Faculty Bibliography

Poor cardiovascular health is strongly linked to increased risk of cognitive impairment and Alzheimer's disease and related dementias. This commentary discusses Yang and associates' work on the associations between cardiovascular health in middle age, as defined by Life Essential 8 scores, and later digital cognitive performance and incident Alzheimer's disease. We examine the strengths and weaknesses of their study within the broader research context. We emphasize the potential significance of sleep and stress the need for longitudinal studies incorporating robust neuropsychiatric methodologies, advanced neuroimaging techniques, and diverse participant samples to enhance the reliability and generalizability of results.

Obstructive sleep apnea (OSA) exerts pathogenic effects through a combination of sleep fragmentation (SF) and intermittent hypoxia (IH). The mechanisms through which sleep disruption impacts memory might arise by investigating disruption of specific sleep stages and, when such disruption occurs through OSA, by evaluating the individual contributions of SF and IH. Given region-specific EEG slow activity during non-REM sleep has been associated with overnight declarative, motor and spatial memory formation, we investigated the effects of disrupting slow wave sleep (SWS) on a virtual maze navigation task. Thirty three participants (24 male, 56 years old [range 28-68 years] with OSA (baseline AHI4%>20/hour) who were habitually well-treated and adherent to CPAP completed 3 timed trials on a 3D spatial maze before and after polysomnographically (PSG) recorded sleep. We restricted CPAP withdrawal to SWS through real-time monitoring of the PSG under three conditions: 1) stable-SWS on therapeutic CPAP, 2) SWS-CPAP withdrawal containing SF and IH, and 3) SWS-CPAP withdrawal with supplemental oxygen containing SF with reduced IH. SWS-specific CPAP withdrawal (with or without supplemental oxygen) did not significantly impact EEG slow oscillation or spatial navigational memory, despite effectively reducing %SWS and SWS bout length. Greater regional EEG slow oscillation (0.6-1Hz), but not delta (1-4Hz) activity, was associated with improvements in overnight memory during stable SWS in the CPAP condition. These observations suggest that slow oscillations may be important for overnight memory processing, and sleep disruptions of sufficient magnitude to reduce slow oscillations may be required to capture demonstrable change in spatial navigation performance.

Alzheimer's disease rates are expected to triple by 2050. Early detection and specific mitigation efforts are warranted to blunt the alarming increase. Physical function index (PFI) declines with age; additionally, higher PFI is associated with better cognitive functioning in middle-to-older age individuals. However, most studies utilize one domain of PFI to examine associations with cognition. Therefore, using clustering methods, the purpose of this investigation was to determine if high-risk individuals with higher PFI have better cognitive outcomes compared to individuals with lower PFI. Participants (n = 215; 73.1% female; 45-75 years) completed a body mass scan, venous blood draw, 7 PFI tasks, and 7 cognitive tests. A k-means cluster analysis was utilized to identify PFI cluster for participants, one-way ANCOVAs were used to assess differences in cognition among clusters. Cluster 1 (C1; n = 29) was characterized as the highest strength/power, faster dual-task walking time, and higher aerobic capacity, Cluster 3 (C3; n = 113) had the lowest values between PFI groups, Cluster 2 (C3; n = 74) was in-between C1 and C3. Individuals in C1 had significantly higher global cognitive, visuospatial scores, digital executive functioning and associative learning compared to individuals in C3 (p < 0.05). Individuals in C1 and C2 had significantly higher values on orientation task and figure recall than individuals in C3 (p < 0.05). The results from this current study demonstrate that individuals with higher combined PFI output have higher global cognitive scores than individuals with lower combined PFI output. Examining PFI variables together may be a valuable tool when assessing cognition among cognitively at-risk individuals.

Anxiety is highly prevalent in Alzheimer's disease (AD), correlating with cerebrospinal fluid/positron emission tomography biomarkers and disease progression. Relationships to plasma biomarkers are unclear. Herein, we compare levels of plasma biomarkers in research participants with and without anxiety at cognitively normal, mild cognitive impairment, and AD dementia stages. We observed significantly higher plasma tau/amyloid-β₄₂ ratio in AD participants with anxiety versus those without, but did not observe differences at other stages or plasma biomarkers. No such relationships were evident with depression. These results support a unique pathophysiological relationship between anxiety and AD that can be reflected in plasma biomarkers, suggestive of heightened neurodegeneration.

BACKGROUND:Although related, the precise mechanisms linking obstructive sleep apnea (OSA) and cardiovascular disease (CVD) are unclear. Platelets are mediators of CVD risk and thrombosis and prior studies suggested associations of OSA and platelet activity. The aim of this study is to assess the link between OSA, platelet activity, and CVD-related risk factors. METHODS AND RESULTS/RESULTS:=0.002). No associations were detected in nonaspirin users (n=417). CONCLUSIONS:No associations were detected between OSA and platelet aggregation in a community sample. Our finding that OSA associates with increased platelet aggregation in the aspirin group, most of whom use it for primary prevention of CVD, suggests that platelet aggregation may mediate the adverse impact of OSA on vascular health in individuals with existing CVD risk, supporting further investigation.

OBJECTIVE/UNASSIGNED:The purpose of this study was to determine whether social support from extended family and church members moderate the association between chronic stress exposure and sleep quality in a nationally representative sample of African American adults. DESIGN/UNASSIGNED:Data from African American respondents aged 18 and older were drawn from the National Survey of American Life-Reinterview. The analytic sample for this study included 1,372 African American adults who attended religious services at least a few times a year, as the church-based relationship measures were only assessed for these individuals. Self-reported sleep quality was assessed by sleep satisfaction, trouble falling asleep, and restless sleep. Chronic stress exposure was measured by a nine-item index. OLS and logistic regression were used to estimate the relationship between chronic stress exposure, extended family and church relationships, and sleep quality. RESULTS/UNASSIGNED:The data indicated that chronic stress exposure was associated with decreased sleep satisfaction, increased likelihood of trouble falling asleep and restless sleep. Receiving emotional support from family and more frequent contact with church members were associated with decreased restless sleep. Emotional family support moderated the associations between chronic stress exposure and trouble falling asleep and restless sleep. The positive associations between chronic stress exposure and these two sleep quality measures were attenuated among respondents who received high levels of emotional support from their family. CONCLUSIONS/UNASSIGNED:Together, these findings underscore the detriment of chronic stress exposure to African Americans' sleep quality and suggest that extended family members are effective stress coping resources and play an important role in this population's sleep quality.

BACKGROUND:Subjective cognitive decline (SCD), considered a preclinical dementia stage, is less understood in Hispanics, a high-risk group for dementia. We investigated SCD to mild cognitive impairment (MCI) progression risk, as well as baseline and longitudinal features of depressive symptoms, SCD complaints, and objective cognitive performance among Hispanics compared to non-Hispanic Whites (NHW). METHODS:Hispanic (n = 23) and NHW (n = 165) SCD participants were evaluated at baseline and 2-year follow-up. Evaluations assessed function, depressive symptoms, SCD, and objective cognitive performance. RESULTS:Hispanic ethnicity associated with a significantly increased risk of 2-year progression of SCD to MCI compared to NHW. This increased risk associated with increased depressive symptoms, distinctive SCD features, and elevated amnestic and non-amnestic objective cognitive decline. This supports further research to refine the assessment of preclinical dementia in this high-risk group.

Laboratory polysomnography provides gold-standard measures of sleep physiology, but multi-night investigations are resource intensive. We assessed the night-to-night stability via reproducibility metrics for sleep macrostructure and electroencephalography oscillations in a group of cognitively normal adults attending two consecutive polysomnographies. Electroencephalographies were analysed using an automatic algorithm for detection of slow-wave activity, spindle and K-complex densities. Average differences between nights for sleep macrostructure, electroencephalography oscillations and sleep apnea severity were assessed, and test-retest reliability was determined using two-way intraclass correlations. Agreement was calculated using the smallest real differences between nights for all measures. Night 2 polysomnographies showed significantly greater time in bed, total sleep time (6.3 hr versus 6.8 hr, p < 0.001) and percentage of rapid eye movement sleep (17.5 versus 19.7, p < 0.001). Intraclass correlations were low for total sleep time, percentage of rapid eye movement sleep and sleep efficiency, moderate for percentage of slow-wave sleep and percentage of non-rapid eye movement 2 sleep, good for slow-wave activity and K-complex densities, and excellent for spindles and apnea-hypopnea index with hypopneas defined according to 4% oxygen desaturation criteria only. The smallest real difference values were proportionally high for most sleep macrostructure measures, indicating moderate agreement, and proportionally lower for most electroencephalography microstructure variables. Slow waves, K-complexes, spindles and apnea severity indices are highly reproducible across two consecutive nights of polysomnography. In contrast, sleep macrostructure measures all demonstrated poor reproducibility as indicated by low intraclass correlation values and moderate agreement. Although there were average differences in percentage of rapid eye movement sleep and total sleep time, these were numerically small and perhaps functionally or clinically less significant. One night of in-laboratory polysomnography is enough to provide stable, reproducible estimates of an individual's sleep concerning measures of slow-wave activity, spindles, K-complex densities and apnea severity.