It has been challenging to identify clinical cognitive markers that can differentiate patients with Alzheimer's disease (AD) from those with behavioral variant frontotemporal dementia (bvFTD). The short-term memory binding (STMB) test assesses the ability to integrate colors and shapes into unified representations and to hold them temporarily during online performance. The objective of this study is to investigate whether free recall deficits during short-term memory binding (STMB) test can differentiate patients with AD from those with bvFTD and controls. Participants were 32 cognitively intact adults, 35 individuals with AD and 18 with bvFTD. All patients were in the mild dementia stage. Receiver-operating characteristic (ROC) analyses were used to examine the diagnostic accuracy of the STMB. The results showed that AD patients performed significantly worse than controls and bvFTD patients in the STMB test, while the latter groups showed equivalent performance. The bound condition of the STMB test showed an AUC of 0.853, with 84.4% of sensitivity and 80% of specificity to discriminate AD from controls and an AUC of 0.794, with 72.2% of sensitivity and 80% of specificity to differentiate AD from bvFTD. Binding deficits seem specific to AD. The free recall version of the STMB test can be used for clinical purposes and may aid in the differential diagnosis of AD. Findings support the view that the STMB may be a suitable cognitive marker for AD.
Keywords: Alzheimer’s disease; Behavioral variant frontotemporal dementia; Differential diagnosis; Memory binding; Short-term memory.