Short-term memory conjunctive binding in subjective cognitive decline: A PET biomarker-based study

The Short-Term Memory Conjunctive Binding (STMCB) test assesses the ability to maintain integrated shape-colour associations in memory. It has been applied to detect Alzheimer's disease (AD) across the continuum, from preclinical stages and subjective cognitive decline (SCD) to dementia. The objective of the present study was to examine whether the STMCB test can differentiate individuals at very early stages of AD from controls. The sample included 67 participants with normal performance on standard neuropsychological tests. Participants were classified as controls or as having SCD based on self-reported memory complaints. Twenty-three controls and 44 individuals with SCD completed the STMCB test. All individuals also underwent a comprehensive neuropsychological evaluation, amyloid ([¹¹C]PIB) and FDG-PET scans. No significant group differences were observed in STMCB test performance between the groups. Furthermore, the STMCB test did not distinguish between amyloid-negative controls and SCD participants with amyloid pathology. These findings suggest that binding deficits may emerge later in the AD continuum, particularly when tau deposition or neurodegeneration is present.