Serotonin transporter polymorphism, depressive symptoms, and emotional impulsivity among advanced breast cancer patients

PURPOSE

This study tested a theory linking a marker of low serotonergic function to both depression and impulsivity in a sample of advanced breast cancer patients, among whom elevated depressive symptoms and difficulty regulating emotions are commonly reported.

METHODS

A total of 95 patients provided blood samples for serotonin transporter polymorphic region of the gene (5-HTTLPR) and completed questionnaires that measured depressive symptoms and emotional impulsivity.

RESULTS

Structural equation modeling revealed that the s allele of 5-HTTLPR was related to greater depressive symptoms (β = .20, p < .042) but only marginally to greater emotional impulsivity (β = .19, p < .068). Depressive symptoms and emotional impulsivity were positively related (β = .33, p < .003). Further tests explored possible mediation from genotype to one psychological variable via the other. Results suggest that depressive symptoms, particularly perceived interpersonal rejection, may be a pathway linking genotype to emotional impulsivity.

CONCLUSIONS

Findings provide the first evidence that low serotonergic function contributes to both depression and impulsivity within a clinically meaningful sample. Furthermore, the link of s allele of 5-HTTLPR to emotional impulsivity was mediated by depressive symptoms, particularly perceptions of social rejection. Findings have implications for advanced breast cancer patients' treatment decision.

Eating Decisions Based on Alertness Levels After a Single Night of Sleep Manipulation: A Randomized Clinical Trial

Study Objectives

To determine the relationship between an ecologically-relevant change in sleep behavior and its subsequent effects on daytime alertness and feeding behavior.

Methods

Fifty healthy, young participants (10 male, 40 female) completed two 3-hour study sessions that were at least five days apart. The first session was a baseline evaluation. On the night prior to Session 2, the amount of time in bed was manipulated to be 60%-130% of the individual's habitual sleep time. Within both sessions, subjective (Stanford Sleepiness Scale) and objective (Psychomotor Vigilance Test) alertness were measured. During the middle of each session, a 40-minute ad libitum meal opportunity allowed participants to eat from eight different food items. Food healthfulness, caloric density, distribution, and number of calories were measured and compared to alertness levels.

Results

The induced variation in time in bed resulted in induced variation in both subjective and objective (p < .05) measures of alertness. Decreased subjective alertness was associated with increased total caloric consumption (p < .05), and a greater number of calories consumed from less healthy food (p < .05), as rated by both the investigators and by the participant. Decreased objective alertness was associated with less healthy food choices (p < .05), and the consumption of more food from the calorically-dense items (p < .05).

Conclusions

Ecologically-relevant impairments in subjective and objective alertness are associated with increased caloric intake and dysfunctional eating decisions. People experiencing reduced alertness after modest sleep loss may be more willing to eat food they recognize as less healthful, and appear to prefer more calorically-dense foods.

Correlates of sleep quality in midlife and beyond: a machine learning analysis

OBJECTIVES

In older adults, traditional metrics derived from polysomnography (PSG) are not well correlated with subjective sleep quality. Little is known about whether the association between PSG and subjective sleep quality changes with age, or whether quantitative electroencephalography (qEEG) is associated with sleep quality. Therefore, we examined the relationship between subjective sleep quality and objective sleep characteristics (standard PSG and qEEG) across middle to older adulthood.

METHODS

Using cross-sectional analyses of 3173 community-dwelling men and women aged between 39 and 90 participating in the Sleep Heart Health Study, we examined the relationship between a morning rating of the prior night's sleep quality (sleep depth and restfulness) and polysomnographic, and qEEG descriptors of that single night of sleep, along with clinical and demographic measures. Multivariable models were constructed using two machine learning methods, namely lasso penalized regressions and random forests.

RESULTS

Little variance was explained across models. Greater objective sleep efficiency, reduced wake after sleep onset, and fewer sleep-to-wake stage transitions were each associated with higher sleep quality; qEEG variables contributed little explanatory power. The oldest adults reported the highest sleep quality even as objective sleep deteriorated such that they would rate their sleep better, given the same level of sleep efficiency. Despite this, there were no major differences in the predictors of subjective sleep across the age span.

CONCLUSION

Standard metrics derived from PSG, including qEEG, contribute little to explaining subjective sleep quality in middle-aged to older adults. The objective correlates of subjective sleep quality do not appear to systematically change with age despite a change in the relationship between subjective sleep quality and objective sleep efficiency.

When a gold standard isn't so golden: Lack of prediction of subjective sleep quality from sleep polysomnography

BACKGROUND

Reports of subjective sleep quality are frequently collected in research and clinical practice. It is unclear, however, how well polysomnographic measures of sleep correlate with subjective reports of prior-night sleep quality in elderly men and women. Furthermore, the relative importance of various polysomnographic, demographic and clinical characteristics in predicting subjective sleep quality is not known. We sought to determine the correlates of subjective sleep quality in older adults using more recently developed machine learning algorithms that are suitable for selecting and ranking important variables.

METHODS

Community-dwelling older men (n=1024) and women (n=459), a subset of those participating in the Osteoporotic Fractures in Men study and the Study of Osteoporotic Fractures study, respectively, completed a single night of at-home polysomnographic recording of sleep followed by a set of morning questions concerning the prior night's sleep quality. Questionnaires concerning demographics and psychological characteristics were also collected prior to the overnight recording and entered into multivariable models. Two machine learning algorithms, lasso penalized regression and random forests, determined variable selection and the ordering of variable importance separately for men and women.

RESULTS

Thirty-eight sleep, demographic and clinical correlates of sleep quality were considered. Together, these multivariable models explained only 11-17% of the variance in predicting subjective sleep quality. Objective sleep efficiency emerged as the strongest correlate of subjective sleep quality across all models, and across both sexes. Greater total sleep time and sleep stage transitions were also significant objective correlates of subjective sleep quality. The amount of slow wave sleep obtained was not determined to be important.

CONCLUSIONS

Overall, the commonly obtained measures of polysomnographically-defined sleep contributed little to subjective ratings of prior-night sleep quality. Though they explained relatively little of the variance, sleep efficiency, total sleep time and sleep stage transitions were among the most important objective correlates.

Sleep Disturbance, Diabetes, and Cardiovascular Disease in Postmenopausal Veteran Women

PURPOSE OF THE STUDY

To compare the prevalence and cardiometabolic health impact of sleep disturbance among postmenopausal Veteran and non-Veteran participants in the Women's Health Initiative (WHI).

DESIGN AND METHODS

The prevalence of five categories of sleep disturbance--medication/alcohol use for sleep; risk for insomnia; risk for sleep disordered breathing [SDB]; risk for comorbid insomnia and SDB (insomnia + SDB); and aberrant sleep duration [SLD]--was compared in 3,707 Veterans and 141,354 non-Veterans using logistic or multinomial regression. Cox proportional hazards models were used to evaluate the association of sleep disturbance and incident cardiovascular disease (CVD) and Type 2 diabetes in Veterans and non-Veterans.

RESULTS

Women Veterans were more likely to have high risk for insomnia + SDB relative to non-Veteran participants. However, prevalence of other forms of sleep disturbance was similar across groups. Baseline sleep disturbance was not differentially associated with cardiometabolic health outcomes in Veteran versus non-Veteran women. Risks for SDB and insomnia + SDB were both linked to heightened risk of CVD and diabetes; SLD was consistently linked with greater risk of CVD and diabetes in non-Veterans but less strongly and consistently in Veterans.

IMPLICATIONS

Efforts to identify and treat sleep disturbances in postmenopausal women are needed and may positively contribute to the attenuation of cardiometabolic morbidity risk. Increased awareness of women Veterans' vulnerability to postmenopausal insomnia + SDB may be particularly important for health care providers who treat this population.

Standing Balance and Spatiotemporal Aspects of Gait Are Impaired Upon Nocturnal Awakening in Healthy Late Middle-Aged and Older Adults

STUDY OBJECTIVES

Nocturnal awakenings may constitute a unique risk for falls among older adults. We describe differences in gait and balance between presleep and midsleep testing, and whether changes in the lighting environment during the midsleep testing further affect gait and balance.

METHODS

Twenty-one healthy, late middle-aged and older (64.7 ± 8.0 y) adults participated in this repeated-measures design consisting of four overnight laboratory stays. Each night, participants completed baseline visual acuity, gait, and balance testing. After a 2-h sleep opportunity, they were awakened for 13 min into one of four lighting conditions: very dim white light (< 0.5 lux); dim white light (∼28.0 lux); dim orange light (∼28.0 lux); and white room-level light (∼200 lux). During this awakening, participants completed the same sequence of testing as at baseline.

RESULTS

Low-contrast visual acuity significantly decreased with decreasing illuminance conditions (F(3,45) = 98.26, p < 0.001). Our a priori hypothesis was confirmed in that variation in stride velocity and center of pressure path length were significantly worse during the mid-sleep awakening compared to presleep baseline. Lighting conditions during the awakening, however, did not influence these parameters. In exploratory analyses, we found that over one-third of the tested gait and balance parameters were significantly worse at the midsleep awakening as compared to baseline (p < 0.05), and nearly one-quarter had medium to large effect sizes (Cohen d ≥ 0.5; r ≥ 0.3).

CONCLUSIONS

Balance and gait are impaired during midsleep awakenings among healthy, late middle-aged and older adults. This impairment is not ameliorated by exposure to room lighting, when compared to dim lights.

Aberrant nocturnal cortisol and disease progression in women with breast cancer

While a relationship between disruption of circadian rhythms and the progression of cancer has been hypothesized in field and epidemiologic studies, it has never been unequivocally demonstrated. We determined the circadian rhythm of cortisol and sleep in women with advanced breast cancer (ABC) under the conditions necessary to allow for the precise measurement of these variables. Women with ABC (n = 97) and age-matched controls (n = 24) took part in a 24-h intensive physiological monitoring study involving polysomnographic sleep measures and high-density plasma sampling. Sleep was scored using both standard clinical metrics and power spectral analysis. Three-harmonic regression analysis and functional data analysis were used to assess the 24-h and sleep-associated patterns of plasma cortisol, respectively. The circadian pattern of plasma cortisol as described by its timing, timing relative to sleep, or amplitude was indistinguishable between women with ABC and age-matched controls (p's > 0.11, t-tests). There was, however, an aberrant spike of cortisol during the sleep of a subset of women, during which there was an eightfold increase in the amount of objectively measured wake time (p < 0.004, Wilcoxon Signed-Rank). This cortisol aberration was associated with cancer progression such that the larger the aberration, the shorter the disease-free interval (time from initial diagnosis to metastasis; r = -0.30, p = 0.004; linear regression). The same aberrant spike was present in a similar percent of women without ABC and associated with concomitant sleep disruption. A greater understanding of this sleep-related cortisol abnormality, possibly a vulnerability trait, is likely important in our understanding of individual variation in the progression of cancer.

Temporal integration of light flashes by the human circadian system

BACKGROUND

Beyond image formation, the light that is detected by retinal photoreceptors influences subcortical functions, including circadian timing, sleep, and arousal. The physiology of nonimage-forming (NIF) photoresponses in humans is not well understood; therefore, the development of therapeutic interventions based on this physiology, such as bright light therapy to treat chronobiological disorders, remains challenging.

METHODS

Thirty-nine participants were exposed to 60 minutes of either continuous light (n = 8) or sequences of 2-millisecond light flashes (n = 31) with different interstimulus intervals (ISIs; ranging from 2.5 to 240 seconds). Melatonin phase shift and suppression, along with changes in alertness and sleepiness, were assessed.

RESULTS

We determined that the human circadian system integrates flash sequences in a nonlinear fashion with a linear rise to a peak response (ISI = 7.6 ± 0.53 seconds) and a power function decrease following the peak of responsivity. At peak ISI, flashes were at least 2-fold more effective in phase delaying the circadian system as compared with exposure to equiluminous continuous light 3,800 times the duration. Flashes did not change melatonin concentrations or alertness in an ISI-dependent manner.

CONCLUSION

We have demonstrated that intermittent light is more effective than continuous light at eliciting circadian changes. These findings cast light on the phenomenology of photic integration and suggest a dichotomous retinohypothalamic network leading to circadian phase shifting and other NIF photoresponses. Further clinical trials are required to judge the practicality of light flash protocols.

TRIAL REGISTRATION

Clinicaltrials.gov NCT01119365.

FUNDING

National Heart, Lung, and Blood Institute (1R01HL108441-01A1) and Department of Veterans Affairs Sierra Pacific Mental Illness Research, Education, and Clinical Center.

Ubiquity of Undiagnosed Sleep Disordered Breathing in Community-Dwelling Older Male Veterans

OBJECTIVE

To determine the point prevalence of sleep disordered breathing (SDB) in a community-based sample of older male veterans and to determine if common markers of SDB apply to this population.

METHODS

Two hundred fourteen older male Veterans (age 55-89 years) were recruited for a study on post-traumatic stress disorder and cognitive decline. Questionnaires concerning anthropomorphic and psychological variables were obtained, as was an overnight polysomnographic examination of sleep.

RESULTS

Only 13% of the participants lacked clinically meaningful SDB, whereas 33% had moderate SDB and 54% had severe SDB. Being overweight, self-reported snoring, and excessive daytime sleepiness all had good sensitivity (0.86-0.92) but very poor specificity (0.10-0.28) for the prediction of SDB.

CONCLUSIONS

Undiagnosed SDB was more than threefold higher than expected in these community-dwelling older veterans. Traditional markers of SDB were not specific for predicting clinically relevant SDB.

Moderators of acupuncture effectiveness in breast cancer survivors: Randomized clinical trial (RCT)

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Background: The popularity of acupuncture among cancer patients highlights the need for studying its effectiveness for mitigating side effects of cancer treatments. Insomnia is prevalent among cancer patients and is associated with fatigue and reduced quality of life (QOL). It is also closely linked with depression, sleep apnea, and circadian disruption. Using data form an RCT of acupuncture for insomnia among breast cancer survivors, we examined depression, apnea and circadian factors as moderators of acupuncture effectiveness. Methods: 68 breast cancer survivors (54 years, SD = 9) experiencing insomnia symptoms were randomized to receive 12 sessions of acupuncture (N = 34) or sham (N = 34; using placebo needles). Measures included the Insomnia Severity Index, Brief Fatigue Inventory, and FACT—G, obtained at baseline, mid-treatment (3 weeks), end of treatment (6 weeks), and follow-up (10 weeks). Results: Although acupuncture produced significant improvements from baseline to follow-up in insomnia symptoms, fatigue, and QOL, these improvements did not differ from sham. Compared to sham, the acupuncture produced significantly greater improvements in: 1) insomnia severity (p = 0.03) and QOL (p = 0.02) among those with greater tendency for morning chronotype; 2) fatigue (p = 0.01) among those with lower apnea risk; and 3) QOL (p < 0.001) among those with lower depression scores at baseline. Conclusions: These findings suggest that acupuncture might be more effective among certain subgroups of patients. Moderators of insomnia, fatigue, and QOL include morningness tendency, lower risk for sleep apnea and lower depression scores, respectively. Our findings on depression are in line with prior research that has found that patients with less severe depression may have a greater capacity for acupuncture response perhaps due to higher availability of serotonin. Additional research is needed to test whether acupuncture is a viable treatment option for subgroups of cancer survivors with insomnia. Clinical trial information: NCT01162018.

Daily Actigraphy Profiles Distinguish Depressive and Interepisode States in Bipolar Disorder

Disruptions in activity are core features of mood states in bipolar disorder (BD). This study sought to identify activity patterns that discriminate between mood states in BD. Locomotor activity was collected using actigraphy for six weeks in participants with inter-episode BD type I (n=37) or participants with no lifetime mood disorders (n=39). The 24-hour activity pattern of each participant-day was characterized and within-person differences in activity patterns were examined across mood states. Results show that among participants with BD, depressive days are distinguished from other mood states by an overall lower activity level, and a pattern of later activity onset, a midday elevation of activity, and low evening activity. No distinct within-person activity patterns were found for hypomanic/manic days. Since activity can be monitored non-invasively for extended time periods, activity pattern identification may be leveraged to detect mood states in BD, thereby providing more immediate delivery of care.

Longitudinal assessment of sleep disordered breathing in Vietnam veterans with post-traumatic stress disorder

PURPOSE

Previous work has demonstrated the relatively high prevalence of risk factors for cognitive impairment, such as sleep disordered breathing (SDB) and obesity, in Vietnam War era veterans with post-traumatic stress disorder (PTSD). No data are currently available on the longitudinal stability of SDB as a risk factor for cognitive decline in that population, which this study now reports.

METHODS

Sample consisted of 48 veterans of the Vietnam War with PTSD who completed longitudinal sleep assessments over a 3-year period. The primary outcome measure, the Apnea-Hypopnea Index (AHI) indicator, was determined during standard overnight polysomnography. Body mass index (BMI) was calculated using standard measurements. Measures of cognitive function tapped auditory verbal memory as measured by the Rey Auditory Verbal Learning Test and executive functioning as measured by the Color-Word Interference Test of the Delis-Kaplan Executive Function System battery. Statistical analyses included mixed effects modeling.

RESULTS

In this sample, AHI increased significantly by 2.19 points per year (β=2.19; P<0.005). AHI worsened over the 3-year period, increasing from a mean of 18.7±15.7 to 24.7±17.4 points. Neither BMI nor cognition showed significant change over the 3-year period.

CONCLUSION

SDB worsened in a group of veterans of the Vietnam War with PTSD over a 3-year period. The worsening of SDB over time suggests the need for appropriate countermeasures in populations at risk for progression of the condition.

Millisecond flashes of light phase delay the human circadian clock during sleep

The human circadian timing system is most sensitive to the phase-shifting effects of light during the biological nighttime, a time at which humans are most typically asleep. The overlap of sleep with peak sensitivity to the phase-shifting effects of light minimizes the effectiveness of using light as a countermeasure to circadian misalignment in humans. Most current light exposure treatments for such misalignment are mostly ineffective due to poor compliance and secondary changes that cause sleep deprivation. Using a 16-day, parallel group design, we examined whether a novel sequence of light flashes delivered during sleep could evoke phase changes in the circadian system without disrupting sleep. Healthy volunteers participated in a 2-week circadian stabilization protocol followed by a 2-night laboratory stay. During the laboratory session, they were exposed during sleep to either darkness (n = 7) or a sequence of 2-msec light flashes given every 30 sec (n = 6) from hours 2 to 3 after habitual bedtime. Changes in circadian timing (phase) and micro- and macroarchitecture of sleep were assessed. Subjects exposed to the flash sequence during sleep exhibited a delay in the timing of their circadian salivary melatonin rhythm compared with the control dark condition (p < 0.05). Confirmation that the flashes penetrated the eyelids is presented by the occurrence of an evoked response in the EEG. Despite the robust effect on circadian timing, there were no large changes in either the amount or spectral content of sleep (p values > 0.30) during the flash stimulus. Exposing sleeping individuals to 0.24 sec of light spread over an hour shifted the timing of the circadian clock and did so without major alterations to sleep itself. While a greater number of matched subjects and more research will be necessary to ascertain whether these light flashes affect sleep, our data suggest that this type of passive phototherapy might be developed as a useful treatment for circadian misalignment in humans.

Retino-hypothalamic regulation of light-induced murine sleep

The temporal organization of sleep is regulated by an interaction between the circadian clock and homeostatic processes. Light indirectly modulates sleep through its ability to phase shift and entrain the circadian clock. Light can also exert a direct, circadian-independent effect on sleep. For example, acute exposure to light promotes sleep in nocturnal animals and wake in diurnal animals. The mechanisms whereby light directly influences sleep and arousal are not well understood. In this review, we discuss the direct effect of light on sleep at the level of the retina and hypothalamus in rodents. We review murine data from recent publications showing the roles of rod-, cone- and melanopsin-based photoreception on the initiation and maintenance of light-induced sleep. We also present hypotheses about hypothalamic mechanisms that have been advanced to explain the acute control of sleep by light. Specifically, we review recent studies assessing the roles of the ventrolateral preoptic area (VLPO) and the suprachiasmatic nucleus (SCN). We also discuss how light might differentially promote sleep and arousal in nocturnal and diurnal animals respectively. Lastly, we suggest new avenues for research on this topic which is still in its early stages.

Effects of body mass index-related disorders on cognition: preliminary results

BACKGROUND

Well-known risk factors for cognitive impairment are also associated with obesity. Research has highlighted genetic risk factors for obesity, yet the relationship of those risk factors with cognitive impairment is unknown. The objective of this study was to determine the associations between cognition, hypertension, diabetes, sleep-disordered breathing, and obesity. Genetic risk factors of obesity were also examined.

METHODS

The sample consisted of 369 nondemented individuals aged 50 years or older from four community cohorts. Primary outcome measures included auditory verbal memory, as measured by the Rey Auditory Verbal Learning Test, and executive functioning, as measured by the Color-Word Interference Test of the Delis-Kaplan Executive Function System battery. Apnea-hypopnea index indicators were determined during standard overnight polysomnography. Statistical analyses included Pearson correlations and linear regressions.

RESULTS

Poor executive function and auditory verbal memory were linked to cardiovascular risk factors, but not directly to obesity. Genetic factors appeared to have a small but measureable association to obesity.

CONCLUSION

A direct linkage between obesity and poor executive function and auditory verbal memory is difficult to discern, possibly because nonobese individuals may show cognitive impairment due to insulin resistance and the "metabolic syndrome".

Actigraphy-measured sleep disruption as a predictor of survival among women with advanced breast cancer

BACKGROUND

Poor sleep, prevalent among cancer survivors, is associated with disrupted hormonal circadian rhythms and poor quality of life. Using a prospective research design, this study aimed to clarify the relationship between objective measures of sleep efficiency and sleep disruption with survival among women with advanced breast cancer.

METHOD

We examined sleep quality and duration via wrist-worn actigraphy and sleep diaries for 3 days among 97 women in whom advanced breast cancer was diagnosed (age = 54.6 ± 9.8 years). Sleep efficiency was operationalized using actigraphy as the ratio of total sleep time to total sleep time plus wake after sleep onset.

RESULTS

As hypothesized, better sleep efficiency was found to predict a significant reduction in overall mortality (hazard ratio [HR], 0.96; 95% confidence interval [CI], 0.94-0.98; P < 0.001) at median 6 y follow-up. This relationship remained significant (HR, 0.94; 95% CI, 0.91-0.97; P < 0.001) even after adjusting for other known prognostic factors (age, estrogen receptor status, cancer treatment, metastatic spread, cortisol levels, and depression). Secondary hypotheses were also supported (after adjusting for baseline prognostic factors) showing that less wake after sleep onset (HR, 0.41; 95% CI, 0.25-0.67; P < 0.001), fewer wake episodes, (HR, 0.93; 95% CI, 0.88-0.98; P = 0.007); and shorter wake episode duration (HR, 0.29; 95% CI, 0.14-0.58; P < 0.001) also contributed to reductions in overall mortality.

CONCLUSIONS

These findings show that better sleep efficiency and less sleep disruption are significant independent prognostic factors in women with advanced breast cancer. Further research is needed to determine whether treating sleep disruption with cognitive behavioral and/or pharmacologic therapy could improve survival in women with advanced breast cancer.