Birth weight and cognitive function in early adulthood: the Australian Aboriginal birth cohort study.

It has been suggested that in addition to genetic factors, fetal and post-natal growth influence cognition in early adulthood. However, most studies have been in developed populations, so it is unclear if the same findings would be seen in other, less developed, settings, and have used testing tools not applicable to an Australia Aboriginal population. This study investigated the relationships between cognitive function in early adulthood and birth weight and contemporary height. Simple reaction time (SRT), choice reaction time (CRT) and working memory (WM) were assessed using the CogState battery. A significant association was seen between birth weight and SRT in early adulthood, but not with the other two cognitive measures. Urban dwellers had significantly shorter SRT and CRT than their remote counterparts. Contemporary body mass index and maternal age were associated with CRT. Only fetal growth restriction was associated with WM, with greater WM in those with restricted growth. No associations were seen with contemporary height. These results suggest that fetal growth may be more important than the factors influencing post-natal growth in terms of cognition in early adulthood in this population, but that the associations may be inconsistent between cognitive outcomes. Further research is required to identify whether similar associations are seen in other, similar, populations and to assess why differences in cognitive outcome measures are seen.

Associations between oral health and height in an indigenous Australian birth cohort.

OBJECTIVE: Evidence suggests that taller individuals have better health than their shorter counterparts. This study aimed to test the hypothesis that shorter participants in wave-3 of the Aboriginal Birth Cohort (ABC) study, a prospective longitudinal investigation of Indigenous Australian individuals born 1987-1990 at an Australian regional hospital, would have more caries and periodontal disease experience than their taller counterparts. METHODS: Data were collected through oral clinical examinations, anthropometric measures and self-report questionnaires. The outcome variables were participants' caries (mean DMFT) and periodontal disease experience (moderate or severe periodontal disease as defined by the Centre for Disease Control), with height as an explanatory variable. Antecedent anthropometric, socio-demographic, sugar consumption frequency, dental behaviour and substance use variables were used as possible confounders. Linear regression was used in the analysis of caries experience, while adjusted prevalence ratios were used for prevalence of moderate or severe periodontal disease. RESULTS: Higher DMFT was found among participants in the shortest tertile (B=1.02, 95% CI=0.02-2.02) and those who consumed sweets every day or a few days a week (B=1.08, 95% CI=0.11-2.05), while lower DMFT was found among those owning a toothbrush (B=0.80, 95% CI=-0.22-1.82). Periodontal disease was positively associated with the shortest tertile (adjusted PR=1.39, 95% CI=0.96-1.82) and negatively associated with toothbrush ownership (adjusted PR=0.50, 95% CI=0.34-0.66). CONCLUSION: The hypothesis that shorter participants in wave-3 of the ABC study would have higher levels of caries and periodontal disease was confirmed.

Associations between area-level disadvantage and DMFT among a birth cohort of Indigenous Australians.

BACKGROUND: Individual-level factors influence DMFT, but little is known about the influence of community environment. This study examined associations between community-level influences and DMFT among a birth cohort of Indigenous Australians aged 16-20 years. METHODS: Data were collected as part of Wave 3 of the Aboriginal Birth Cohort study. Fifteen community areas were established and the sample comprised 442 individuals. The outcome variable was mean DMFT with explanatory variables including diet and community disadvantage (access to services, infrastructure and communications). Data were analysed using multilevel regression modelling. RESULTS: In a null model, 13.8% of the total variance in mean DMFT was between community areas, which increased to 14.3% after adjusting for gender, age and diet. Addition of the community disadvantage variable decreased the variance between areas by 4.8%, indicating that community disadvantage explained one-third of the area-level variance. Residents of under-resourced communities had significantly higher mean DMFT (ß = 3.86, 95% CI 0.02, 7.70) after adjusting for gender, age and diet. CONCLUSIONS: Living in under-resourced communities was associated with greater DMFT among this disadvantaged population, indicating that policies aiming to reduce oral health-related inequalities among vulnerable groups may benefit from taking into account factors external to individual-level influences.

A retrospective longitudinal study of caries development in an Australian Aboriginal birth cohort.

There are a limited number of longitudinal investigations that examine the progression of dental disease in an indigenous population. Dental examinations of a cohort of indigenous Australians born in Darwin (Australia) between 1987 and 1990 were conducted at ages 6-8 and 11-13 years as part of the Child Dental Health Survey, and 18-20 years as part of the longstanding prospective Aboriginal Birth Cohort (ABC) study. Data was available at all ages for 145 participants. The percent DMFT >0 increased from 17.2 to 44.1 to 81.4%, representing a linear trajectory, whereas mean DMFT increased from 0.3 to 1.0 to 5.6, representing an exponential trajectory. Both trends were significant. At age 18-20 years, the percent DMFT >0 among ABC study participants was 1.2 times that of their counterparts at a national level. The differences were more marked when dental caries severity was considered, with mean DMFT among 18- to 20-year-old ABC study participants being 1.7 times that of similarly aged adults at a national level. Most of this disparity was constituted by the decayed component, with ABC study participants having eight times the mean DT of their national-level counterparts. The findings indicate that Aboriginal young adults in this birth cohort experience a disproportionate amount of dental disease relative to their non-indigenous counterparts, and that this pattern is consistent across the life course.

Dental caries risk indicators among Australian Aboriginal young adults.

OBJECTIVES: To determine dental caries risk indicators among a birth cohort of Australian Aboriginal young adults (n=442). METHODS: Data were from the Aboriginal Birth Cohort study, a prospective longitudinal investigation of Aboriginal individuals born 1987-1990 at an Australian regional hospital. Models representing demographic, socioeconomic, behavioural, dental service utilization and clinical oral health variables were tested using multivariate regression. RESULTS: The percent DT>0 was 72.9 (95% CI 68.7-77.1), mean DT was 4.19 (95% CI 3.8-4.6), percent DMFT>0 was 77.4 (95% CI 73.5-81.3) and mean DMFT was 4.84 (95% CI 4.4-5.3). After controlling for other covariates, risk indicators for percent DT>0 included soft drink consumption every day or a few times a week (PR 1.25, 95% CI 1.08-1.45), not consuming milk every day or a few times a week (PR 1.16, 95% CI 1.04-1.30) and sweet consumption every day or a few times a week (PR 1.18, 95% CI 1.04-1.33). Risk indicators for mean DT included sweet consumption every day or a few times a week (B=1.14, 95% CI 0.27-2.02), nonownership of a toothbrush (B=0.91, 95% CI 0.10-1.87) and presence of plaque (B=2.46, 95% CI 0.96-3.96). Those with 4 + occupants in their house the previous night had 1.2 times the prevalence of having DMFT>0 than their counterparts with less household occupants (95% CI 1.01-1.49). Percent DMFT>0 was also associated with consumption of soft drink every day or a few times a week (PR 1.18, 95% CI 1.04-1.34) and consumption of sweets every day or a few times a week (PR 1.23, 95% CI 1.10-1.37). Mean DMFT was higher among those who consumed sweets every day or a few times a week (B = 0.13, 95% CI 0.05-0.22) and who had dental anxiety (B=0.10, 95% CI 0.01-0.19). CONCLUSIONS: In an Australian Aboriginal young adult cohort, risk indicators for dental caries included social determinants such as household size, dietary behaviours such as regular consumption of soft drink and sweets, dental behaviour such as nonownership of a toothbrush and dental anxiety.

Birth size of Australian aboriginal babies.

OBJECTIVES: (i) To describe birth size of Aboriginal babies by sex, gestational age, and Aboriginality; (ii) to analyse the results with reference to standards of ponderal index and birthweight for gestational age. SUBJECTS: 570 liveborn singletons routinely delivered at Royal Darwin Hospital between January 1987 and March 1991, and recorded in the Delivery Suite Register as being born to an Aboriginal mother. MAIN OUTCOME MEASURES: Weight, length and head circumference at birth. RESULTS: The mean birthweight was 3098 g (standard deviation, 601 g), peak gestational age was 39 weeks, 13% were low birthweight and 7% were preterm. Preterm rates did not differ significantly for sex and Aboriginality. Babies without a non-Aboriginal ancestor had a lower mean birthweight and at term, were significantly smaller than babies with a non-Aboriginal ancestor as assessed by mean birthweight, length, head circumference and ponderal index. More than a quarter of babies (27%) without a non-Aboriginal ancestor were below the 10th percentile of birthweight for gestational age, compared with 14.2% of babies with a non-Aboriginal ancestor. CONCLUSIONS: On the basis of postnatal clinical estimates of gestational age, Aboriginal babies have a preterm rate of 7% and Aboriginal babies without a non-Aboriginal ancestor are smaller in size at birth than babies with a non-Aboriginal ancestor.

Reduction in plasma or skin alpha-tocopherol concentration with long-term oral administration of beta-carotene in humans and mice.

BACKGROUND: Beta-carotene is one of the most commonly used compounds in clinical trials of chemopreventive agents in various neoplastic diseases. Animal studies, including our own, have documented that dietary beta-carotene can reduce plasma alpha-tocopherol (vitamin E) levels, but few published studies have examined the clinical or pharmacokinetic ramifications of long-term, high-dose beta-carotene regimens on other fat-soluble vitamins such as alpha-tocopherol. PURPOSE: This study was designed to determine the effects of long-term beta-carotene supplementation on plasma concentrations of alpha-tocopherol in normal human subjects and in an experimental C3H/HeN mouse model. METHODS: In a double-blind study, 45 normal subjects were randomly assigned to receive 0 (placebo), 15, 30, 45, or 60 mg of oral beta-carotene daily for approximately 9 months. Monthly plasma samples were collected. Thirty-five C3H/HeN mice were fed a basal diet with or without beta-carotene and treated topically with or without alpha-tocopherol, except for the control mice, which received UV radiation for 27 weeks from week 3 to week 30. Plasma and dorsal skin samples were taken after 40 weeks and were analyzed for alpha-tocopherol and/or beta-carotene by high-performance liquid chromatography. RESULTS: Long-term dietary beta-carotene administration resulted in statistically significant reductions in levels of alpha-tocopherol in the skin and plasma of UV-irradiated mice. In the human study, the decrease in plasma alpha-tocopherol levels was progressive and significant between 6 and 9 months of beta-carotene dosing in all dosage groups. The greatest decrease was observed during the 9th (last) month of dosing, with a decrease of 40% from baseline. All oral beta-carotene doses (15-60 mg/d), however, resulted in similar decreases in steady-state plasma levels of alpha-tocopherol and in only small differences in beta-carotene plasma levels. CONCLUSION: Long-term oral administration of beta-carotene decreased steady-state plasma concentrations of alpha-tocopherol. The lack of a significant dose-response effect between doses of beta-carotene and alpha-tocopherol plasma levels is not unexpected, given the small differences in steady-state beta-carotene plasma levels in the four beta-carotene dose groups. IMPLICATIONS: Studies are needed to determine how long-term beta-carotene dosing influences tissue distribution of dietary alpha-tocopherol. Careful surveillance for this and other potentially harmful nutrient interactions should become part of all long-term intervention studies.

An evaluation of three methods used to assess the gestational age of aboriginal neonates.

Many Aboriginal women do not recall their last menstrual period date, so alternative methods of estimating gestational age are necessary for optimal obstetric and neonatal care. In this retrospective review of 605 Aboriginal infants born at the Royal Darwin Hospital, the gestational age was estimated by the Dubowitz method and compared with available gestational age estimates from first fundal height and first ultrasound measurement. There was good agreement between the Dubowitz and ultrasound estimates of gestational age with best agreement occurring when ultrasound was done in the first trimester and worst agreement in the third trimester. Agreement between fundal height and Dubowitz estimates was poor but the measurement of fundal height was not standardized. When accurate last menstrual period information is absent, these findings suggest that good estimates of gestational age in Aboriginal neonates can be determined from the Dubowitz assessment at birth and from ultrasound measurements taken in the first trimester.