An evaluation of recollection and familiarity in Alzheimer's disease and mild cognitive impairment using receiver operating characteristics

Abstract

There is a need to investigate exactly how memory breaks down in the course of Alzheimer's disease (AD). Examining what aspects of memorial processing remain relatively intact early in the disease process will allow us to develop behavioral interventions and possible drug therapies focused on these intact processes. Several recent studies have worked to understand the processes of recollection and familiarity in patients with mild cognitive impairment (MCI) and very mild AD. Although there is general agreement that these patient groups are relatively unable to use recollection to support veridical recognition decisions, there has been some question as to how well these patients can use familiarity. The current study used receiver operating characteristic (ROC) curves and a depth of processing manipulation to understand the effect of MCI and AD on the estimates of recollection and familiarity. Results showed that patients with MCI and AD were impaired in both recollection and familiarity, regardless of the depth of encoding. These results are discussed in relation to disease pathology and in the context of recent conflicting evidence as to whether familiarity remains intact in patients with MCI. The authors highlight differences in stimuli type and task difficulty as possibly modulating the ability of these patients to successfully use familiarity in support of memorial decisions.

Figure 1

Aggregate ROC curves for (1A) controls, (1B) MCI patients, and (1C) AD patients. The curves with rectangular points represent the ROCs for deeply encoded items while the lines with triangular points represent the ROCs for shallowly encoded items.

Figure 1

Aggregate ROC curves for (1A) controls, (1B) MCI patients, and (1C) AD patients. The curves with rectangular points represent the ROCs for deeply encoded items while the lines with triangular points represent the ROCs for shallowly encoded items.

Figure 2

YHT model-generated estimates of familiarity (d’) and recollection (R) for deeply and shallowly encoded items for controls, MCI patients, and AD patients. Error bars represent the standard error of the mean.