Circadian rhythms and psychiatric disorders in the elderly

The Association between Circadian Syndrome and Frailty in US adults: a cross-sectional study of NHANES Data from 2007 to 2018

PURPOSE

Frailty and Circadian Syndrome (CircS) are prevalent among the elderly, yet the link between them remains underexplored. This study aims to examine the association between CircS and frailty, particularly focusing on the impact of various CircS components on frailty.

MATERIALS AND METHODS

We conducted a cross-sectional analysis using data from the National Health and Nutrition Examination Survey (NHANES) spanning 2007 to 2018. The 49-item Frailty Index (FI) was employed to assess frailty. To understand the prevalence of CircS in relation to frailty, we applied three multivariate logistic regression models. Additionally, subgroup and interaction analyses were performed to investigate potential modifying factors.

RESULTS

The study included 8,569 participants. In fully adjusted models, individuals with CircS showed a significantly higher risk of frailty compared to those without CircS (Odds Ratio [OR] = 2.18, 95% Confidence Interval [CI]: 1.91-2.49, p < 0.001). A trend of increasing frailty risk with greater CircS component was observed (trend test p < 0.001). Age (p = 0.01) and race (p = 0.02) interactions notably influenced this association, although the direction of effect was consistent across subgroups. Sensitivity analysis further confirmed the strength of this relationship.

CONCLUSION

This study identifies a strong positive correlation between CircS and frailty in the elderly. The risk of frailty escalates with an increasing number of CircS components. These findings highlight the intricate interplay between circadian syndrome and frailty in older adults, offering valuable insights for developing targeted prevention and intervention strategies.

Circadian depression: A mood disorder phenotype

Major mood syndromes are among the most common and disabling mental disorders. However, a lack of clear delineation of their underlying pathophysiological mechanisms is a major barrier to prevention and optimised treatments. Dysfunction of the 24-h circadian system is a candidate mechanism that has genetic, behavioural, and neurobiological links to mood syndromes. Here, we outline evidence for a new clinical phenotype, which we have called 'circadian depression'. We propose that key clinical characteristics of circadian depression include disrupted 24-h sleep-wake cycles, reduced motor activity, low subjective energy, and weight gain. The illness course includes early age-of-onset, phenomena suggestive of bipolarity (defined by bidirectional associations between objective motor and subjective energy/mood states), poor response to conventional antidepressant medications, and concurrent cardiometabolic and inflammatory disturbances. Identifying this phenotype could be clinically valuable, as circadian-targeted strategies show promise for reducing depressive symptoms and stabilising illness course. Further investigation of underlying circadian disturbances in mood syndromes is needed to evaluate the clinical utility of this phenotype and guide the optimal use of circadian-targeted interventions.

Sleep in older adults and in subjects with dementia

The neuronal structures for the regulation of sleep and wakefulness are located in the brain. This complex network is vulnerable to numerous factors, most importantly neurodegenerative diseases and drugs. The macrostructure and microstructure of sleep change with age. These changes are more pronounced in subjects with dementia. Sleep disorders in subjects with dementia may be independent of dementia or caused by dementia. Furthermore, epidemiological studies reveal that sleep disorders per se may induce dementia by reduction of cerebral clearance of beta-amyloids. The population attributable risk (PAR) of sleep disturbances to the incidence of dementia is estimated to be about 15%; therefore, management of sleep disturbances in older adults and subjects with dementia gives the opportunity of an impact on incidence and course of dementia. Sleep history should be taken from each individual and obvious sleep disturbances, especially sleep apnea, should be managed according to current guidelines. Future studies that concern the incidence and the management of dementia must take into account sleep and sleep disturbances.

Serum Levels of Albumin-β-Amyloid Complex in Patients with Depression

OBJECTIVE

Epidemiologic studies have demonstrated that suffering from depression may be a risk for Alzheimer disease (AD). As a possible biologic mechanism underlying the transition from depression to AD, it has been speculated that pathologic changes in β-amyloid (Aβ) metabolism are involved. To further understand the peripheral kinetics of amyloid in patients with depression, we investigated serum levels of free Aβ and albumin-bound Aβ.

METHODS

Seventy inpatients with DSM-IV major depressive disorder (MDD) and 81 healthy individuals (the comparison group) were recruited between June 2012 and February 2014. Serum Aβ40 and Aβ42 levels, Aβ40/Aβ42 ratio, and serum levels of albumin-Aβ complexes (SLAACs) were compared between the comparison group and patients in two age groups comprising younger (<60 years) and elderly (≥60 years) people.

RESULTS

SLAAC was decreased in older patients with MDD but not in younger patients. The serum-free Aβ40/Aβ42 ratio was higher in patients with depression, even in younger patients.

CONCLUSION

Our findings suggest that free Aβ and the albumin-bound Aβ reflect a different serum amyloid kinetics in depression. We speculate that serum-free Aβ reflects changes in amyloid metabolism in patients suffering from depression and albumin-bound Aβ reflects AD pathology and may be a potential predictor of the prodromal stage of AD.

Soluble amyloid-β levels and late-life depression

Late-Life Major Depression (LLMD) is a complex heterogeneous disorder that has multiple pathophysiological mechanisms such as medical comorbidity, vascular-related factors and Alzheimer's disease (AD). There is an association between LLMD and AD, with LLMD possibly being a risk factor for, or early symptom of AD and vascular dementia. Whether depression is an etiologic risk factor for dementia, or part of the dementia prodrome remains controversial. AD has a long prodromal period with the neuropathologic features of the disease preceding the onset of clinical symptoms by as much as 15-20 years. Clinicopathological studies have provided robust support for the importance of Aβ42 in the pathogenesis of AD, but several other risk factors have also been identified. Given the relationship between Aβ42 and AD, a potential relationship between Aβ42 and LLMD would improve the understanding of the association between LLMD and AD. We reviewed 15 studies that analyzed the relationship between soluble Aβ42 and LLMD. For studies looking at plasma and/or cerebrospinal fluid (CSF) levels of Aβ42, the relationship between LLMD and soluble Aβ42 was equivocal, with some studies finding elevated Aβ42 levels associated with LLMD and others finding the opposite, decreased levels of Aβ42 associated with LLMD. It may be that there is poor reliability in the diagnosis of depression in late life, or variability in the criteria and the scales used, or subtypes of depression in late life such as early vs. late onset depression, vascular-related depression, and preclinical/comorbid depression in AD. The different correlations associated with each of these factors would be causing the inconsistent results for soluble Aβ42 levels in LLMD, but it is also possible that these patterns derive from disease stage-dependent differences in the trajectory of CSF Aβ42 during older age, or changes in neuronal activity or the sleep/wake cycle produced by LLMD that influence Aβ42 dynamics.

Multi-target strategies for the improved treatment of depressive states: Conceptual foundations and neuronal substrates, drug discovery and therapeutic application

Major depression is a debilitating and recurrent disorder with a substantial lifetime risk and a high social cost. Depressed patients generally display co-morbid symptoms, and depression frequently accompanies other serious disorders. Currently available drugs display limited efficacy and a pronounced delay to onset of action, and all provoke distressing side effects. Cloning of the human genome has fuelled expectations that symptomatic treatment may soon become more rapid and effective, and that depressive states may ultimately be "prevented" or "cured". In pursuing these objectives, in particular for genome-derived, non-monoaminergic targets, "specificity" of drug actions is often emphasized. That is, priority is afforded to agents that interact exclusively with a single site hypothesized as critically involved in the pathogenesis and/or control of depression. Certain highly selective drugs may prove effective, and they remain indispensable in the experimental (and clinical) evaluation of the significance of novel mechanisms. However, by analogy to other multifactorial disorders, "multi-target" agents may be better adapted to the improved treatment of depressive states. Support for this contention is garnered from a broad palette of observations, ranging from mechanisms of action of adjunctive drug combinations and electroconvulsive therapy to "network theory" analysis of the etiology and management of depressive states. The review also outlines opportunities to be exploited, and challenges to be addressed, in the discovery and characterization of drugs recognizing multiple targets. Finally, a diversity of multi-target strategies is proposed for the more efficacious and rapid control of core and co-morbid symptoms of depression, together with improved tolerance relative to currently available agents.

Demographic and sleep characteristics in cognitively impaired nursing home residents with and without severe sleep/wake pattern inefficiency

This study determined the differences in demographic and sleep characteristics in cognitively impaired nursing home residents with and without severe sleep/wake pattern inefficiency. Identification of characteristics associated with severe sleep/wake pattern inefficiency will allow health care providers to make the best cost effective use of finite resources because they can target interventions towards those most likely to need them. This article reports the baseline characteristics of the total sample, compares the demographic and sleep characteristics of the subgroups with and without severe sleep/wake pattern inefficiency, and reviews related literature.

The effects of bright-light therapy on actigraphical measured sleep last for several weeks post-treatment. A study in a nursing home population

We investigated the time-course of nocturnal actigraphic measures, following the termination of bright-light therapy for sleep disturbances in demented nursing home patients. From an earlier study, 11 nursing home patients (86 +/- 9 years, Mini-Mental Status Examination score 12 +/- 4) with actigraphically measured sleep efficiency < 85%, were recruited to morning bright-light treatment (6000-8000 lux) 2 h per day for 14 days. Actigraphic measures were registered at pretreatment, treatment and at four monthly post-treatment periods. Each actigraphic recording period consisted of seven consecutive days. Sleep improved substantially with treatment; sleep efficiency increased from 73% to 86% and total nocturnal wake time was reduced by nearly 2 h. During the 16 weeks post-treatment period, actigraphic measures gradually returned to pretreatment levels. Sleep efficiency remained significantly higher than the pretreatment level 4 weeks after treatment termination. Sleep onset latency remained significantly reduced up until 12 weeks post-treatment. This study supports previous findings of beneficial effects of bright-light therapy for sleep disturbances in demented nursing home patients. Furthermore, these results are the first to suggest that post-treatment effects of short-term bright-light therapy may last longer than previously assumed.

Identification of human Clock gene variants by denaturing high-performance liquid chromatography

The human Clock gene ( hClock) encodes the CLOCK protein essential for the function of the circadian system. We have screened the entire coding region, including the 5' and 3' untranslated regions (UTRs) and the flanking intronic regions, of the hClock gene for sequence variations in 70 unrelated Chinese Singaporeans with denaturing high-performance liquid chromatography (dHPLC). A total of 15 sequence variations were detected, five of which were novel. All involved single base changes. There were 12 substitutions and three insertions/deletions. All except one were found in the introns or the UTRs. Frequencies of the minor allele for all 15 polymorphisms ranged from 0.7% to almost 50%. For the eight sites whose minor allele frequency was found to be at least 10%, pair-wise comparisons revealed that all except one were in almost complete linkage disequilibrium. Our identification of additional single nucleotide polymorphisms in the hClock gene would provide markers whose frequencies could be established in the selected population and used for further analysis of the phenotypic effects. Our results would also be useful for better planning in the selection of polymorphisms for future genetic association studies involving the hClock gene.

Senescence, sleep, and circadian rhythms

The goal of this review article is to summarize our knowledge and understanding of the overlapping (interdisciplinary) areas of senescence, sleep, and circadian rhythms. Our overview comprehensively (and visually wherever possible), emphasizes the organizational, dynamic, and plastic nature of both sleep and circadian timing system (CTS) during senescent processes in animals and in humans. In this review, we focus on the studies that deal with sleep and circadian rhythms in aged animals and how these studies have closely correlated to and advanced our understanding of similar processes in ageing humans. Our comprehensive summary of various aspects of the existing research on animal and human ageing, both normal and pathological, presented in this review underscores the invaluable advantage of close collaboration between clinicians and basic research scientists and the future challenges inherent in this collaboration. First, our review addresses the common age-related changes that occur in sleep and temporal organization of both animals and humans. Second, we examine the specific modifications that often accompany sleep and CTS during aging. Third, we discuss the clinical epidemiology of sleep dysfunctions during ageing and their current clinical management, both pharmacological and non-pharmacological. Finally, we predict the possible future promises for complementary and alternative medicine (CAM) that pave the way to the emergence of a "Holistic Sleep Medicine" approach to the treatment of sleep disorders in the ageing population. Further studies will provide additional valuable insights into the understanding of both sleep and circadian rhythms during senescence.

Melatonin for treatment of sundowning in elderly persons with dementia - a preliminary study

This pilot study investigated the impact of melatonin administration as a clinical intervention for improving sleep and alleviating sundowning in 11 elderly nursing home residents who suffer from dementia. Melatonin is a hormone produced and secreted by the pineal gland in response to darkness, which plays a major role in the induction and regulation of sleep. Melatonin production decreases with age. Age-related sleep disorders are frequently associated with disruption of circadian cycle rhythms, and sometimes with 'sundowning'. Sundowning refers to the manifestation of agitation and/or confusion in the evening hours. Agitation has been linked to sleep disorders. Analysis revealed a significant decrease in agitated behaviors in all three shifts, and a significant decrease in daytime sleepiness. There was a nonsignificant decrease in latency (time to fall asleep) during the evening shift and no significant changes were reported in night-time sleep ratings. The results of this study are important, because finding ways of decreasing sundowning in elderly persons may improve their well being, alleviate the burden of the caregivers, and even enable caregiving in a less restrictive environment.