Cognitive Vulnerability to Stress in Individuals at Risk for Alzheimer's Disease

In the wake of discouraging results from treatment trials in Alzheimer's disease (AD), there is emerging consensus that the lack of efficacy in these trials is attributable to heterogeneity in the course of AD. Among the potential causes of heterogeneity, the investigators aim to focus on vulnerability to acute stress. Although associations between stress and the risk of AD are well established, these findings have not been used to inform AD intervention efforts. The investigators aim to address this crucial gap. Considering that in healthy individuals, acute stress can impair cognition in those who have risk factors for AD, the investigators propose that these individuals may represent a specific endophenotype who could be targeted for AD treatment trials. The investigators' prior findings implicate the endocrine stress response as an important component of AD risk that warrants further study. The investigators aim to conduct a prospective study to examine the associations among the acute endocrine stress response, cognitive impairment following acute stress, and subsequent cognitive decline. For the investigators' basic study design, the investigators will induce acute stress with the Trier Social Stress Test (TSST; 5 minutes of public speaking and 5 minutes of mental arithmetic) and then administer a battery of cognitive tests. Two cognitive domains-memory and executive functioning-will be the primary cognitive outcomes. Salivary samples collected at fixed intervals will be used to measure stress hormone response; cortisol will the primary endocrine hormone outcome. The investigators will also examine the influence of apolipoprotein E (APOE) gene polymorphisms and polygenic risk scores, conduct sex-stratified analyses, and collect blood-based biomarkers for AD. The investigators' study has 3 primary aims: 1. To determine the association between endocrine response to acute stress and memory and executive test performance following acute stress in individuals with MCI due to AD. 2. To examine the moderating effect of APOE genotype and polygenic risk score derived from genome wide genotyping on the association between endocrine response to acute stress and cognitive test performance following acute stress in individuals with MCI due to AD. 3. To determine predictors of cognitive decline and neurodegeneration at 2-year follow-up. Secondary Aims: Conduct the analyses from Specific Aims 1-3 in men and women separately in order to identify sex-specific predictors of stress-induced memory and executive impairment and cognitive decline after 2 years. As an exploratory aim, the investigators will examine the influence of personality factors and stressful life events on the hypothesized associations. For this study, participants will come to the clinic for 3 study visits. For the first visit, participants will be asked to bring someone who knows the participant well (a "study partner"). During that visit, participants and the participants' study partners will answer questions about the participant's daily functioning. In addition, participants (but not the participants study partners) will take paper-and-pencil tests and provide a blood sample. About one month later, participants will return for a second study visit, but the participants' study partner does not need to come to that visit. During that second visit, participants will undergo a brief procedure (public speaking and mental math) that is designed to cause stress, during which the investigators will measure participants' stress hormones by asking participants to provide the investigators with samples of the participants' saliva. Two years later, participants and the participants' study partners will return for Visit 3. At that visit, the investigators will ask participants to provide another blood sample and complete tests of memory and other thinking skills. Study partners will answer questions about the participants during this visit but will not take any tests or provide a blood sample.