Biology subjects

Sattari, N.

Publications and source records attributed to Sattari, N..

4 recordsLinked to original sources

bioRxiv2026

Longitudinal Alterations in Sleep EEG Biomarkers of Memory Consolidation in Middle-Aged and Older Adults

The precise coordination of slow oscillations (SO) and sleep spindles during non-rapid eye movement (NREM) sleep supports memory consolidation and may serve as a sensitive marker of cognitive aging. However, longitudinal changes in their oscillatory dynamics in midlife and older age remain poorly understood. Using polysomnography with high-density EEG at two timepoints over [~]2.5 years, we examined changes in local NREM slow wave (SW), sleep spindle (occurring in the 11-16 Hz sigma range), and SO-sigma coupling strength in cognitively unimpaired middle-aged to older adults at risk for Alzheimers disease. Fronto-central SO-sigma power coupling strength significantly declined over time, independent of changes in multiple measures of SW and sleep spindle expression. Local declines in multiple sleep spindle measures were also observed. Greater baseline levels of cerebrospinal fluid (CSF) neurogranin, a postsynaptic protein abundantly expressed in the dendritic spines of the hippocampus and cerebral cortex and implicated in calcium-dependent synaptic plasticity, predicted the magnitude of longitudinal decline in SO-fast sigma coupling strength, which in turn predicted episodic memory performance changes. These findings suggest that longitudinal changes in local sleep oscillatory dynamics are related to decreased synaptic integrity and may serve as an early indicator of memory decline in older adults at risk for Alzheimers disease.

neuroscience↗

bioRxiv2024

Engagement in moderate-intensity physical activity supports overnight emotional memory retention in older adults

ImportancePreserving the ability to vividly recall emotionally rich experiences contributes to quality of life in older adulthood. While prior work suggests that moderate-intensity physical activity (MPA) may bolster memory, it is unclear whether this extends to emotionally salient memories consolidated during sleep. ObjectiveTo investigate associations between engagement in physical activity (PA) and overnight emotional memory retention and examine whether theoretically replacing 30-minutes of lower-intensity activity with MPA is associated with better consolidation. Design, Setting, and ParticipantsA cross-sectional study of 40 community-dwelling older adults free of neurological and psychiatric disorders. Data were collected from May 2018 to July 2022 and analyzed from January to July 2024. ExposuresParticipants completed an overnight polysomnography (PSG) with emotional memory tested before and after sleep and a self-report questionnaire assessing habitual PA. Main Outcome(s) and Measures(s)Emotional memory performance was assessed via recognition memory or mnemonic discrimination performance. Overnight memory retention was calculated by subtracting immediate test from delayed test performance for both recognition memory and mnemonic discrimination, with more negative scores indicating lower memory retention. Frequency and duration of MPA, light-intensity PA, non-exertive activity, and sedentary behavior were calculated from the Community Health Activities Model Program for Seniors (CHAMPS) Activities Questionnaire for Older Adults. Isotemporal substitution modelling evaluated whether statistically reallocating time spent in sedentary and lower-intensity activity to MPA was associated with better overnight memory retention. ResultsData from 40 participants were analyzed ({square}age=72.3{+/-}5.8, 26 female). Better overnight emotional recognition memory retention was associated with the frequency ({beta}=0.663, SE=0.212, p=0.003) and duration ({beta}=0.214, SE=0.101, p=0.042) of MPA. No relationships were found with mnemonic discrimination or neutral recognition memory. Statistically modelling the replacement of 30 minutes of lower-intensity activity with MPA was associated with better overnight retention of emotional memories ({beta}=0.108, SE=0.048, p=0.030), but not neutral ({beta}=-0.029, SE=0.069, p=0.679). Conclusions and RelevanceMPA may enhance sleep-dependent consolidation of emotional memories in older adults. Modest increases in MPA may yield significant benefits for sleep-dependent emotional memory retention. These findings may guide interventions to preserve memory function and inform public health recommendations by demonstrating that substituting even short durations of low-intensity activity for MPA could produce significant cognitive gains relevant for maintaining quality of life in older adulthood.

neuroscience↗

bioRxiv2020

Age-related differences in Autonomic/Central Coupling during a Daytime Nap

Age-dependent functional changes are mirrored by declines in both the central the autonomic nervous systems and have been related to pathological aging. Prior studies in our group have identified a temporal coupling of Autonomic and Central Events (ACEs) during sleep using electrocardiogram to measure heart rate and electroencephalography to measure brain rhythms, with heart rate bursts (HRBs) temporally coincided with increased slow-wave-activity (SWA, 0.5-1Hz) and sigma activity (12-15Hz), followed by parasympathetic surge (RRHF) during non-rapid eye movement (NREM) sleep. ACEs predicted working memory (WM) improvement in young adults. Given that there are paralleling age-related declines in both the ANS and CNS, the current study investigated differences in ACE activity during daytime sleep in older and younger adults and their functional impact on working memory. Compared to youngers, older adults showed lower amplitude of ACEs during NREM sleep, but no age-related difference during Wake. Furthermore, while younger adults demonstrated a parasympathetic surge after HRBs, older adults showed a different pattern, with a earlier rise and maintenance of the RRHF. Finally, we examined whether ACE predicted WM in older adults. We found that older adults with good WM show stronger coupling, whereas low WM performers had less robust ACE activity. Taken together, our results demonstrated that autonomic-central coupling declines with age, with possible links to deterioration in WM function. Given that age-related deterioration in autonomic and central nervous system activity is implicated in pathological decline, the current findings may facilitate novel insights to the cognitive neuroscience of aging.

neuroscience↗

bioRxiv2020

Age-related losses in cardiac autonomic activity during a daytime nap

In healthy, young individuals, a reduction in cardiovascular output and a shift from sympathetic to parasympathetic (vagal) dominance is observed from wake into stages of nocturnal and daytime sleep. This cardiac autonomic profile, measured by heart rate variability (HRV), has been associated with significant benefits for cardiovascular health. Aging is associated with decreased nighttime sleep quality and lower parasympathetic activity during both sleep and resting. However, it is not known whether age-related dampening of HRV extends to daytime sleep, diminishing the cardiovascular benefits of naps in the elderly. Here, we investigated this question by comparing the autonomic activity profile between young and older healthy adults during a daytime nap and a similar period of wakefulness (quiet wake; QW). For each condition, from the electrocardiogram (ECG), we obtained beat-to-beat HRV intervals (RR), root mean square of successive differences between adjacent heart-beat-intervals (RMSSD), high frequency (HF), low frequency (LF) power and total power (TP), HF normalized units (HFnu), and the LF/HF ratio. As previously reported, young subjects showed a parasympathetic dominance during NREM, compared with REM, pre-nap rest, and WASO. On the other hand, older, compared to younger, adults showed significantly lower vagally-mediated HRV (measured by RMSSD, HF, HFnu) during NREM. Interestingly, however, no age-related differences were detected during pre-nap rest or QW. Altogether, our findings suggest a sleep-specific reduction in parasympathetic modulation that is unique to NREM sleep in older adults.Impact Statement Sleep is naturally modulated by the autonomic nervous system (ANS), with greater dominance of parasympathetic over sympathetic activity during non-rapid-eye-movement (NREM) sleep. As such, sleep has been termed a “cardiovascular holiday” and has been associated with positive health outcomes. Aging, however, is linked to decreases in cardiac autonomic activity and sympathovagal imbalance. While the impact of aging on ANS activity during nocturnal sleep has received some attention, the cardiac profiles during a daytime nap, to our knowledge, have not yet been studied under the context of aging. Herein, young adults demonstrated increased parasympathetic activity during deep sleep. Older adults, however, showed less parasympathetic modulation during NREM sleep, suggesting loss of the cardiovascular holiday. Importantly, no age-related declines in parasympathetic activity were detected during wake, suggesting a sleep-specific reduction in parasympathetic modulation that is unique to NREM sleep in older adults.Competing Interest StatementThe authors have declared no competing interest.View Full Text

physiology↗