Sleep in Older African Americans and Caucasians at Risk for Sleep-Disordered Breathing

This study explored differences in sleep between older African Americans (AA) and Caucasians (CA) at risk for sleep-disordered breathing. Seventy AA and 70 CA were compared on ambulatory monitoring sleep variables and on self-reports on health and socioeconomic status (SES). After controlling for SES and health covariates, CA woke up significantly more often than AA (p = .018), but there were no other differences in sleep variables between the two groups. Time awake at night was related to being male, more depression, less walking, and lower income, whereas having more awakenings during the night was related to being CA, higher apnea-hypopnea index, and higher periodic leg movement index. Importance of inclusion of SES, health, and other covariates in studies exploring racial differences in sleep are discussed.     

Behavioral correlates of sleep-disordered breathing in older women

STUDY OBJECTIVES: To examine the association between SDB and subjective measures of daytime sleepiness, sleep quality, and sleep related quality of life in a large cohort of primarily community-dwelling older women, specifically considering the relative importance of sleep duration in mediating these associations. DESIGN: Cross-sectional. The functional outcome measures of interest were daytime sleepiness (using the Epworth Sleepiness Scale, ESS), sleep-related symptoms (Pittsburgh Sleep Quality Index, PSQI), and sleep related quality of life (Functional Outcomes of Sleep Questionnaire, FOSQ). ANOVA and regression analyses examined the association between SDB severity (measured by indices of breathing disturbances and overnight oxygen saturation) and sleep time (by actigraphy) and these outcome measures. Regression models were adjusted for age, body mass index (BMI), and a medical comorbidity index. We specifically explored whether associations with indices of SDB were mediated by sleep deprivation by adjusting models for actigraphy-determined average total sleep time (TST) during the night. SETTING: Community-based sample examined in home and outpatient settings. PARTICIPANTS: 461 surviving older women from the multicenter Study of Osteoporotic Fractures were examined during Visit 8 from 2002-03. All participants underwent in-home overnight polysomnography for one night and wrist actigraphy for a minimum of 3 24-h periods and completed the above functional outcomes questionnaires. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Participants were aged 82.9 +/- 3.5 (mean +/- SD) years, had BMI of 27.9 +/- 5.1 kg/m2, and had an apnea-hypopnea index (AHI) of 15.7 +/- 15.1. AHI and TST demonstrated a weak correlation (r = -0.15). ESS score individually demonstrated a modest association with AHI, oxygen desaturation, and TST. The association of ESS score and AHI--but not oxygen desaturation-was attenuated to some extent by adjustment for TST. PSQI and FOSQ scores were not associated with measures of SDB severity or TST. CONCLUSIONS: After adjustment for TST, SDB severity in community-dwelling older women was not independently associated with self-reported daytime sleepiness, although there may be a modest association that is mediated through reduced TST. In older women, SDB severity was not associated with indices of sleep related symptoms or sleep related quality of life.     

Nasal obstruction as a risk factor for sleep-disordered breathing

Nasal obstruction frequently has been associated with sleep-disordered breathing as a potential etiologic factor. Nasal obstruction results in pathologic changes in airflow velocity and resistance. Experimentally produced nasal obstruction increases resistance and leads to sleep-disordered breathing events, including apnea, hypopnea, and snoring. Clinical research examining the correlation between nasal obstruction and sleep-disordered breathing is limited, especially in regard to patients with conditions that increase nasal resistance, such as rhinitis and sinusitis. To further identify risk factors for sleep-disordered breathing, the role of chronic and acute nasal congestion was investigated in a population-based sample. Data on nasal congestion history and sleep problems were obtained by questionnaire (n = 4927) and by objective in-laboratory measurement (n = 911). Participants who often or almost always experienced nighttime symptoms of rhinitis (5 or more nights a month) were significantly (p < 0.0001) more likely to report habitual snoring (3 to 7 nights a week), chronic excessive daytime sleepiness, or chronic nonrestorative sleep than were those who rarely or never had symptoms. Habitual snorers had significantly (p< 0.02) lower air flow than nonsnorers, although a linear relation between decreased airflow and sleep-disordered breathing severity did not exist. Participants who reported nasal congestion due to allergy were 1.8 times more likely to have moderate to severe sleep-disordered breathing than were those without nasal congestion due to allergy. Men and women with nasal obstruction, especially chronic nighttime symptoms of rhinitis, are significantly more likely to be habitual snorers, and a proportion also may have frequent episodes of apnea and hypopnea, indicative of severe sleep-disordered breathing. Because allergic rhinitis is a common cause of nasal obstruction and it is a modifiable risk factor, further study of this association is warranted. (J Allergy Clin Immunol 1997;99:S757-62.)     

Sleep disorders in African Americans and Caucasian Americans: a meta-analysis

Previous research suggests that ethnic groups differ in the prevalence and severity of disordered sleep symptoms. This study used meta-analysis to determine the magnitude of ethnic differences between African Americans (AAs) and Caucasian Americans (CAs) in insomnia symptoms and sleep-disordered breathing (SDB). It also used moderator analyses to explore the variability in these effect sizes. Thirteen studies measuring insomnia symptoms and 10 studies measuring SDB met inclusion criteria and represented thousands of adult AAs and CAs. Results indicate AAs have a higher prevalence and greater severity of SDB, but CAs report more insomnia symptoms. These results indicate a need for a multi-ethnic approach to the assessment and treatment of sleep disorders.     

Genetic and environmental influences in sleep-disordered breathing in older male twins

STUDY OBJECTIVES: To estimate the extent to which genetic factors contribute to the variation in several indices of sleep-disordered breathing in elderly male twins. DESIGN AND SETTING: A biometric genetic study based on data from unattended Edentrace recordings in a sample of elderly male twins. PARTICIPANTS: 122 World War II male veteran twin pairs, including 68 monozygotic pairs aged 78.9 (+/- 2.7) years and 54 dizygotic pairs aged 78.4 (+/- 2.4) years. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: The average (+/- SD) respiratory disturbance index for this sample was 17.2 +/- 14.5, the average (+/- SD) oxygen desaturation index was 18.8 +/- 16.4, and the average (+/- SD) minimum SaO2 level was 79.6 +/- 8.1%. Intraclass twin-pair correlations for log-transformed respiratory disturbance index were 0.59 in monozygotic pairs and 0.36 in dizygotic pairs. For oxygen desaturation index, intraclass correlations were 0.44 in monozygotic pairs and 0.24 in dizygotic pairs. For minimum SaO2, intraclass correlations were 0.38 and 0.11, respectively. Maximum likelihood estimates of heritability with associated 95% confidence intervals were 37% [22%, 52%] for respiratory disturbance index, 36% [19%, 53%] for oxygen desaturation index, and 10% [0%, 30%] for minimum SaO2. Adjustments of sleep-disordered breathing measures for age, body mass index, and waist and neck circumference had minimal effect on estimates of heritability. CONCLUSIONS: The present data indicate that sleep-disordered breathing, even in old age, is determined, in part, by genetic factors.     

Acquired immunodeficiency syndrome in older African Americans

The purpose of this study was to determine if older African Americans are disproportionately affected by acquired immunodeficiency syndrome (AIDS), and to review the clinical impact of AIDS and the importance of prevention and treatment efforts. A review of the literature and statistics was obtained using Medline and the AIDS Public Information Data Set offered by the Centers for Disease Control and Prevention. Twenty-seven percent of the U.S. population is above the age of 50, and the number of AIDS cases in this group is growing, with African Americans accounting for the highest proportion of cases and deaths. Testing for HIV may be delayed and symptoms attributed to other illnesses. Though 5% of new cases occur in those over 50, prevention programs, testing, and the perception of risk by providers may be insufficient. There are few research studies on HIV treatment in older patients and no specific guidelines for antiretroviral treatments available. Although death rates for AIDS has been declining, adults over 50 still have the highest mortality rate. Co-morbid conditions, such as heart disease and hypertension, may require taking multiple drugs, which may complicate treatment. Increasing heterosexual transmission rates and a lack of information on HIV reinforces the need for specific prevention programs targeted toward older African Americans.     

Differential aerobic exercise-induced changes in plasma aldosterone between African Americans and Caucasians

Aldosterone influences the kidney's regulation of blood pressure (BP), but aldosterone can contribute to the pathogenesis of hypertension. Blood pressure is reduced with aerobic exercise training (AEX), but the extent to which plasma aldosterone (PA) levels change is unclear. The purpose of this study was to determine whether 6 months of AEX changed PA levels, 24 h sodium (Na(+)) excretion and BP in prehypertensive and hypertensive subjects and whether these changes differed according to ethnicity. The study was performed in the Kinesiology Department at the University of Maryland, College Park, and 35 (22 Caucasian; 13 African American) sedentary prehypertensive and hypertensive subjects completed 6 months of AEX. Blood samples were collected under fasting and supine conditions, and PA was measured by radioimmunoassay. In total population aerobic exercise training increased maximal oxygen consumption (24 +/- 0.8 versus 28 +/- 1 ml kg(-1) min(-1), P < 0.001) and decreased PA levels (97 +/- 11 versus 72 +/- 6 pg ml(-1), P = 0.01), body mass index (28 +/- 0.5 versus 28 +/- 0.5 kg m(-2), P = 0.004) and weight (85 +/- 2 versus 83 +/- 2 kg, P = 0.003). Aerobic exercise training decreased PA levels (from 119 +/- 16 to 81 +/- 7 pg ml(-1), P = 0.02) in the Caucasians but there was no change in BP or Na(+) excretion. African American participants had no significant changes in PA levels, BP and Na(+) excretion. Plasma aldosterone levels were 47% lower at baseline (P = 0.01) and 30% lower after AEX (P = 0.04) in African American participants compared with Caucasians. Baseline (P = 0.08) and final PA levels (P = 0.17) did not differ between the two groups after accounting for baseline and final intra-abdominal fat, respectively. The reduction in PA levels with AEX appeared to be driven by the change in PA levels in Caucasian participants. Fat distribution contributed to the ethnic differences in PA levels.     

Screening for subclinical sleep-disordered breathing

We evaluated self-administered questionnaires and short sleep studies in screening for sleep-disordered breathing (SDB) in 40 hypertensive men ages 36-66 unselected for symptoms. Each subject completed a questionnaire including questions on sleep-related symptoms and underwent overnight polysomnography in which we evaluated the apnea-hypopnea index (AHI) and the percentage of time during which arterial O2 saturation was less than 90% (T90). The first 90 min of overnight study was evaluated separately, and 10 subjects with an AHI greater than or equal to 10 also underwent late afternoon nap study. By overnight polysomnography, 48% of the cohort had an AHI greater than or equal to 10, and 35% had a T90 greater than or equal to 10%. Using linear regression, we found no features of the symptom questionnaire that strongly predicted AHI. Only self-reported snoring and baseline arterial Po2 significantly predicted T90. The AHI and T90 were not significantly correlated. Considering an AHI greater than or equal to 10 in the overnight study as "abnormal" and an AHI greater than or equal to 10 on the short study as a "positive" test, the specificity of the AHI in the first 90 min was 100% (21/21), and the sensitivity was 42% (8/19). The sensitivity of the nap study was 60% (6/10). We conclude that in a cohort unselected for symptoms, the ability of self-administered questionnaires to predict SDB was low; short studies were only moderately sensitive for detecting an AHI greater than or equal to 10, and the AHI was not a major determinant of nocturnal desaturation.     

HLA disease association and protection in HIV infection among African Americans and Caucasians

In a previous investigation, we demonstrated an increased progression of overt AIDS in the African American population compared to the Caucasian population as reflected by the significantly lower absolute number of CD4+ lymphocytes detected in the African American population in an earlier study. The present study elucidates some of the possible genetic factors which may contribute to disease association or protection against HIV infection. The HLA phenotypes expressed as A, B, C, DR and DQw antigens were revealed by the Amos-modified typing procedure. NIH scoring was utilized to designate positive cells taking up trypan blue. A test of proportion equivalent to the chi 2 approximation was used to compare the disease population (n = 62; 38 African Americans, 24 Caucasians) to race-matched normal heterosexual local controls (323 African Americans, 412 Caucasians). Significant p values were corrected for the number of HLA antigens tested. HLA markers associated with possible protection from infection for African Americans were Cw4 and DRw6, whereas Caucasians expressed none. Disease association markers present in the African American population were A31, B35, Cw6, Cw7, DR5, DR6, DRw11, DRw12, DQw6 and DQw7, whereas in the Caucasian population A28, Aw66, Aw48, Bw65, Bw70, Cw7, DRw10, DRw12, DQw6 and DQw7 were demonstrated. The highest phenotypic frequency for a disease association marker in the study was for HLA-DR5 (62.9%) in the HIV-infected African American population without Kaposi's sarcoma compared to a frequency of 28.9% for the regional control group (p = 0.0012). We conclude that genetic factors do have a role in HIV infection since only 50-60% of those exposed to the AIDS virus will become infected.     

Haplotype structure of the beta adrenergic receptor genes in US Caucasians and African Americans

The beta-adrenergic receptors (beta-AR) are G protein-coupled receptors activated by epinephrine and norepinephrine and are involved in a variety of their physiological functions. Previously, three beta-AR genes (ADRB1, ADRB2 and ADRB3) were resequenced, identifying polymorphisms that were used in genetic association studies of cardiovascular and metabolic disorders. These studies have produced intriguing but inconsistent results, potentially because the known functional variants: ADRB1 Arg389Gly and Gly49Ser, ADRB2 Arg16Gly and Gln27Glu, and ADRB3 Arg64Trp provided an incomplete picture of the total functional diversity at these genes. Therefore, we created marker panels for each beta-AR gene that included the known functional markers and also other markers evenly spaced and with sufficient density to identify haplotype block structure and to maximize haplotype diversity. A total of 27 markers were genotyped in 96 US Caucasians and 96 African Americans. In both populations and for each gene, a single block with little evidence of historical recombination was observed. For each gene, haplotype captured most of the information content of each functional locus, even if that locus was not genotyped, and presumably haplotype would capture the signal from unknown functional loci whose alleles are of moderate abundance. This study demonstrates the utility of using beta-AR gene haplotype maps and marker panels as tools for linkage studies on beta-AR function.     

C-reactive protein and sleep-disordered breathing

STUDY OBJECTIVES: Over a 2-month period, to evaluate serum levels of C-reactive protein (CRP) in new patients with obstructive sleep apnea syndrome (OSAS), upper airway resistance syndrome (UARS), and absence of important comorbidity, as well as in normal controls. DESIGN: Cross-sectional analysis. SETTING: Sleep disorders clinic. PATIENTS: 239 successively monitored subjects: 156 subjects were diagnosed with OSAS, 39 with UARS, and 54 controls. INTERVENTIONS: none. MEASUREMENTS AND RESULTS: Clinical information (neurologic, general medical, and otolaryngology examination), body mass index, neck circumference, hip-waist ratio, Epworth Sleepiness Scale, 3 fatigue scales, Sleep Disorders Questionnaire, serum CRP, and polysomnography were collected. Analysis of variance indicated a significant difference between the groups for diastolic blood pressure, respiratory disturbance index, lowest SaO2, and body mass index. The mean serum CRP level was normal in all 3 groups. Only 15 (14 OSAS and 1 UARS) out of 239 subjects had high serum CRP values. CRP levels were significantly correlated with body mass index, esophageal pressures, hip-waist ratio, neck circumference, and blood pressure. Only body mass index was significantly associated with high CRP values; multiple regression showed: adjusted R2 = 0.115, beta = 0.345, P <.001. When men and women were considered separately, body mass index was again significantly associated with high CRP levels. CONCLUSION: Obesity is a risk factor for high serum CRP levels in patients with sleep-disordered breathing, as in the general population.     

The Sleep of African Americans: A Comparative Review

Researchers have not thoroughly assessed the sleep of African Americans (AAs) despite the recent increased attention to ethnic research. This article reviews the sleep and epidemiological literatures to assess AA sleep. Although the limited data were sometimes inconsistent, they suggest that AAs sleep worse than Caucasian Americans. AAs take longer to fall asleep, report poorer sleep quality, have more light and less deep sleep, and nap more often and longer. AAs have a higher prevalence of sleep-disordered breathing and exhibit more risk factors for poor sleep. These differences are concentrated in young- and middle-age adults. There are no sleep disorders treatment data for AAs. These data support further research into ethnic differences in both normal and disturbed sleep.     

Associates of bone mineral density in older African Americans

OBJECTIVES: To assess correlates of bone mineral density (BMD) in older African Americans. PARTICIPANTS: 189 women and 115 men over age 64. METHODS: Variables investigated: BMD by dual X-ray absorptiometry (DXA), medications, cardiovascular disease risk factors, demographic, lifestyle factors and functional status. Variables showing univariate correlation with BMD (p < or = 0.1) were entered into sex-stratified linear regression models. RESULTS: Age range 67-96 (mean 75). The mean BMD (gm/ cm2 +/- standard deviation) is reported for three sites. Total body: 1.03 (+/- 0.12) in women, 1.21 (+/- 0.11) in men. Spine: 1.05 (+/- 0.24) in women, 1.22 (+/- 0.26) in men. Total hip: 0.85 (+/- 0.15) in women, 1.04 (+/- 0.17) in men. Gender was significantly associated with BMD (t-test, p < 0.001). The R2 for tested variables were highly significant only for weight. Age was only significant for total hip in women (p < 0.05). Each kilogram of weight change was associated with a 5.3-6.8 mg/cm2 change in BMD. CONCLUSIONS: In a population-based cohort of older African Americans, average BMD was significantly greater in men than women. Weight accounted for most of the explained variability (R2) in BMD; age added little to the overall R2. Lower-weight, older African-American men and women are at significantly increased risk for low BMD and, thus, likely to be at greater risk for osteoporotic fracture.     

Variation in symptoms of sleep-disordered breathing with race and ethnicity: the Sleep Heart Health Study

STUDY OBJECTIVES: To examine the relation of sleep-related symptoms to race and ethnicity in a diverse sample of middle-aged and older men and women. DESIGN: Cross-sectional questionnaire survey. SETTING: In the initial phase of the Sleep Heart Health Study, men and women enrolled in participating epidemiologic cohort studies were surveyed. PARTICIPANTS: 13,194 men and women 40 years of age and older, including 11,517 non-Hispanic white, 648 black, 643 American Indian, 296 Hispanic, and 90 Asian-Pacific Islander. INTERVENTIONS: Not applicable. MEASUREMENTS AND RESULTS: After adjustment for BMI and other factors, frequent snoring was more common among Hispanic women (odds ratio (OR) = 2.25, 95% confidence interval (CI) = 1.48, 3.42) and black women (OR = 1.55, 95% Ci = 1.13, 2.13) than among non-Hispanic white women. Hispanic men were significantly more likely to report frequent snoring than non-Hispanic white men (OR = 2.30, 95% CI = 1.43, 3.69). Black, American Indian, and Asian men did not differ significantly from white men in snoring prevalence. American Indian women were significantly more likely to report breathing pauses during sleep than their white, non-Hispanic counterparts (OR = 1.52, 95% CI 1.03, 2.24), although polysomnography data on a subset of the sample suggested that the association between this symptom reported on questionnaire and objective evidence of sleep-disordered breathing may be weaker among American Indians than among other groups. Mean Epworth Sleepiness Scale scores were slightly higher in black men and women than in their white, non-hispanic counterparts. CONCLUSIONS: Frequent snoring was more common among black and Hispanic women and Hispanic men than among their white non-Hispanic counterparts, even after adjusting for BMI and other factors. Further research including polysomnography and objective measurements of sleepiness is needed to assess the physiologic and clinical significance of these findings.