A commentary on Liang et al.'s paper with regard to emerging views of memory assessment in Alzheimer's disease

Liang et al. (2016) reported on a study carried out to investigate whether Alzheimer's disease in its familial variant (FAD) affects visual short-term memory (VSTM) for integrated representations comprising visuospatial information i.e., object and location. This is the second study investigating VSTM binding abilities in symptomatic and pre-symptomatic cases of FAD. An earlier study investigated VSTM for integrated representations comprising surface features such as shapes and colours (Parra, Abrahams, Logie, Mendez, et al., 2010). The memory function investigated by Liang et al. (2016) is known as “relational binding” whereas that one investigated by Parra, Abrahams, Logie, Mendez, et al. (2010) is known as “conjunctive binding”. Visuospatial relational binding deficits in long-term memory (LTM), also known as associative learning impairments, have been previously reported in cases of sporadic AD (SAD) in the clinical (Swainson et al., 2001) and prodromal stages (Fowler, Saling, Conway, Semple, & Louis, 2002). Parra, Abrahams, Logie, and Della Sala (2010) have reported VSTM conjunctive binding deficits in SAD. Taken together, the results from these studies suggest that AD affects memory binding abilities regardless of the variant of the disease, the memory system where bound representations are held, or the nature of such representations (i.e., shapes, colours, locations).The evidence drawn from rare cases of FAD is expected to support research into AD broadly. I will therefore focus my commentary on memory assessment in AD as a disorder affecting people at different ages. Particularly, I will focus on four areas on which Liang et al.’s study motivates debate: (1) format and structure of memory, (2) the effect of age on memory representations, (3) memory at the boundaries between normal and abnormal ageing, and (4) a new memory paradigm for the early detection of AD.