Keith Dear

Sun exposure and vitamin D are independent risk factors for CNS demyelination

Objectives: To examine whether past and recent sun exposure and vitamin D status (serum 25-hydroxyvitamin D [25(OH)D] levels) are associated with risk of first demyelinating events (FDEs) and to evaluate the contribution of these factors to the latitudinal gradient in FDE incidence in Australia. Methods: This was a multicenter incident case-control study. Cases (n = 216) were aged 18–59 years with a FDE and resident within one of 4 Australian centers (from latitudes 27°S to 43°S), from November 1, 2003, to December 31, 2006. Controls (n = 395) were matched to cases on age, sex, and study region, without CNS demyelination. Exposures measured included self-reported sun exposure by life stage, objective measures of skin phenotype and actinic damage, and vitamin D status. Results: Higher levels of past, recent, and accumulated leisure-time sun exposure were each associated with reduced risk of FDE, e.g., accumulated leisure-time sun exposure (age 6 years to current), adjusted odds ratio (AOR) = 0.70 (95% confidence interval [CI] 0.53–0.94) for each ultraviolet (UV) dose increment of 1,000 kJ/m2 (range 508–6,397 kJ/m2). Higher actinic skin damage (AOR = 0.39 [95% CI 0.17–0.92], highest grade vs the lowest) and higher serum vitamin D status (AOR = 0.93 [95% CI 0.86–1.00] per 10 nmol/L increase in 25(OH)D) were independently associated with decreased FDE risk. Differences in leisure-time sun exposure, serum 25(OH)D level, and skin type additively accounted for a 32.4% increase in FDE incidence from the low to high latitude regions. Conclusions: Sun exposure and vitamin D status may have independent roles in the risk of CNS demyelination. Both will need to be evaluated in clinical trials for multiple sclerosis prevention.

Chronic Arsenic Exposure and Adverse Pregnancy Outcomes in Bangladesh

Background: Chronic exposure to arsenic through drinking water has the potential to cause adverse pregnancy outcomes, although the association has not been demonstrated conclusively. This cross-sectional study assessed the association between arsenic in drinking water and spontaneous abortion, stillbirth, and neonatal death. Methods: In this cross-sectional study, 533 women were interviewed. Information on sociodemographic characteristics, drinking water use, and adverse pregnancy outcomes was obtained through a structured pretested interviewer-administered questionnaire. The respondents reported use of a total of 223 tube wells; for 208 wells, water samples were measured using an ultraviolet/visible spectrophotometry method, whereas 15 were measured by flow-injection hydride generation atomic absorption spectrometry (FIHG-AAS). Results: Excess risks for spontaneous abortion and stillbirth were observed among the participants chronically exposed to higher concentrations of arsenic in drinking water after adjusting for participants height, history of hypertension and diabetes, and (for neonatal death only) age at first pregnancy. Comparing exposure to arsenic concentration of greater than 50 μg/L with 50 μg/L or less, the odds ratios were 2.5 (95% confidence interval = 1.5–4.3) for spontaneous abortion, 2.5 (1.3–4.9) for stillbirth, and 1.8 (0.9–3.6) for neonatal death. Conclusions: These study findings suggest that chronic arsenic exposure may increase the risk of fetal and infant death.

Age group differences in psychological distress: the role of psychosocial risk factors that vary with age.

BACKGROUND There is continuing controversy about how age affects depression and anxiety, with a lack of consistent results across studies. Two reasons for this inconsistency are age bias in measures and different patterns of exposure to risk factors across age groups in various studies. METHOD Data on anxiety and depression symptoms were collected in a community survey of 7485 persons aged 20-24, 40-44 or 60-64 years. These measures were investigated for factorial invariance across age groups. Data were also collected on a wide range of potential risk factors, including social, physical health and personal factors, with the aim of determining whether these factors might partly or wholly account for age group differences. RESULTS The invariance of correlated latent factors representing anxiety and depression was examined across age groups, and a generalized measure of psychological distress was computed. Depression, anxiety and psychological distress showed a decline across age groups for females and a decline from 40-44 to 60-64 years for males. Some of these age differences were accounted for by other risk factors, with the most important being recent crises at work and negative social relationships with family and friends. CONCLUSION Psychological distress generally declined across the age range 20-64 years and this was not attributable to measurement bias. Differential exposure to risk factors explained some, but not all, of the age group difference. Therefore other mechanisms that explain the lower level of distress in older age groups remain to be identified.

Characteristics of childhood peanut allergy in the Australian Capital Territory, 1995 to 2007.

BACKGROUND It is unknown whether clinical features of peanut allergy have changed in the past decade alongside possible increasing prevalence. OBJECTIVE The clinical features of peanut allergy over 13 years were examined with regard to age of onset, sex distribution, severity, and incidence. METHODS Retrospective study of 778 patients (age 4 months to 66 years) diagnosed with peanut allergy at a community-based specialist allergy practice in the Australian Capital Territory. RESULTS Most peanut allergy (90%) developed by age 72 months. In this group, there were no significant time-dependent changes in sex distribution, reaction severity, or age of first reaction (mean/median 12/15.1 months). Later age of first reaction was associated with an increased risk of anaphylaxis in the overall population (P < .01) and in those with onset by 72 months, in whom risk increased by 22.7% (CI, 3.3-45.7) for every additional year of age (P < .02). Asthma was associated with increased risk of anaphylaxis (odds ratio, 1.9; P < .001). In children with peanut allergy, 22% experienced anaphylaxis with first exposure and 30% with anaphylaxis had preceding milder reactions. The estimated minimum incidences of peanut allergy and sensitization by age 72 months for children born in the Australian Capital Territory in 2004 were 1.15% and 1.53%, respectively (by end December 2007), compared with 0.73% and 0.84% for those born in 2001. CONCLUSION Although most characteristics of peanut allergy have changed little over the period of the last 13 years (onset age, sex, comorbidity, severity), later onset was associated with greater risk of anaphylaxis. Our data are consistent with a rise in incidence.

The health impacts of cold homes and fuel poverty

Three reasons to act: the health burden, inequity, and mitigation

The Effects of Extreme Heat on Human Mortality and Morbidity in Australia: Implications for Public Health

Most regions of Australia are exposed to hot summers and regular extreme heat events; and numerous studies have associated high ambient temperatures with adverse health outcomes in Australian cities. Extreme environmental heat can trigger the onset of acute conditions, including heat stroke and dehydration, as well as exacerbate a range of underlying illnesses. Consequently, in the absence of adaptation, the associated mortality and morbidity are expected to increase in a warming climate, particularly within the vulnerable populations of the elderly, children, those with chronic diseases, and people engaged in physical labour in noncooled environments. There is a need for further research to address the evidence needs of public health agencies in Australia. Building resilience to extreme heat events, especially for the most vulnerable groups, is a priority. Public health professionals and executives need to be aware of the very real and urgent need to act now.

White matter hyperintensities and within-person variability in community-dwelling adults aged 60-64 years.

Estimates of white matter hyperintensities (WMH) derived from T2-weighted MRI were investigated in relation to cognitive performance in 469 healthy community-dwelling adults aged 60-64 years. Frontal lobe WMH but not WMH from other brain regions (temporal, parietal, and occipital lobes, anterior and posterior horn, periventricular body) were associated with elevated within-person reaction time (RT) variability (trial to trial fluctuations in RT performance) but not performance on several other cognitive tasks including psychomotor speed, memory, and global cognition. The findings are consistent with the view that elevated within-person variability is related to neurobiological disturbance, and that attentional mechanisms supported by the frontal cortex play a key role in this type of variability.

Association between nutritional status and arsenicosis due to chronic arsenic exposure in Bangladesh.

The role of nutritional factors in arsenic metabolism and toxicity is not clear. Provision of certain low protein diets resulted in decreased excretion of DMA and increased tissue retention of arsenic in experimental studies. This paper reports a prevalence comparison study conducted in Bangladesh to assess the nutritional status among the chronic arsenic exposed and unexposed population. 138 exposed individuals diagnosed as arsenicosis patients were selected from three known arsenic endemic villages of Bangladesh and age, sex matched 144 unexposed subjects were randomly selected from three arsenic free villages. The mean arsenic concentration in drinking water for the exposed and unexposed population was 641.15 and 13.5 μg L−1 respectively. Body Mass Index was found to be lower than 18.5, the cut off point for malnutrition, in 57 (41.31%) out of 138 exposed arsenicosis cases and 31 (21.53%) out of 144 unexposed individuals. The crude prevalence ratio (or risk) was 1.92 (95% CI = 1.33 – 2.78) for poor nutritional status among the arsenicosis cases compared to the unexposed population. The findings of this study add to the evidence that poor nutritional status may increase an individuals susceptibility to chronic arsenic toxicity, or alternatively that arsenicosis may contribute to poor nutritional status.

Offspring number, pregnancy, and risk of a first clinical demyelinating event The AusImmune Study

Objective: To examine the association between past pregnancy, offspring number, and first clinical demyelination risk. Methods: Cases (n = 282) were aged 18–59 years with a first clinical diagnosis of CNS demyelination (first clinical demyelinating event [FCD]) and resident within 1 of 4 Australian centers (from latitudes 27° south to 43° south) from 2003 to 2006. Controls (n = 542) were matched to cases on age, sex, and study region, without first clinical diagnosis of CNS demyelination. Results: Higher offspring number was associated with FCD risk among women (p < 0.001) but not men (p = 0.71); difference in effect; p = 0.001. Among women, higher parity was associated with reduced risk of FCD (adjusted odds ratio 0.51 [95% confidence interval 0.36, 0.72] per birth) with a similar magnitude of effect observed among classic first demyelinating events (adjusted odds ratio 0.47 [95% confidence interval 0.29, 0.74]). The apparent beneficial effect of higher parity was also evident among parous women only (p < 0.001). Among cases, a clear female excess was evident for those with low but not high (4 or more) offspring number. Factors such as human leukocyte antigen DR15 genotype did not appear to modify the association between higher parity and a reduced FCD risk among women. Conclusions: These findings are consistent with a cumulative beneficial effect of pregnancy. Temporal changes toward an older maternal age of parturition and reduced offspring number may partly underlie the increasing female excess among MS cases over time.

Biomarkers, health, lifestyle, and demographic variables as correlates of reaction time performance in early, middle, and late adulthood

We aimed to identify demographic, health, and biomarker correlates of reaction time performance and to determine whether biomarkers explained age differences in reaction time performance. The sample comprised three representative cohorts aged 20–24, 40–44, and 60–64 years, including a total of 7,485 participants. Reaction time measures of intraindividual variability and latency were used. The measure of intraindividual variability used was independent of mean reaction time. Older adults were more variable than younger adults in choice reaction time performance but not simple reaction time performance. The most important correlates of reaction time performance after gender and education were biological markers such as forced expiratory volume at one second, grip strength, and vision. Few measures of physical or mental health or lifestyle were associated with poorer performance on reaction time measures. Biomarkers explained the majority of age-related variance in simple reaction time and a large proportion of variance in choice reaction time. We conclude that for the ages studied, biomarkers are more important than health factors for explaining age differences in reaction time performance.