Aging Stereotypes and Prodromal Alzheimer's Disease

Mild Cognitive Impairment (MCI)

Because of the lengthening of life expectancy, more and more people are concerned with the effects of aging on their mental faculties (e.g., memory decline) and with the possibility of getting Alzheimer's Disease (AD) or other forms of dementia. This increasing awareness of AD has already resulted in a growing demand for neuropsychological testing. AD's research also emphasizes the need for early screening to improve the prediction of the disease progression and the efficacy of any future therapy. Such a drive to screen for pre-dementia raises the challenging issue of frontline identification of individuals in the preclinical or early clinical stages of AD. Mild Cognitive Impairment (MCI) is typically considered to be the prodromal state of AD, and is therefore at the core of the drive for early screening. Moreover, Pre-MCI so called SCI (Subjective Cognitive Impairment) can precede AD for 15 years. However, many individuals diagnosed with MCI do not convert to AD, some remaining stable and others even reversing back to normal (with rates of reversion to normal varying from 4.5% to as high as 53%). This over-diagnosis bias, which has been largely overlooked, is at the core of the present project at the interface of human and life sciences. Here, we argue that an important source of overdiagnosis in the prodromal state of AD comes from negative aging stereotypes (e.g., the culturally shared beliefs that aging inescapably causes severe cognitive decline and diseases such as AD) that permeate neuropsychological screening. There is ample evidence in the laboratory that such stereotypes contribute to the differences observed in the healthy population between younger and older adults in explicit memory tasks. Additionally, three pilot (lab) studies specifically conducted for the present ANR project showed that the threat of being judged stereotypically undermines the controlled use of memory of healthy older adults and simultaneously intensifies their automatic response tendencies, resulting in impaired memory performance. The present proposal goes several steps further by examining for the first time whether aging stereotypes are powerful enough to implicitly permeate the clinical neuropsychological testing and thus inflate memory deficits in older adults judged at risk (based on either epidemiological criteria or memory complaints), resulting in false-positive detection of SCI and MCI. This provocative hypothesis will be tested while 1) using biomarkers of neurodegeneration to distinguish false-positives from true MCI, and 2) using biomarkers of stress to examine whether and how aging stereotypes can lead to acute physiological stress during neuropsychological testing. This innovative project has the potential to offer new recommendations to improve the diagnosis accuracy of prodromal state of AD, with positive consequences for older people's wellbeing.

France