[Sleep and circadian rhythms in ageing]

Geriatric patients with cognitive impairment

BACKGROUND

Hospitals are now faced with increasing numbers of cognitively impaired patients aged 80 and older who are at increased risk of treatment complications. This study concerns the outcomes when such patients are treated in a specialized ward for cognitive geriatric medicine.

METHODS

Observation of a cohort of 2084 patients from 2009 to 2014, supplemented by a sample of 380 patients from the hospital cohort of the Longitudinal Urban Cohort Ageing Study (LUCAS) for the years 2010 and 2011.

RESULTS

Geriatric inpatients with cognitive impairment tend to be multimorbid. Half of the patients studied (1031 of 2084 patients) were admitted to the hospital on an emergency basis. Complications arising on the ward that necessitated transfer elsewhere arose in 2.6% (51 of 2084 patients). Moreover, analysis of the sample of 380 patients from the LUCAS cohort revealed that the treatments they underwent during hospitalization were associated with an improvement of their functional state: their mean overall score on the Barthel index rose from 39.8 ± 24.3 (median, 35) on admission to 52.7 ± 27.0 (median, 55) on discharge. The percentage of patients being treated with 5 or more drugs fell from 98.2% (373/380) on admission to 79.3% (314/362) on discharge. The percentage receiving potentially inappropriate medications (PIM), as defined by the PRISCUS list, fell from 45% to 13.3%, while the percentage of drug orders and prescriptions involving PIM fell from 7.8 % (327/4181) to 2.0% (53/2600). 70% of the patients were discharged to the same living situation where they had been before admission.

CONCLUSION

In this study, structured geriatric treatment in a cohort of older acutely ill patients with cognitive impairment was associated with improvement of functions that are relevant to everyday life, as well as with a reduction of polypharmacy. Controlled studies are needed to confirm the observed benefit.

Associations of PER3 and RORA Circadian Gene Polymorphisms and Depressive Symptoms in Older Adults

BACKGROUND

Depressive symptoms are common in older adults and associated with poor outcomes. Although circadian genes have been implicated in depression, the relationship between circadian genes and depressive symptoms in older adults is unclear.

METHODS

A cross-sectional genetic association study of 529 single nucleotide polymorphisms (SNPs) representing 30 candidate circadian genes was performed in two population-based cohorts: the Osteoporotic Fractures in Men Study (MrOS; N=270, age: 76.58±5.61 years) and the Study of Osteoporotic Fractures (SOF) in women (N=1740, 84.05±3.53 years) and a meta-analysis was performed. Depressive symptoms were assessed with the Geriatric Depression Scale categorizing participants as having none-few symptoms (0-2), some depressive symptoms (>2 to <6), or many depressive symptoms (≥6).

RESULTS

We found associations meeting multiple testing criteria for significance between the PER3 intronic SNP rs12137927 and decreased odds of reporting "some depressive symptoms" in the SOF sample (odds ratio [OR]: 0.61, 95% confidence interval [CI]: 0.48-0.78, df=1, Wald χ2=-4.04, p=0.000054) and the meta-analysis (OR: 0.61, CI: 0.48-0.78, z=-4.04, p=0.000054) and between the PER3 intronic SNPs rs228644 (OR: 0.74, CI: 0.63-0.86, z=3.82, p=0.00013) and rs228682 (OR: 0.74, CI: 0.86-0.63, z=3.81, p=0.00014) and decreased odds of reporting "some depressive symptoms" in the meta-analysis compared to endorsing none-few depressive symptoms. The RORA intronic SNP rs11632098 was associated with greater odds of reporting "many depressive symptoms" (OR: 2.16, CI: 1.45-3.23, df=1, Wald χ2=3.76, p=0.000168) in the men. In the meta-analysis the association was attenuated and nominally significant (OR: 1.63, CI: 1.24-2.16, z=3.45, p=0.00056).

CONCLUSION

PER3 and RORA may play important roles in the development of depressive symptoms in older adults.

Depressive symptoms and circadian activity rhythm disturbances in community-dwelling older women

OBJECTIVES

Aging is associated with changes in circadian rhythms. Current evidence supports a role for circadian rhythms in the pathophysiology of depression. However, little is known about the relationship between depressive symptoms and circadian activity rhythms in older adults. We examined this association in community-dwelling older women.

METHODS

We performed a cross-sectional analysis of 3,020 women (mean age: 83.55 ± 3.79 years) enrolled in the Study of Osteoporotic Fractures. Depressive symptoms were assessed with the Geriatric Depression Scale categorizing participants as "normal" (0-2; referent group, N = 1,961), "some depressive symptoms" (3-5, N = 704), or "depressed" (≥6, N = 355). Circadian activity rhythm variables were measured using wrist actigraphy.

RESULTS

In age-adjusted and Study of Osteoporotic Fractures site-adjusted models, greater levels of depressive symptoms were associated with decreased amplitude (height; df = 3,014, t = -11.31, p for linear trend <0.001), pseudo F-statistic (robustness; df = 3,014, t = -8.07, p for linear trend <0.001), and mesor (mean modeled activity; df = 3014, t = -10.36, p for linear trend <0.001) of circadian activity rhythms. Greater levels of depressive symptoms were also associated with increased odds of being in the lowest quartile for amplitude (df = 1, χ(2) = 9240, p for linear trend <0.001), pseudo F-statistic (df = 1, χ(2) = 49.73, p for linear trend <0.001), and mesor (df = 1, χ(2) = 81.12, p for linear trend <0.001). These associations remained significant in multivariate models. Post-hoc analyses comparing mean amplitude, mesor, and pseudo F-statistic values pair-wise between depression-level groups revealed significant differences between women with "some depressive symptoms" and the "normal" group.

CONCLUSION

These data suggest a graded association between greater levels of depressive symptoms and more desynchronization of circadian activity rhythms in community-dwelling older women. This association was observed even for women endorsing subthreshold levels of depressive symptoms.

Daily rhythms of the sleep-wake cycle

The amount and timing of sleep and sleep architecture (sleep stages) are determined by several factors, important among which are the environment, circadian rhythms and time awake. Separating the roles played by these factors requires specific protocols, including the constant routine and altered sleep-wake schedules. Results from such protocols have led to the discovery of the factors that determine the amounts and distribution of slow wave and rapid eye movement sleep as well as to the development of models to determine the amount and timing of sleep. One successful model postulates two processes. The first is process S, which is due to sleep pressure (and increases with time awake) and is attributed to a 'sleep homeostat'. Process S reverses during slow wave sleep (when it is called process S'). The second is process C, which shows a daily rhythm that is parallel to the rhythm of core temperature. Processes S and C combine approximately additively to determine the times of sleep onset and waking. The model has proved useful in describing normal sleep in adults. Current work aims to identify the detailed nature of processes S and C. The model can also be applied to circumstances when the sleep-wake cycle is different from the norm in some way. These circumstances include: those who are poor sleepers or short sleepers; the role an individual's chronotype (a measure of how the timing of the individual's preferred sleep-wake cycle compares with the average for a population); and changes in the sleep-wake cycle with age, particularly in adolescence and aging, since individuals tend to prefer to go to sleep later during adolescence and earlier in old age. In all circumstances, the evidence that sleep times and architecture are altered and the possible causes of these changes (including altered S, S' and C processes) are examined.