Iris Leng

Maternal Depressive Symptomatology: 16-Month Follow-up of Infant and Maternal Health-Related Quality of Life

Purpose: The purpose of this study was to document risk factors for depressive symptoms during the postpartum period among working mothers and to determine longitudinal effects of depressive symptoms on maternal health-related quality of life and infant health and development. Methods: Mother-infant dyads from a community-based cohort study of working mothers were recruited when infants were 4 months old and were interviewed every 4 months until infants were 16 months old. Depressive symptoms and health-related quality of life were assessed using the Center for Epidemiologic Studies Depression Scale and the Short Form-12 Health Survey, respectively. Infant development and health-related quality of life were measured with the Ages and Stages Questionnaire and the Infant-Toddler Quality of Life Questionnaire, respectively. Results: Depressive symptoms were elevated among mothers who were younger, less educated, African American, unmarried, and impoverished. Mothers with significant depressive symptoms had significantly poorer physical and mental health-related quality of life, reported greater pain for their infant, and had more health-related concerns about their child. Maternal depressive symptoms at 4 months predicted infant poorer health-related quality of life at 8, 12, and 16 months. Conclusions: Several characteristics, including age, education level, race, marital status, and poverty, can help primary care physicians identify working mothers at risk for depressive symptoms. Identification of these symptoms is important; they are correlated with poorer maternal health-related quality of life and they predict poorer childrens health-related quality of life.

Relationship of physical function to vastus lateralis capillary density and metabolic enzyme activity in elderly men and women

Background and aims: There are no data showing whether or not age-related declines in physical function are related to in vitro properties of human skeletal muscle. The purpose of this study was to determine whether physical function is independently associated with histologic and metabolic properties of skeletal muscle in elderly adults. Methods: The study was a cross-sectional observational study of 39 sedentary, older (60–85 yrs) men and women. A needle biopsy of the vastus lateralis for assessment of muscle fiber type, fiber area, capillary density and citrate synthase and aldolase activities was performed. Physical function tests included the Short Physical Performance Battery (balance, walking speed, and chair rise time), as well as self-reported disability. Results: Total fiber area (R=−0.41, p=0.02), number of Type II fibers (R=− 0.33, p=0.05), and aldolase activity (R=−0.54, p=0.01) were inversely related to age. Persons who reported greater difficulty with daily activities had lower capillary density (R=−0.51, p=0.03) and lower citrate synthase activity (R=−0.66, p=0.03). Walking speed was directly related to fiber area (R=0.40, p=0.02), capillary density (R=0.39, p=0.03), citrate synthase (R=0.45, p=0.03) and aldolase (R=0.55, p<0.01) activities, even after adjustment for age, BMI and disease status. Conclusions: In older adults, skeletal muscle capillary density and metabolic enzymatic activity are independent predictors of lower extremity physical function.

Intraindividual variability in domain-specific cognition and risk of mild cognitive impairment and dementia.

Intraindividual variability among cognitive domains may predict dementia independently of interindividual differences in cognition. A multidomain cognitive battery was administered to 2305 older adult women (mean age 74 years) enrolled in an ancillary study of the Womens Health Initiative. Women were evaluated annually for probable dementia and mild cognitive impairment (MCI) for an average of 5.3 years using a standardized protocol. Proportional hazards regression showed that lower baseline domain-specific cognitive scores significantly predicted MCI (N = 74), probable dementia (N = 45), and MCI or probable dementia combined (N = 101) and that verbal and figural memory predicted each outcome independently of all other cognitive domains. The baseline intraindividual standard deviation across test scores (IAV Cognitive Domains) significantly predicted probable dementia and this effect was attenuated by interindividual differences in verbal episodic memory. Slope increases in IAV Cognitive Domains across measurement occasions (IAV Time) explained additional risk for MCI and MCI or probable dementia, beyond that accounted for by interindividual differences in multiple cognitive measures, but risk for probable dementia was attenuated by mean decreases in verbal episodic memory slope. These findings demonstrate that within-person variability across cognitive domains both at baseline and longitudinally independently accounts for risk of cognitive impairment and dementia in support of the predictive utility of within-person variability.

Return to Work, Economic Hardship, and Women's Postpartum Health

This study followed a sample of 217 new mothers in a North Carolina county as they returned to work full-time, measuring their mental and physical health-related quality of life through 16 months postpartum. In general, working mothers of infants had mental health scores that were comparable to the general population of U.S. women, and physical health that was slightly better than women in general. Using ANCOVA and controlling for important demographic characteristics, health-related quality of life was compared between mothers experiencing low and high levels of economic hardship. Across the study period, women with high economic hardship, who constituted 30.7% of the sample, had levels of mental and physical health below those of women with low economic hardship. Mothers with high economic hardship also had less stable health trajectories than mothers with low economic hardship. The findings highlight the importance of reconsidering the traditionally accepted postpartum recovery period of six weeks and extending benefits, such as paid maternity and sick leave, as well as stable yet flexible work schedules.

Improved Knee Extensor Strength with Resistance Training Associates with Muscle Specific miRNAs in Older Adults

Regular exercise, particularly resistance training (RT), is the only therapy known to consistently improve muscle strength and quality (force per unit of mass) in older persons, but there is considerable variability in responsiveness to training. Identifying sensitive diagnostic biomarkers of responsiveness to RT may inform the design of a more efficient exercise regimen to improve muscle strength in older adults. MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression. We quantified six muscle specific miRNAs (miR-1, -133a, -133b, -206, -208b and -499) in both muscle tissue and blood plasma, and their relationship with knee extensor strength in seven older (age=70.5 ± 2.5 years) adults before and after 5 months of RT. MiRNAs differentially responded to RT; muscle miR-133b decreased, while all plasma miRNAs tended to increase. Percent changes in knee extensor strength with RT showed strong positive correlations with percent changes in muscle miR-133a, -133b, and -206 and with percent changes in plasma and plasma/muscle miR-499 ratio. Baseline level of plasma or plasma/muscle miR-499 ratio further predicts muscle response to RT, while changes in muscle miR-133a, -133b, and -206 may correlate with muscle TNNT1 gene alternative splicing in response to RT. Our results indicate that RT alters muscle specific miRNAs in muscle and plasma, and that these changes account for some of the variation in strength responses to RT in older adults.

Intervening on spontaneous physical activity to prevent weight regain in older adults: Design of a randomized, clinical trial

There is a need to identify evidenced-based obesity treatments that are effective in maintaining lost weight. Weight loss results in reductions in energy expenditure, including spontaneous physical activity (SPA) which is defined as energy expenditure resulting primarily from unstructured mobility-related activities that occur during daily life. To date, there is little research, especially randomized, controlled trials, testing strategies that can be adopted and sustained to prevent declines in SPA that occur with weight loss. Self-monitoring is a successful behavioral strategy to facilitate behavior change, so a provocative question is whether monitoring SPA-related energy expenditure would override these reductions in SPA, and slow weight regain. This study is a randomized trial in older, obese men and women designed to test the hypothesis that adding a self-regulatory intervention (SRI), focused around self-monitoring of SPA, to a weight loss intervention will result in less weight and fat mass regain following weight loss than a comparable intervention that lacks this self-regulatory behavioral strategy. Participants (n=72) are randomized to a 5-month weight loss intervention with or without the addition of a behavioral component that includes an innovative approach to promoting increased SPA. Both groups then transition to self-selected diet and exercise behavior for a 5-month follow-up. Throughout the 10-month period, the SRI group is provided with an intervention designed to promote a SPA level that is equal to or greater than each individuals baseline SPA level, allowing us to isolate the effects of the SPA self-regulatory intervention component on weight and fat mass regain.

Effects of Longitudinal Glucose Exposure on Cognitive and Physical Function: Results from the Action for Health in Diabetes Movement and Memory Study

To test whether average long‐term glucose exposure is associated with cognitive and physical function in middle‐aged and younger‐old adults with type 2 diabetes mellitus.

Risk Factor Burden, Heart Failure, and Survival in Women of Different Ethnic Groups: Insights From the Women’s Health Initiative

Background: The higher risk of heart failure (HF) in African-American and Hispanic women compared with white women is related to the higher burden of risk factors (RFs) in minorities. However, it is unclear if there are differences in the association between the number of RFs for HF and the risk of development of HF and death within racial/ethnic groups. Methods and Results: In the WHI (Women’s Health Initiative; 1993–2010), African-American (n=11 996), white (n=18 479), and Hispanic (n=5096) women with 1, 2, or 3+ baseline RFs were compared with women with 0 RF within their respective racial/ethnic groups to assess risk of developing HF or all-cause mortality before and after HF, using survival analyses. After adjusting for age, socioeconomic status, and hormone therapy, the subdistribution hazard ratio (95% confidence interval) of developing HF increased as number of RFs increased (P<0.0001, interaction of race/ethnicity and RF number P=0.18)—African-Americans 1 RF: 1.80 (1.01–3.20), 2 RFs: 3.19 (1.84–5.54), 3+ RFs: 7.31 (4.26–12.56); Whites 1 RF: 1.27 (1.04–1.54), 2 RFs: 1.95 (1.60–2.36), 3+ RFs: 4.07 (3.36–4.93); Hispanics 1 RF: 1.72 (0.68–4.34), 2 RFs: 3.87 (1.60–9.37), 3+ RFs: 8.80 (3.62–21.42). Risk of death before developing HF increased with subsequent RFs (P<0.0001) but differed by racial/ethnic group (interaction P=0.001). The number of RFs was not associated with the risk of death after developing HF in any group (P=0.25; interaction P=0.48). Conclusions: Among diverse racial/ethnic groups, an increase in the number of baseline RFs was associated with higher risk of HF and death before HF but was not associated with death after HF. Early RF prevention may reduce the burden of HF across multiple racial/ethnic groups.

Effects of aging and levodopa on the laryngeal adductor reflex in rats

Dopaminergic neurotransmission plays an essential role in sensorimotor function, and declines with age. Previously, we found the laryngeal adductor reflex (LAR) was increased in excitation by a dopamine receptor antagonist. If this airway-protective reflex is similarly affected by aging, it will interfere with volitional control in older adults. The current study tested whether the LAR was affected by aging, and whether such deficits were reversed by levodopa administration in aging rats. We recorded thyroarytenoid (TA) muscle activity at rest and during elicitation of LAR responses by stimulation of the internal branch of the superior laryngeal nerve (iSLN) in 6-, 18- and 30-month-old rats under alpha-chloralose anesthesia. Using paired stimuli at different inter-stimulus intervals (ISIs), LAR central conditioning, resting muscle activity, and reflex latency and amplitudes were quantified. Numbers of dopaminergic neurons in the substantia nigra pars compacta (SNpc) were measured using tyrosine hydroxylase staining. We found: (1) increased resting TA muscle activity and LAR amplitude occurred with fewer dopaminergic neurons in the SNpc in 18- and 30-month-old rats; (2) decreases in LAR latency and increases in amplitude correlated with reduced numbers of dopaminergic neurons in the SNpc; (3) test responses were greater at 1000ms ISI in 18-month-old rats compared with 6-month-old rats; and (4) levodopa administration further increased response latency but did not alter muscle activity, response amplitude, or central conditioning. In conclusion, increases in laryngeal muscle activity levels and reflex amplitudes accompanied age reductions in dopaminergic neurons but were not reversed with levodopa administration.

Empowered with Movement to Prevent Obesity & Weight Regain (EMPOWER): Design and methods

Promoting lasting weight loss among older adults is an important public health challenge. Participation in physical activity aids in weight loss and is important for the maintenance of physical function and quality of life. However, traditional intensive lifestyle interventions place a focus on discrete bouts of structured activity, leaving much of the remainder of the day for sedentary behavior. Structured exercise and weight loss programs often produce short-term weight loss that is typically followed by weight regain, and older adults are more likely to regain weight as fat mass rather than lean mass. Preliminary evidence suggests a focus on day-long movement intended to minimize time spent sitting produces better short-term weight loss and weight maintenance. Herein we describe the design and methods for a three-arm randomized controlled trial comparing mHealth-supported weight loss (WL) + structured exercise (EX); WL + a novel daily movement intervention (SitLess); and WL + EX + SitLess. Older adults (N = 180) will be randomly assigned to one of the three interventions, each comprised of a 6-month intensive phase; a 3-month transition phase; and a 9-month maintenance phase. The primary aim of the study is to determine whether the addition of SitLess to a traditional intensive lifestyle intervention comprised of dietary weight loss and structured exercise produces a larger 18-month reduction in body weight relative to WL + EX and WL + SitLess.