CIRCADIAN PREFERENCE AND COGNITIVE FUNCTIONING AMONG REHABILITATION INPATIENTS

For Whom (and When) the Time Bell Tolls: Chronotypes and the Synchrony Effect

Circadian rhythms are powerful timekeepers that drive physiological and intellectual functioning throughout the day. These rhythms vary across individuals, with morning chronotypes rising and peaking early in the day and evening chronotypes showing a later rise in arousal, with peaks in the afternoon or evening. Chronotype also varies with age from childhood to adolescence to old age. As a result of these differences, the time of day at which people are best at attending, learning, solving analytical problems, making complex decisions, and even behaving ethically varies. Across studies of attention and memory and a range of allied areas, including academic achievement, judgment and decision-making, and neuropsychological assessment, optimal outcomes are found when performance times align with peaks in circadian arousal, a finding known as the synchrony effect. The benefits of performing in synchrony with one's chronotype (and the costs of not doing so) are most robust for individuals with strong morning or evening chronotypes and for tasks that require effortful, analytical processing or the suppression of distracting information. Failure to take the synchrony effect into consideration may be a factor in issues ranging from replication difficulties to school timing to assessing intellectual disabilities and apparent cognitive decline in aging.

Time of Day Effects on Inhibitory Functioning: Cognitive and Neural Evidence of Sundowning in Amnestic Mild Cognitive Impairment

Background: Amnestic mild cognitive impairment (aMCI), a prodromal phase of Alzheimer’s disease (AD), is characterized by episodic memory dysfunction, but inhibitory deficits have also been commonly reported. Time of day (TOD) effects have been confirmed in 1) healthy aging on cognitive processes such as inhibitory control, and 2) on behavior in AD (termed the sundowning effect), but no such research has addressed aMCI. Objective: The present study examined the impact of TOD on the behavioral and electrophysiological correlates of inhibition in 54 individuals with aMCI and 52 healthy controls (HCs), all of morning chronotype. Methods: Participants were randomly assigned to complete two inhibition tasks (Go-NoGo and Flanker) during their optimal (morning) or non-optimal (evening) TOD, while electroencephalography was recorded. Results: Both tasks elicited changes in N2 and P3 event-related potential (ERP) components, which commonly index inhibitory functioning. Analyses showed that the Go-NoGo difference in P3 amplitude was reduced in individuals with aMCI relative to HCs. Compared to HCs, the Flanker difference in P3 amplitude was also reduced and coincided with more errors in the aMCI group. Notably, these behavioral and ERP differences were exaggerated in the non-optimal TOD relative to the optimal TOD. Conclusion: Findings confirm the presence of inhibition deficits in aMCI and provide novel evidence of sundowning effects on inhibitory control in aMCI. Results reinforce the need to consider the influences of TOD in clinical assessments involving individuals with aMCI.

The Effects of Aging and Time of Day on Inhibitory Control: An Event-Related Potential Study

Time of day (TOD) influences on executive functions have been widely reported, with greater efficiency demonstrated at optimal relative to non-optimal TOD according to one’s chronotype (i.e., synchrony effect). Older adults (OAs) show declines in inhibitory control and are more sensitive to the effects of circadian variation on executive functioning. To date, no studies have investigated the effects of TOD and aging on executive functioning using electrophysiological measures. The present study investigated the effects of aging and TOD on the neural correlates of inhibitory processing (N2 and P3) using event-related potentials (ERPs). Go-NoGo and Flanker tasks were administered to 52 OAs of morning chronotype and 51 younger adults (YAs) of afternoon-to-evening chronotype who were randomly assigned to morning or afternoon test sessions, with the optimal TOD for OAs in the morning and for YAs in the afternoon/evening. While behavioral results demonstrated no TOD effects, ERPs indicated synchrony effects. Both YAs and OAs showed greater modulation of Go-NoGo N2 and greater P3 amplitude during the non-optimal than optimal TOD, consistent with the synchrony effect. For the Flanker task, age differences in P3 amplitude were only apparent during the non-optimal TOD. These results suggest that processes associated with inhibitory control are differentially affected by TOD and aging, with age-related reductions in inhibitory efficiency during off-peak test times on measures of interference control. These findings highlight the sensitivity of ERPs to detect TOD effects in the absence of behavioral differences, confirm more pronounced TOD effects in OAs relative to YAs on ERP measures of interference control, and reinforce the need to assess and control for circadian typology in research studies.

Perceived versus objective sleep quality in long-stay hospitalised older adults-a mixed methods study

BACKGROUND

Hospital inpatients experience substantial sleep problems that have been linked with worse health outcomes, poor quality of life and the post-hospital syndrome. However, little is known about assessing sleep issues in older hospitalised patients.

OBJECTIVE

To conduct an in-depth investigation on hospitalised older adults' sleep challenges and methods of sleep assessment.

DESIGN

Cross-sectional observational study.

SETTING

Public hospital inpatient unit.

SUBJECTS

Long-stay hospitalised older adults.

METHODS

Data were collected using validated sleep questionnaires, actigraphy devices and qualitative interviews. Quantitative data were analysed with descriptive statistics, multiple logistic regression and Cohen's Kappa. Qualitative data were analysed with qualitative content analysis; findings compared to the quantitative assessments.

RESULTS

We collected data on 33 older long-stay hospital inpatients, who were mean (SD) 80.2(7.4) years old, 57.6% female and were hospitalised following stroke, medical illness and orthopaedic fracture. Mean (SD) total sleep time and actigraphic sleep efficiency were 480.6(73.6) minutes and 81.5(11.2)%, respectively. About, 57.6% were poor sleepers (Pittsburgh Sleep Quality Index [PSQI]) and 30.8% had indicators of clinical depression/low quality of life (WHO-5 well-being index). Three main themes were identified: "sleep assessment"; "factors that affect sleep"; "expectations of sleep". Bad sleepers were more likely to feel a lack of control over their sleep, while good sleepers spoke about the ability to adjust and accept their circumstances.

CONCLUSIONS

We found high levels of sleep problems and identified substantial discrepancies between the validated sleep questionnaire and qualitative response data. Our findings indicate that standard assessment tools, such as PSQI, may not be suitable to assess sleep in hospitalised older adults and call for further investigations to build more appropriate methods. Further exploring psychological factors and expectations could potentially lead to novel interventions to improve sleep in this setting.

An exploratory investigation of the effect of naturalistic light on depression, anxiety, and cognitive outcomes in stroke patients during admission for rehabilitation: A randomized controlled trial

BACKGROUND

Patients admitted for rehabilitation often lack sufficient natural light to entrain their circadian rhythm.

OBJECTIVE

Installed diurnal naturalistic light may positively influence the outcome of depressive mood, anxiety, and cognition in such patients.

METHODS

A quasi-randomized controlled trial. Ninety stroke patients in need of rehabilitation were randomized between May 1, 2014, and June 1, 2015 to either a rehabilitation unit equipped entirely with always on naturalistic lighting (IU), or to a rehabilitation unit with standard indoor lighting (CU).Examinations were performed at inclusion and discharge. The following changes were investigated: depressive mood based on the Hamilton Depression scale (HAM-D6) and Major Depression Inventory scale (MDI), anxiety based on the Hospital Anxiety and Depression Scale (HADS), cognition based on the Montreal Cognitive Assessment (MoCA) and well-being based on the Well-being Index (WHO-5).

RESULTS

Depressive mood (MDI p = 0.0005, HAM-D6 p = 0.011) and anxiety (HADS anxiety p = 0.045) was reduced, and well-being (WHO-5 p = 0.046) was increased, in the IU at discharge compared to the CU. No difference was found in cognition (MoCA p = 0.969).

CONCLUSIONS

This study is the first to demonstrate that exposure to naturalistic light during admission may significantly improve mental health in rehabilitation patients. Further studies are needed to confirm these findings.

Impact of naturalistic lighting on hospitalized stroke patients in a rehabilitation unit: Design and measurement

INTRODUCTION AND RATIONALE

Stroke is a major cause of acquired cerebral disability among adults, frequently accompanied by depression, anxiety, cognitive impairment, disrupted sleep and fatigue. New ways of intervention to prevent these complications are therefore needed. The major circadian regulator, the suprachiasmatic nucleus, is mainly controlled by natural daylight, and the blue spectrum is considered the most powerful. During stroke rehabilitation, patients typically are mostly indoors and therefore not exposed to the natural daytime variation in light intensity. Furthermore, several rehabilitation hospitals may be exposed to powerful light in the blue spectrum, but at a time that is adversely related to their endogenous circadian phase, for example in the late evening instead of the daytime.

HYPOTHESIS

Naturalistic light that mimics the natural daytime spectrum variation will have a positive impact on the health of poststroke patients admitted to rehabilitation. We test specifically for improved sleep and less fatigue (questionnaires, polysomnography, Actiwatch), improved well-being (questionnaires), lessen anxiety and depression (questionnaires), improved cognition (tests), stabilizing of the autonomous nervous system (ECG/HR, blood pressure, temperature) and stabilizing of the diurnal biochemistry (blood markers).

STUDY DESIGN

The study is a prospective parallel longitudinal randomized controlled study (quasi randomization). Stroke patients in need of rehabilitation will be included at the acute stroke unit and randomized to either the intervention unit (naturalistic lighting) or the control unit (CU) (standard lighting). The naturalistic light is installed in the entire IU (Cromaviso, Denmark).

CONCLUSION

This study aims to elucidate the influence of naturalistic light on patients during long-term hospitalization in a real hospital setting. The hypotheses are based on preclinical research, as studies using naturalistic light have never been performed before. Investigating the effects of naturalistic light in a clinical setting is therefore much needed.

Time-of-day affects prospective memory differently in younger and older adults

The goal of this study was to investigate the impact of circadian arousal on prospective memory performance as a function of age. We tested a younger (18-34 years) and an older group (56-95 years) of participants on- and off-peak with regard to their circadian arousal patterns in a computer-based laboratory experiment. For the prospective memory task, participants had to press a particular key whenever specific target words appeared in an ongoing concreteness-judgment task. The results showed that prospective memory performance was better on- than off-peak in younger but not older participants. Younger participants consistently outperformed older participants in all conditions. We conclude that prospective remembering underlies time-of-day effects which most likely reflect controlled processes.

Time of day affects implicit memory for unattended stimuli

We investigated whether circadian arousal affects perceptual priming as a function of whether stimuli were attended or ignored during learning. We tested 160 participants on- and off-peak with regards to their circadian arousal. In the study phase, they were presented with two superimposed pictures in different colours. They had to name the pictures of one colour while ignoring the others. In the test phase, they were presented with the same and randomly intermixed new pictures. Each picture was presented in black colour in a fragment completion task. Priming was measured as the difference in fragmentation level at which the pictures from the study phase were named compared to the new pictures. Priming was stronger for attended than ignored pictures. Time of day affected priming only for ignored pictures, with stronger priming effects off-peak than on-peak. Thus, circadian arousal seems to favour the encoding of unattended materials specifically at off-peak.

Computer-based tools for assessing micro-longitudinal patterns of cognitive function in older adults

Patterns of cognitive change over micro-longitudinal timescales (i.e., ranging from hours to days) are associated with a wide range of age-related health and functional outcomes. However, practical issues of conducting high-frequency assessments make investigations of micro-longitudinal cognition costly and burdensome to run. One way of addressing this is to develop cognitive assessments that can be performed by older adults, in their own homes, without a researcher being present. Here, we address the question of whether reliable and valid cognitive data can be collected over micro-longitudinal timescales using unsupervised cognitive tests.In study 1, 48 older adults completed two touchscreen cognitive tests, on three occasions, in controlled conditions, alongside a battery of standard tests of cognitive functions. In study 2, 40 older adults completed the same two computerized tasks on multiple occasions, over three separate week-long periods, in their own homes, without a researcher present. Here, the tasks were incorporated into a wider touchscreen system (Novel Assessment of Nutrition and Ageing (NANA)) developed to assess multiple domains of health and behavior. Standard tests of cognitive function were also administered prior to participants using the NANA system.Performance on the two "NANA" cognitive tasks showed convergent validity with, and similar levels of reliability to, the standard cognitive battery in both studies. Completion and accuracy rates were also very high. These results show that reliable and valid cognitive data can be collected from older adults using unsupervised computerized tests, thus affording new opportunities for the investigation of cognitive.

Timing is everything: Age differences in the cognitive control network are modulated by time of day

Behavioral evidence suggests that the attention-based ability to regulate distraction varies across the day in synchrony with a circadian arousal rhythm that changes across the life span. Using functional magnetic resonance imaging (fMRI), we assessed whether neural activity in an attention control network also varies across the day and with behavioral markers. We tested older adults in the morning or afternoon and younger adults tested in the afternoon using a 1-back task with superimposed distractors, followed by an implicit test for the distractors. Behavioral results replicated earlier findings with older adults tested in the morning better able to ignore distraction than those tested in the afternoon. Imaging results showed that time of testing modulates task-related fMRI signals in older adults and that age differences were reduced when older adults are tested at peak times of day. In particular, older adults tested in the morning activated similar cognitive control regions to those activated by young adults (rostral prefrontal and superior parietal cortex), whereas older adults tested in the afternoon were reliably different; furthermore, the degree to which participants were able to activate the control regions listed above correlated with the ability to suppress distracting information.

Cognitive parameters and morning and evening types: two decades of research (1990-2009)

An important area of study has examined cognitive aspects of morningness-eveningness orientation. Optimal times of efficiency in participants classified as Morning and Evening types are of great importance for understanding their cognitive abilities. The present review covers the last two decades (1990-2009), during which the important review by Tankova, Adan, and Buela-Casal appeared, and focuses particularly on attention, memory, and executive functions.

The predictive validity of a brief inpatient neuropsychologic battery for persons with traumatic brain injury

OBJECTIVE

To examine the predictive validity of a brief neuropsychologic test battery consisting of the Galveston Orientation and Amnesia Test, the California Verbal Learning Test-II, Trail-Making Test (TMT), Symbol Digit Modalities Test, grooved pegboard, phonemic and categorical word generation tasks, the Wechsler Test of Adult Reading (WTAR), and the Wisconsin Card Sorting Test-64 relative to functional outcome at 1 year in persons with traumatic brain injury.

DESIGN

Inception cohort study. Follow-up period of 12 months.

SETTING

Seven Traumatic Brain Injury Model System centers. Neuropsychologic testing was conducted during the acute inpatient rehabilitation stay and functional outcome measures were obtained at 1-year outpatient follow-up.

PARTICIPANTS

Adults (N=174) who met criteria for admission to inpatient brain injury rehabilitation.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

FIM instrument, Disability Rating Scale, Supervision Rating Scale, Satisfaction With Life Scale (SWLS), and Glasgow Outcome Scale-Extended.

RESULTS

Multiple regression analyses revealed that performance on the neuropsychologic test battery was predictive of outcome at 1 year postinjury for all outcome measures, except FIM motor scores and the SWLS. Cognitive performance using this battery was found to predict 1-year outcomes above and beyond functional variables and injury severity variables collected during inpatient rehabilitation, thereby indicating incremental validity for this test battery. Individual tests that were found to be significant predictors of 1-year outcomes included the WTAR and TMT part B.

CONCLUSIONS

These findings support the clinical utility and ecological validity of this battery with respect to level of disability, functional independence, and supervision required.

Do cognitively impaired patients benefit from rehabilitation?

Rehabilitation in broad terms is a process aimed at restoring a person's functional capacity particularly in relation to activities of daily living. Studies have shown that hospitalization of older patients is a major risk factor for an often irreversible decline in function, and that functional decline from baseline occurs as early as day two of admission. Rehabilitation is therefore often required for older patients following an admission to an acute hospital. Older patients admitted for rehabilitation are more likely to be functionally impaired and are more medically complex than younger patients.

Cognitive function does not worsen during pegylated interferon and ribavirin retreatment of chronic hepatitis C

Treatment of chronic hepatitis C with pegylated interferon (peginterferon) and ribavirin can cause or exacerbate depression but its effects on cognitive function are largely unknown. The aim of this study was to determine whether treatment with peginterferon and ribavirin adversely impacts cognitive function in patients with chronic hepatitis C. Prior nonresponders to interferon were retreated with peginterferon alfa-2a and ribavirin for 24 (n=177) or 48 weeks (n=57) in the Hepatitis C Antiviral Long-term Treatment Against Cirrhosis trial. Cognitive function was prospectively assessed using a battery of 10 standardized neuropsychological tests at weeks 0, 24, 48, and 72. Cognitive impairment was defined based upon a global deficit score. The Beck Depression Inventory and Brief Symptom Inventory were used to assess mood status. The 57 subjects who completed 48 weeks of antiviral therapy reported significant increases in difficulty concentrating, emotional distress, and symptoms of depression, all of which improved after cessation of therapy [P<0.0001, analysis of variance (ANOVA)]. Nonetheless, the frequency of cognitive impairment did not increase during the first 24 weeks of treatment in 177 patients (34% versus 32%, P=0.64) nor in the 57 patients completing 48 weeks of treatment (P=0.48, ANOVA).

CONCLUSION

Retreatment of prior non-responders with peginterferon and ribavirin was not associated with objective evidence of cognitive impairment as measured by a comprehensive battery of neuropsychological tests. The lack of cognitive impairment is reassuring and suggests that self-reported symptoms of cognitive dysfunction are more likely related to the systemic and psychiatric side effects of antiviral treatment rather than measurable changes in cognition.