Diane Austin

Short Sleep Duration Is Associated with Reduced Leptin, Elevated Ghrelin, and Increased Body Mass Index

Background Sleep duration may be an important regulator of body weight and metabolism. An association between short habitual sleep time and increased body mass index (BMI) has been reported in large population samples. The potential role of metabolic hormones in this association is unknown. Methods and Findings Study participants were 1,024 volunteers from the Wisconsin Sleep Cohort Study, a population-based longitudinal study of sleep disorders. Participants underwent nocturnal polysomnography and reported on their sleep habits through questionnaires and sleep diaries. Following polysomnography, morning, fasted blood samples were evaluated for serum leptin and ghrelin (two key opposing hormones in appetite regulation), adiponectin, insulin, glucose, and lipid profile. Relationships among these measures, BMI, and sleep duration (habitual and immediately prior to blood sampling) were examined using multiple variable regressions with control for confounding factors. A U-shaped curvilinear association between sleep duration and BMI was observed. In persons sleeping less than 8 h (74.4% of the sample), increased BMI was proportional to decreased sleep. Short sleep was associated with low leptin (p for slope = 0.01), with a predicted 15.5% lower leptin for habitual sleep of 5 h versus 8 h, and high ghrelin (p for slope = 0.008), with a predicted 14.9% higher ghrelin for nocturnal (polysomnographic) sleep of 5 h versus 8 h, independent of BMI. Conclusion Participants with short sleep had reduced leptin and elevated ghrelin. These differences in leptin and ghrelin are likely to increase appetite, possibly explaining the increased BMI observed with short sleep duration. In Western societies, where chronic sleep restriction is common and food is widely available, changes in appetite regulatory hormones with sleep curtailment may contribute to obesity.

Predictors of Postschool Employment Outcomes for Young Adults With Severe Disabilities

Although entry into the world of work is a prominent marker of postschool success in the United States, students with severe disabilities often leave high school without the skills, experiences, and supports that lead to meaningful employment. The authors examined the extent to which an array of student, family, and school factors was associated with employment during the 2 years following high school. Having held a paid, community-based job while still in high school was strongly correlated with postschool employment success. In addition, being male and having more independence in self-care, higher social skills, more household responsibilities during adolescence, and higher parent expectations related to future work were all associated with increased odds of employment after school for young adults with severe disabilities. Implications for transition policy and practice are presented along with recommendations for future research addressing the career development of youth with intellectual disabilities, multiple disabilities, and autism.

Factors associated with the early work experiences of adolescents with severe disabilities.

The early work experiences of a nationally representative sample of youth with severe disabilities (i.e., intellectual disabilities, autism, multiple disabilities) were examined. Using data from the National Longitudinal Transition Study-2, we explored the extent to which various student-, family-, school-, and community-level factors were associated with paid work experiences during high school. Findings highlight the elusiveness of early work experiences for many youth with severe disabilities and call attention to malleable factors that may play a role in shaping employment success during high school. Recommendations for research and practice are highlighted.

Effect of body position on vocal tract acoustics: Acoustic pharyngometry and vowel formants

The anatomic basis and articulatory features of speech production are often studied with imaging studies that are typically acquired in the supine body position. It is important to determine if changes in body orientation to the gravitational field alter vocal tract dimensions and speech acoustics. The purpose of this study was to assess the effect of body position (upright versus supine) on (1) oral and pharyngeal measurements derived from acoustic pharyngometry and (2) acoustic measurements of fundamental frequency (F0) and the first four formant frequencies (F1-F4) for the quadrilateral point vowels. Data were obtained for 27 male and female participants, aged 17 to 35 yrs. Acoustic pharyngometry showed a statistically significant effect of body position on volumetric measurements, with smaller values in the supine than upright position, but no changes in length measurements. Acoustic analyses of vowels showed significantly larger values in the supine than upright position for the variables of F0, F3, and the Euclidean distance from the centroid to each corner vowel in the F1-F2-F3 space. Changes in body position affected measurements of vocal tract volume but not length. Body position also affected the aforementioned acoustic variables, but the main vowel formants were preserved.

Effects of Aging on Vocal Fundamental Frequency and Vowel Formants in Men and Women

PURPOSE This study reports data on vocal fundamental frequency (fo) and the first four formant frequencies (F1, F2, F3, F4) for four vowels produced by speakers in three adult age cohorts, in a test of the null hypothesis that there are no age-related changes in these variables. Participants were 43 men and 53 women between the ages of 20 and 92 years. RESULTS The most consistent age-related effect was a decrease in fo for women. Significant differences in F1, F2, and F3 were vowel-specific for both sexes. No significant differences were observed for the highest formant F4. CONCLUSIONS Women experience a significant decrease in fo, which is likely related to menopause. Formant frequencies of the corner vowels change little across several decades of adult life, either because physiological aging has small effects on these variables or because individuals compensate for age-related changes in anatomy and physiology.

Hyoid bone fusion and bone density across the lifespan: prediction of age and sex

The hyoid bone supports the important functions of swallowing and speech. At birth, the hyoid bone consists of a central body and pairs of right and left lesser and greater cornua. Fusion of the greater cornua with the body normally occurs in adulthood, but may not occur at all in some individuals. The aim of this study was to quantify hyoid bone fusion across the lifespan, as well as assess developmental changes in hyoid bone density. Using a computed tomography imaging studies database, 136 hyoid bones (66 male, 70 female, ages 1-to-94) were examined. Fusion was ranked on each side and hyoid bones were classified into one of four fusion categories based on their bilateral ranks: bilateral distant non-fusion, bilateral non-fusion, partial or unilateral fusion, and bilateral fusion. Three-dimensional hyoid bone models were created and used to calculate bone density in Hounsfield units. Results showed a wide range of variability in the timing and degree of hyoid bone fusion, with a trend for bilateral non-fusion to decrease after age 20. Hyoid bone density was significantly lower in adult female scans than adult male scans and decreased with age in adulthood. In sex and age estimation models, bone density was a significant predictor of sex. Both fusion category and bone density were significant predictors of age group for adult females. This study provides a developmental baseline for understanding hyoid bone fusion and bone density in typically developing individuals. Findings have implications for the disciplines of forensics, anatomy, speech pathology, and anthropology.