Sensitivity to mental effort and test-retest reliability of heart rate variability measures in healthy seniors.

OBJECTIVES: To determine (1) whether heart rate variability (HRV) was a sensitive and reliable measure in mental effort tasks carried out by healthy seniors and (2) whether non-linear approaches to HRV analysis, in addition to traditional time and frequency domain approaches were useful to study such effects. METHODS: Forty healthy seniors performed two visual working memory tasks requiring different levels of mental effort, while ECG was recorded. They underwent the same tasks and recordings 2 weeks later. Traditional and 13 non-linear indices of HRV including Poincaré, entropy and detrended fluctuation analysis (DFA) were determined. RESULTS: Time domain, especially mean R-R interval (RRI), frequency domain and, among non-linear parameters - Poincaré and DFA were the most reliable indices. Mean RRI, time domain and Poincaré were also the most sensitive to different mental effort task loads and had the largest effect size. CONCLUSIONS: Overall, linear measures were the most sensitive and reliable indices to mental effort. In non-linear measures, Poincaré was the most reliable and sensitive, suggesting possible usefulness as an independent marker in cognitive function tasks in healthy seniors. SIGNIFICANCE: A large number of HRV parameters was both reliable as well as sensitive indices of mental effort, although the simple linear methods were the most sensitive.

Assessing sleep architecture in dementia caregivers at home using an ambulatory polysomnographic system.

Findings from previous research assessing sleep quality in caregivers are inconsistent due to differences in sleep assessment methods. This study evaluated sleep in dementia caregivers using a comprehensive sleep assessment utilizing an ambulatory polysomnography (PSG) device. A total of 20 caregivers and 20 noncaregivers rated their perceived sleep quality, stress, and depressive symptoms; provided samples of cortisol and inflammatory biomarkers; and completed an objective sleep assessment using a portable PSG device. Caregivers reported greater perceived stress than noncaregivers. Next, the groups had different sleep architecture: caregivers spent less proportion of their sleep in restorative sleep stages compared to noncaregivers. Further, levels of C-reactive protein and awakening salivary cortisol were greater in caregivers than in noncaregivers, and these measures were related to sleep quality. Our findings indicate that sleep disruption is a significant concomitant of caregiving and may affect caregiver's health. Sleep quality of caregivers might be a useful target for a clinical intervention.

Pilot controlled trial of mindfulness meditation and education for dementia caregivers.

OBJECTIVES: The objectives of this study were to evaluate whether a mindfulness meditation intervention may be effective in caregivers of close relatives with dementia and to help refine the protocol for future larger trials. DESIGN: The design was a pilot randomized trial to evaluate the effectiveness of a mindfulness meditation intervention adapted from the Mindfulness-Based Cognitive Therapy program in relation to two comparison groups: an education class based on Powerful Tools for Caregivers serving as an active control group and a respite-only group serving as a pragmatic control. SETTINGS/LOCATION: This study was conducted at the Oregon Health & Science University, Portland, OR. SUBJECTS: The subjects were community-dwelling caregivers aged 45-85 years of close relatives with dementia. INTERVENTIONS: The two active interventions lasted 7 weeks, and consisted of one 90-minute session per week along with at-home implementation of knowledge learned. The respite-only condition provided the same duration of respite care that was needed for the active interventions. OUTCOME MEASURES: Subjects were assessed prior to randomization and again after completing classes at 8 weeks. The primary outcome measure was a self-rated measure of caregiver stress, the Revised Memory and Behavior Problems Checklist (RMBPC). Secondary outcome measures included mood, fatigue, self-efficacy, mindfulness, salivary cortisols, cytokines, and cognitive function. We also evaluated self-rated stress in the subjects' own environment, expectancy of improvement, and credibility of the interventions. RESULTS: There were 31 caregivers randomized and 28 completers. There was a significant effect on RMBPC by group covarying for baseline RMBPC, with both active interventions showing improvement compared with the respite-only group. Most of the secondary outcome measures were not significantly affected by the interventions. There was an intervention effect on the caregiver self-efficacy measure and on cognitive measures. Although mindfulness was not impacted by the intervention, there were significant correlations between mindfulness and self-rated mood and stress scores. CONCLUSIONS: Both mindfulness and education interventions decreased the self-rated caregiver stress compared to the respite-only control.

Salivary cortisol awakening response in mild Alzheimer disease, caregivers, and noncaregivers.

Alterations in the hypothalamic-pituitary-adrenal axis have been noted in people with Alzheimer disease (AD) and in the people caring for them. In a case-control study, we assessed whether the cortisol response at awakening and diurnal cortisol would reflect these changes. AD patients, their caregivers, and healthy senior noncaregivers collected saliva within 5 minutes of waking, 30 minutes after waking, before lunch, 1 hour after lunch, and at 11 pm or when getting ready for bed. They also completed a Perceived Stress Scale. Total cortisol for the day after adjusting for antidepressant use revealed a group effect [F(2,39)=12.49, P<0.0001], with mild AD patients and caregivers having higher cortisol values. Unlike the noncaregivers (t=-1.15, df=14, P>0.27), both cortisol values of the AD caregivers (t=-2.96, df=16, P<0.03) and the AD patients' (t=-2.5, df=14, P<0.01) increased between awakening and 30 minutes afterward. There were also group differences at awakening [F(2,48)=4.6, P=0.012] adjusting for antidepressant use and 30 minutes after waking adjusting for antidepressant use and awakening cortisol [F(2,46)=4.7, P=0.014<0.02). AD patients (r=0.45, P=0.08) and caregivers (r=0.44, P=0.10) with higher cortisol values 30 minutes after waking also showed a trend toward higher perceived stress scores. Salivary cortisol and cortisol response on awakening may enhance future studies relating free cortisol to subjective psychologic and physiologic markers.

Expectancy effect: impact of pill administration on cognitive performance in healthy seniors.

Expectancy or placebo effects on cognitive function have not been well studied. To determine the effect of taking pills on cognitive function, 40 participants were randomly assigned to a pill or no-pill condition. Healthy seniors who took a 2-week supply of methylcellulose pills, which they were told was an experimental cognitive enhancer, were compared to seniors not taking any pills. There were 2 primary outcome measures defined prior to the study-Consortium to Establish a Registry for Alzheimer's Disease (CERAD) Word List delayed recall and Stroop color word task time-as well as 7 other cognitive outcome measures. There was a significant effect of pill taking on the 2 primary outcome measures. There was also an effect of pill taking on choice reaction time and Word List immediate recall but not on the other 5 secondary cognitive outcome measures. In an exploratory analysis of potential predictors of the expectancy effect, perceived stress and self-efficacy but not personality traits interacted with the pill-taking effect on cognitive function. Further characterizing and understanding this observed expectancy effect is important to maximize cognitive health and improve clinical trial design.

Second generation complementary and alternative medicine physiologic data collection and monitoring research platform.

Progress on our second generation portable system specifically designed to collect 24 hour ambulatory physiologic data from human subjects is reported. The upgraded system has more sensor flexibility and better performance and is smaller, lighter, and simpler to use than our previous version. The new system continues to support a wide variety of sensors found useful for complementary and alternative medicine (CAM) research and has been designed using a modular approach for future expansion of capabilities. The system has improved data storage and supports popular physiologic data formats. Support for wireless control and real-time data monitoring has been added which demonstrates capabilities to be used for physiologic feedback control. The system was designed specifically to support the needs of investigators studying CAM mind-body interventions but could be used for a variety of research needs.

Cognition and fatigue in multiple sclerosis: Potential effects of medications with central nervous system activity.

To evaluate the potential effects of medications with central nervous system (CNS) activity on cognitive function and fatigue in multiple sclerosis (MS), we performed a retrospective analysis of medication use among 70 subjects with MS who were participating in a clinical trial for evaluation of the effects of yoga and exercise programs on cognition and fatigue. Among these MS subjects, 74% were taking at least one potentially CNS-active medication. These 70 subjects were divided into two groups: those taking at least one CNS-active medication (n = 52) and those not on any medications with potential CNS activity (n = 18). We compared assessments of cognitive function and fatigue using an analysis of covariance. MS subjects on CNS-active medication had greater impairment on measures of processing speed, sustained attention, and fatigue than those not on these medications. While these findings do not establish a causal relationship between medication use and cognitive impairment and fatigue, the data indicate that researchers need to control for use of CNS-active medications when conducting studies of cognitive impairment and fatigue in MS subjects.

Randomized, controlled, six-month trial of yoga in healthy seniors: effects on cognition and quality of life.

CONTEXT: There are potential benefits of mind-body techniques on cognitive function because the techniques involve an active attentional or mindfulness component, but this has not been fully explored. OBJECTIVE: To determine the effect of yoga on cognitive function, fatigue, mood, and quality of life in seniors. DESIGN: Randomized, controlled trial comparing yoga, exercise, and wait-list control groups. PARTICIPANTS: One hundred thirty-five generally healthy men and women aged 65-85 years. INTERVENTION: Participants were randomized to 6 months of Hatha yoga class, walking exercise class, or wait-list control. Subjects assigned to classes also were asked to practice at home. MAIN OUTCOME MEASURES: Outcome assessments performed at baseline and after the 6-month period included a battery of cognitive measures focused on attention and alertness, the primary outcome measures being performance on the Stroop Test and a quantitative electroencephalogram (EEG) measure of alertness; SF-36 health-related quality of life; Profile of Mood States; Multi-Dimensional Fatigue Inventory; and physical measures related to the interventions. RESULTS: One hundred thirty-five subjects were recruited and randomized. Seventeen subjects did not finish the 6-month intervention. There were no effects from either of the active interventions on any of the cognitive and alertness outcome measures. The yoga intervention produced improvements in physical measures (eg, timed 1-legged standing, forward flexibility) as well as a number of quality-of-life measures related to sense of well-being and energy and fatigue compared to controls. CONCLUSIONS: There were no relative improvements of cognitive function among healthy seniors in the yoga or exercise group compared to the wait-list control group. Those in the yoga group showed significant improvement in quality-of-life and physical measures compared to exercise and wait-list control groups.

24 hour ambulatory research system supporting multiple physiologic sensors.

The design and development of a 24-hour ambulatory physiological data collection system is reported. The system was designed specifically to support the needs of investigators studying mind-body interventions but could be used for a variety of research needs. The system is novel in that it supports a wide variety of physiologic sensors with a relatively high sample rate, full data storage, and standalone run-time of greater than 24 hours. Experience with data acquisition and methods for post-acquisition data analysis are also discussed.

Patterns of dietary supplement usage in demographically diverse older people.

OBJECTIVE: To analyze dietary supplement usage data from 494 older adults, aged 65 to 101 years. SETTING: Community dwellers living independently of institutionalized care. DESIGN: All dietary supplements, including botanicals, were recorded to aid in assessing the health status of older adults. PARTICIPANTS: 1) 224 individuals enrolled in a study that follows the health of persons 85 years and older (oldest-old) in Klamath County, a non-metropolitan area in southern Oregon; 2) 134 participants of oldest-old age living in the metropolitan Portland area, enrolled in a randomized clinical trial of GBE biloba extract (GBE) for dementia prevention; and 3) 136 participants, ages 65-85 years (young-old), also of the Portland area, enrolled in a study of the effects of yoga and exercise on cognition. MEASUREMENTS: Data verified from labels, not from self-report. RESULTS: Of the participants, 70.6% used dietary supplements. Women took supplements more often than men, and usage decreased with age. A greater percentage, 67.4%, of the non-metropolitan oldest-old took supplements, compared to 56.7% of the metropolitan oldest-old. The greatest usage, 89.7%, was in the metropolitan young-olds. All of these percentages exceed those for comparable age groups in national representative surveys. CONCLUSIONS: Dietary supplement usage by older adults in these studies in Oregon exceeded that in other reports and may reflect high interest in complementary and alternative medicine. This report confirms the results of other studies showing that elderly adults, particularly women, use dietary supplements more than other segments of the US population. Researchers and clinicians should be aware of this pattern and potential conflicts with research design or treatment regimen intended for older people.

Heart rate variability analysis of effect of nicotine using periodograms.

Heart rate variability (HRV) is frequently used to measure autonomic nervous system (ANS) activity. However, little is known about the mechanism underlying pharmacologically induced changes in HRV. Previous research has shown that nicotine exposure stimulates the ANS, mediating a wide spectrum of physiological and behavioral effects, including altered respiratory sinus arrhythmia and enhanced arousal and attention. Using Lomb-Welch periodograms, the effect of nicotine on the ANS in 14 nicotine-naive human subjects are studied. Results showed an increase in the low frequency (LF) to high frequency (HF) ratio with little change in mean heart rate. Results suggest that nicotine affects both sympathetic and parasympathetic reactivities and that the LF/HF best characterizes early ANS activated nicotine changes in HRV. The Lomb-Welch periodogram of the HRV is also compared to the conventional interpolated Welch periodogram. The attenuation of the high frequency components due to interpolation of the non-uniform R-R intervals is found to be a function of the power of the high frequency components, increasing with increasing power. Thus analyses using Welch periodograms that make use of the high frequency components may yield erroneous results.

Nicotine effects on alertness and spatial attention in non-smokers.

Nicotine reportedly improves covert orienting of spatial attention, but enhanced alertness may also play a role. The present study explored nicotine effects on measures of spatial attention and alertness in non-smokers. Nicotine was delivered to 17 non-smokers (data from 12 subjects were analyzed) by a 7-mg transdermal patch (one patch in a low-nicotine condition; two patches in a high-nicotine condition). We examined nicotine's effects on spatial attention using a covert orienting task with central, predictive cue stimuli. Nicotine effects on alertness were examined with EEG and subjective questionnaires. Blood was drawn and serum levels of nicotine are reported. Nicotine decreased overall reaction times in the covert orienting task. There was no change in the validity effect, the reaction time difference between validly and invalidly cued targets. However, nicotine significantly improved both EEG and self-rated measures of alertness. We conclude that nicotine increases alertness in non-smokers, but we found no improvement in spatial attention using a covert orienting task.