Task-specific and person-specific factors related to Subjective Cognitive Decline

在认知衰老领域，迫切需要确定临床前标志物

In the field of cognitive aging, there is an urgent push to identify the markers of pre-clinical Alzheimer’s disease (AD) in order to move pharmacologic intervention earlier in the disease spectrum to a time when it can be most effective. There is growing interest in subjective cognitive decline (SCD) as a potential marker of pre-clinical AD. SCD, or the perception that one’s cognition has declined despite “normal” performance on standard diagnostic testing, is an important health outcome that is concerning to many older adults, and leads some to seek medical attention. Determining the extent to which SCD may serve as a pre-clinical marker of AD is of great value, as SCD is non-invasive, inexpensive, and easily obtainable. However, SCD is a complex, multi-factorial construct. In order to determine its true utility as a marker of pre-clinical AD, it is critical to comprehensively characterize the factors that influence SCD, and that affect the degree to which SCD reflects “true” or actual cognitive functioning. Indeed, SCD is certain to reflect not only a person’s actual cognitive functioning, but also task-specific factors (i.e., how SCD is measured) and person-specific factors (e.g., how good one is at self- evaluation; how old one feels; what one believes about aging). The goals of this longitudinal proposal are to examine novel task-specific and person-specific factors that are likely to influence SCD and/or its association with actual (objectively measured) cognition in 200 older adults. A key aspect of the proposed study is the inclusion of sensitive, objective cognitive outcomes that will enable a more precise examination of the association between SCD and objective cognition than has been conducted thus far. The first objective cognitive outcome is performance on a visual short term memory (STM) binding task shown to be highly sensitive and specific to AD pathology when standard neuropsychological testing is within normal limits. We will also examine attentional control as a measure of non-memory changes that may signal early AD before memory changes are apparent in some individuals. A final critical outcome is cognitive change over time, enabling examination of subtle decline in cognition that may occur when individuals still perform within the normal range on cross-sectional testing. Taken together, these aims embody key issues recently identified by the SCD Working Group (2014) as critical for advancing the current state of knowledge on SCD, and will contribute to a novel model of SCD. Results from the proposed study will provide specific guidelines for how to assess and interpret SCD in older adults, and will set the stage for determining how and when SCD may be used as an indicator of preclinical Alzheimer’s disease.