Preliminary Evidence -- Diagnosed Alzheimer's Disease But Not MCI Affects Working Memory Capacity - 0.7 of 2.7 Memory Slots is Lost

TL;DR

This study shows that diagnosed Alzheimer's disease reduces working memory capacity by approximately 0.7 slots, as measured by the Tarnow Unchunkable Test, potentially aiding diagnosis and targeted therapy.

Contribution

It introduces the use of the Tarnow Unchunkable Test to specifically measure working memory loss in Alzheimer's disease, distinguishing it from MCI and normal aging.

Findings

Diagnosed Alzheimer's correlates with a loss of 0.7 memory slots.

The TUT effectively differentiates Alzheimer's from MCI.

Working memory capacity reduction may inform diagnosis and treatment strategies.

Abstract

Recently it was shown explicitly that free recall consists of two stages: the first few recalls empty working memory (narrowly defined) and a second stage, a reactivation stage, concludes the recall (Tarnow, 2015). It was also shown that the serial position curve changes in mild Alzheimer's disease, lowered total recall and lessened primacy, are similar to second stage recall and different from recall from working memory. The Tarnow Unchunkable Test (TUT, Tarnow, 2013) uses double integer items to separate out only the first stage, the emptying of working memory, by making it difficult to reactivate items due to the lack of intra-item relationships. Here it is shown that subject TUT selects out diagnosed Alzheimer's Disease but not MCI. On average, diagnosed Alzheimer's Disease is correlated with a loss of 0.7 memory slots (out of an average of 2.7 slots). The identification of a lost memory slot may have implications for improved stage definitions of Alzheimer's disease and for remediation therapy via working memory capacity management. In conjunction with the Alzheimer's disease process map, it may also be useful to identify the exact location of working memory.