The relationship of social isolation and sleep in older adults: evidence from cross-sectional and longitudinal studies.

OBJECTIVES: This study aimed to explore the relationship between social isolation and sleep in later life and the role of loneliness in this relationship. METHODS: In Study 1, we conducted a cross-sectional analysis of the correlation between social isolation and sleep in community-dwelling older adults (N = 108). This relationship was assessed using subjective and objective measures. Moreover, we examined the mediating role of loneliness cross-sectionally (Study 1) and longitudinally (Study 2). Longitudinal study was based on three waves of data from the National Scale Life, Health, and Aging Project (N = 1, 554). RESULTS: The results showed that social isolation was robustly associated with sleep in the general population of older adults. Specifically, subjective social isolation was associated with subjective sleep, and objective social isolation was associated with objective sleep. The results of the longitudinal study showed that loneliness mediated the reciprocal link between social isolation and sleep across time after controlling for autoregressive effects and basic demographics. CONCLUSIONS: These findings address the gap in the literature on the link between social isolation and sleep in older adults, extending the understanding of improvement in older adults' social networks, sleep quality, and psychological well-being.

Older Adults' Subjective Cognitive Decline Correlated with Subjective but Not Objective Sleep: A Mediator Role of Depression.

This study examined the relationship between older adults' subjective versus objective sleep and subjective cognitive decline (SCD), and explored the role of depression on this association. One hundred and four community-dwelling older adults underwent a week of actigraphic sleep monitoring, and completed a series of neuropsychological screeners. Older adults'SCD score was positively correlated with subjective insomnia, but not with objective sleep parameters. Further mediation modeling revealed that older adults'depression mediated the association between subjective insomnia and SCD. Subjective sleep, rather than objective sleep, may be a more sensitive indicator for older adults' SCD, with depression symptoms appearing to account for most of the variance. These findings extend our perspective on the relationship between sleep disruption and cognitive decline, and highlight the necessity of early targeted interventions on sleep to reduce the risk of cognitive impairment in the elderly with SCD.

Improving Memory through Better Sleep in Community-dwelling Older Adults: A Tai Chi Intervention Study.

OBJECTIVES: The relationship between sleep and memory has been well documented. However, it remains unclear whether a mind-body exercise, i.e., Tai Chi exercise, can improve memory performance in older adults by improving their subjective and objective sleep. METHOD: A randomized controlled trial was conducted with participants (M = 67.36, 56-79 years) randomly assigned to Tai Chi and control groups. The primary outcomes were sleep, both subjectively reported and objectively assessed by actigraphy, and memory performance, as well as the mediating role of sleep in memory improvement with Tai Chi practice. RESULTS: Tai Chi exercise led to improvements in subjective sleep, as indicated by ISI (p < 0.001, Cohen's d = 0.62) and daytime dysfunction of the PSQI (p = 0.02, Cohen's d = 0.80), and in actigraphy-assessed sleep onset latency (p < 0.01, Cohen's d = 0.61), as well as improved memory performance on digit span forward (p < 0.001, Cohen's d = 1.20) and visual spatial memory tasks (p < 0.01, Cohen's d = 0.83) compared to the control group. Importantly, Tai Chi practice improved digit span forward memory performance through parallel mediation of both subjective sleep (i.e., daytime dysfunction of the PSQI) and objective sleep (i.e., sleep onset latency; b = 0.29, p < 0.01). DISCUSSION: Our findings uncovered the potential benefits of Tai Chi exercise in relation to both subjective and objective sleep in older adults, in turn, how sleep changes played a role in the link between Tai Chi exercise and memory changes in older adults.

The Effect of Nighttime Snacking on Cognitive Function in Older Adults: Evidence from Observational and Experimental Studies.

Evidence shows that supplementary snacking could provide older adults with nutrients that cannot be obtained through three meals a day. However, whether and how supplementary snacking, especially nighttime snacking, affects older adults' cognitive function remain unclear. The present study examined the effect of nighttime snacking on cognitive function for older adults. In study 1, we investigated the association between nighttime snacking and cognitive function based on data from 2618 community-dwelling older adults from the China health and nutrition survey (CHNS). In study 2, we conducted an experiment (n = 50) to explore how nighttime acute energy intake influences older adults' performance on cognitive tasks (immediate recall, short-term delayed recall, and long-term delayed recall). Both the observational and experimental studies suggested that nighttime snacking facilitated older adults' cognitive abilities, such as memory and mathematical ability, as indicated by subjective measures (study 1) and objective measures (studies 1 and 2). Moreover, this beneficial effect was moderated by cognitive load. These findings bridge the gap in the literature on the relationships between older adults' nighttime snacking and cognitive function, providing insight into how to improve older adults' dietary behaviors and cognitive function.

[Vasoactive intestinal peptide expression and its clinical significance in gastric adenocarcinoma].

OBJECTIVE: To investigate the expression of vasoactive intestinal peptide (VIP) in gastric adenocarcinoma, and to evaluate the correlation of VIP level with clinical pathologic parameters. METHODS: The level of VIP in sera from gastric adenocarcinoma patients and healthy people was investigated by ELISA. Moreover, the differential gene expression between gastric adenocarcinoma, gastric dysplasia, and the corresponding normal gastric mucosa were determined by RT-PCR. Western Blot was also used to measure the expression of VIP in the gastric adenocarcinoma and the normal gastric mucosa. RESULTS: The serum level of VIP was (5.794 +/- 0.014) ng/ ml in normal control and was (14.437 +/- 0.825) ng/ml in gastric adenocarcinoma patients, showing significant difference (P < 0.05). Meanwhile,the V/B of gastric adenocarcinoma tissues was greater than that of gastric dysplasia and the corresponding normal gastric mucosa (P <0.01), the values of V/B were 1.5261 +/- 0.3028, 0.9334 +/- 0.2872,and 0.9051 +/- 0.2794, respectively. The values of V/B between normal gastric mucosa and gastric dysplasia were not different significantly (P > 0.05). There were significantly negative correlation between the VIP mRNA expression of the differentiation degree of tumor (P < 0.05). The VIP mRNA expression was higher in gastric adenocarcinoma with lymph node metastasis than that without lymph node matastsis (P < 0.05). The VIP protein expression of the gastric adenocarcinoma tissues was greater than that of normal control. CONCLUSION: This findings provide a direct evidence to support the possibility that VIP play a cofactor role in the pathogenesis of gastric adenocarcinoma.