High-Resolution Spectral Sleep Analysis Reveals a Novel Association Between Slow Oscillations and Memory Retention in Elderly Adults

Objective: In recognition of the mixed associations between traditionally scored slow wave sleep and memory, we sought to explore the relationships between slow wave sleep, electroencephalographic (EEG) power spectra during sleep and overnight verbal memory retention in older adults. Design, Setting, Participants, and Measurements: Participants were 101 adults without dementia (52% female, mean age 70.3 years). Delayed verbal memory was first tested in the evening prior to overnight polysomnography (PSG). The following morning, subjects were asked to recall as many items as possible from the same List (overnight memory retention; OMR). Partial correlation analyses examined the associations of delayed verbal memory and OMR with slow wave sleep (SWS) and two physiologic EEG slow wave activity (SWA) power spectral bands (0.5–1 Hz slow oscillations vs. 1–4 Hz delta activity). Results: In subjects displaying SWS, SWS was associated with enhanced delayed verbal memory, but not with OMR. Interestingly, among participants that did not show SWS, OMR was significantly associated with a higher slow oscillation relative power, during NREM sleep in the first ultradian cycle, with medium effect size. Conclusions: These findings suggest a complex relationship between SWS and memory and illustrate that even in the absence of scorable SWS, older adults demonstrate substantial slow wave activity. Further, these slow oscillations (0.5–1 Hz), in the first ultradian cycle, are positively associated with OMR, but only in those without SWS. Our findings raise the possibility that precise features of slow wave activity play key roles in maintaining memory function in healthy aging. Further, our results underscore that conventional methods of sleep evaluation may not be sufficiently sensitive to detect associations between SWA and memory in older adults

Neurocognitive markers of passive suicidal ideation in late-life depression

Objectives: (1) To delineate whether cognitive flexibility and inhibitory ability are neurocognitive markers of passive suicidal ideation (PSI), an early stage of suicide risk in depression and (2) to determine whether PSI is associated with volumetric differences in regions of the prefrontal cortex (PFC) in middle-aged and older adults with depression. Design: Cross-sectional study. Setting: University medical school. Participants: Forty community-dwelling middle-aged and older adults with depression from a larger study of depression and anxiety (NIMH R01 MH091342-05 PI: O\u27Hara). Measurements: Psychiatric measures were assessed for the presence of a DSM-5 depressive disorder and PSI. A neurocognitive battery assessed cognitive flexibility, inhibitory ability, as well as other neurocognitive domains. Results: The PSI group (n = 18) performed significantly worse on cognitive flexibility and inhibitory ability, but not on other neurocognitive tasks, compared to the group without PSI (n = 22). The group with PSI had larger left mid-frontal gyri (MFG) than the no-PSI group. There was no association between cognitive flexibility/inhibitory ability and left MFG volume. Conclusions: Findings implicate a neurocognitive signature of PSI: poorer cognitive flexibility and poor inhibitory ability not better accounted for by other domains of cognitive dysfunction and not associated with volumetric differences in the left MFG. This suggests that there are two specific but independent risk factors of PSI in middle- and older-aged adults

Subjective but not objective sleep is associated with subsyndromal anxiety and depression in community-dwelling older adults

To examine the relationship between subclinical anxiety and depressive symptoms and objective sleep architecture measures and subjective sleep reports in older adults.Community-dwelling older adults (N = 167) self-rated their current severity of anxiety symptoms, depressive symptoms, daytime sleepiness, and global sleep quality. Participants received overnight ambulatory polysomnography to assess sleep architecture. Multivariate linear regression models examined associations between anxiety and depressive symptoms and objective and subjective sleep measures.Significant findings emerged for subjective sleep, with higher depression and anxiety scores associated with worse global sleep quality and greater anxiety scores associated with greater daytime sleepiness. No significant associations were observed between subclinical levels of anxiety or depressive symptoms with sleep architecture.Subclinical levels of late-life anxiety and depression have distinct associations with subjective sleep disturbance. Findings implicate subjective measures of sleep quality and daytime sleepiness as stronger trait markers for subthreshold psychiatric symptoms than objective sleep biomarkers