA) were analysed. Anomic AD patients were identified (BNT) and the sensitivity to anomia of the CAMCOG naming subscale was calculated. Sensitivity (to AD) and specificity of the BNT, CF and DWR were compared in a subgroup of 60 patients age-matched to controls.
Results: On BNT 81% of ADs were classified as anomic (87% specificity). Of these anomic ADs, 23 scored 6/6 on CAMCOG naming (sensitivity = 80%), and sensitivity fell to 30% using a 5/6 cut-off. Correlation between BNT and CAMCOG naming yielded Kendall's tau = 0.48 (p<0.0001). Compared to age-matched controls BNT correctly classified 70% of ADs and 87% of controls (overall accuracy = 77%). On CF 68% of ADs and 83% of controls were correctly classified (overall accuracy = 72%). BNT and CF were moderately correlated (r = 0.49, p<0.0001). DWR correctly classified 93% ADs and 98% controls (overall accuracy = 95%).
Conclusions: Given its brevity, we recommend the inclusion of a split-half form of the BNT in screening test batteries for the detection of AD. The observed pattern of cognitive impairment is consistent with current models in which semantic memory deficits occur in AD only when the neuropathology extends beyond the entorhinal/hippocampal region to the temporal neocortex.