Melbourne Institute of Applied Economic and Social Research - Research Publications
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ItemWestern diet is associated with a smaller hippocampus: a longitudinal investigation(BMC, 2015-09-08)BACKGROUND: Recent meta-analyses confirm a relationship between diet quality and both depression and cognitive health in adults. While the biological pathways that underpin these relationships are likely multitudinous, extensive evidence from animal studies points to the involvement of the hippocampus. The aim of this study was to examine the association between dietary patterns and hippocampal volume in humans, and to assess whether diet was associated with differential rates of hippocampal atrophy over time. METHODS: Data were drawn from the Personality and Total Health Through Life Study and focused on a subsample of the cohort (n = 255) who were aged 60-64 years at baseline in 2001, completed a food frequency questionnaire, and underwent two magnetic resonance imaging scans approximately 4 years apart. Longitudinal generalized estimating equation linear regression models were used to assess the association between dietary factors and left and right hippocampal volumes over time. RESULTS: Every one standard deviation increase in healthy "prudent" dietary pattern was associated with a 45.7 mm(3) (standard error 22.9 mm(3)) larger left hippocampal volume, while higher consumption of an unhealthy "Western" dietary pattern was (independently) associated with a 52.6 mm(3) (SE 26.6 mm(3)) smaller left hippocampal volume. These relationships were independent of covariates including age, gender, education, labour-force status, depressive symptoms and medication, physical activity, smoking, hypertension and diabetes. While hippocampal volume declined over time, there was no evidence that dietary patterns influenced this decline. No relationships were observed between dietary patterns and right hippocampal volume. CONCLUSIONS: Lower intakes of nutrient-dense foods and higher intakes of unhealthy foods are each independently associated with smaller left hippocampal volume. To our knowledge, this is the first human study to demonstrate associations between diet and hippocampal volume concordant with data previously observed in animal models.
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ItemLongitudinal cohort study describing persistent frequent attenders in Australian primary healthcare(BMJ PUBLISHING GROUP, 2015)OBJECTIVES: To describe patterns of frequent attendance in Australian primary care, and identify the prospective risk factors for persistent frequent attendance. DESIGN, SETTING AND PARTICIPANTS: This study draws on data from the Personality and Total Health (PATH) Through Life Project, a representative community cohort study of residents from the Canberra region of Australia. Participants were assessed on 3 occasions over 8 years. The survey assessed respondents' experience of chronic physical conditions, self-reported health, symptoms of common mental disorders, personality, life events, sociodemographic characteristics and self-reported medication use. A balanced sample was used in analysis, comprising 1734 respondents with 3 waves of data. The survey data for each respondent were individually linked to their administrative health service use data which were used to generate an objective measure of general practitioner (GP) consultations in the 12 months surrounding their interview date. MAIN OUTCOME MEASURES: Respondents in the (approximate) highest decile of attenders on number of GP consultations over a 12-month period at each time point were defined as frequent attenders (FAs). RESULTS: Baseline FAs (8.4%) were responsible for 33.4% of baseline consultations, while persistent FAs (3.6%) for 15.5% of all consultations over the 3 occasions. While there was considerable movement between FA status over time, consistency was greater than expected by chance alone. While there were many factors that differentiated non-FAs from FAs in general, persistent frequent attendance was specifically associated with gender, baseline reports of depression, self-reported physical conditions and disability, and medication use. CONCLUSIONS: The degree of persistence in GP consultations was limited. The findings of this study contribute to our understanding of the risk factors that predict subsequent persistent frequent attendance in primary care. However, further detailed investigation of longitudinal patterns of frequent attendance and consideration of time-varying determinants of frequent attendance is required.
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ItemPatterns of Welfare Attitudes in the Australian Population(PUBLIC LIBRARY SCIENCE, 2015-11-10)The study of community attitudes toward welfare and welfare recipients is an area of increasing interest. This is not only because negative attitudes can lead to stigmatization and discrimination, but because of the relevance of social attitudes to policy decisions. We quantify the attitudes toward welfare in the Australian population using attitude data from a nationally representative survey (N = 3243). Although there was broad support for the social welfare system, negative attitudes are held toward those who receive welfare benefits. Using canonical correlation analysis we identify multivariate associations between welfare attitudes and respondent demographic characteristics. A primary attitudinal dimension of welfare positivity was found amongst those with higher levels of education, life instability, and personal exposure to the welfare system. Other patterns of negative welfare attitudes appeared to be motivated by beliefs that the respondent's personal circumstances indicate their deservingness. Moreover, a previously unidentified and unconsidered subset of respondents was identified. This group had positive attitudes toward receiving government benefits despite having no recent experience of welfare. They did, however, possess many of the characteristics that frequently lead to welfare receipt. These results provide insights into not only how attitudinal patterns segment across the population, but are of relevance to policy makers considering how to align welfare reform with community attitudes.
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ItemThe Prevalence of Mild Cognitive Impairment in Diverse Geographical and Ethnocultural Regions: The COSMIC Collaboration(PUBLIC LIBRARY SCIENCE, 2015-11-05)BACKGROUND: Changes in criteria and differences in populations studied and methodology have produced a wide range of prevalence estimates for mild cognitive impairment (MCI). METHODS: Uniform criteria were applied to harmonized data from 11 studies from USA, Europe, Asia and Australia, and MCI prevalence estimates determined using three separate definitions of cognitive impairment. RESULTS: The published range of MCI prevalence estimates was 5.0%-36.7%. This was reduced with all cognitive impairment definitions: performance in the bottom 6.681% (3.2%-10.8%); Clinical Dementia Rating of 0.5 (1.8%-14.9%); Mini-Mental State Examination score of 24-27 (2.1%-20.7%). Prevalences using the first definition were 5.9% overall, and increased with age (P < .001) but were unaffected by sex or the main races/ethnicities investigated (Whites and Chinese). Not completing high school increased the likelihood of MCI (P ≤ .01). CONCLUSION: Applying uniform criteria to harmonized data greatly reduced the variation in MCI prevalence internationally.
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ItemNo Preview AvailableA method of identifying health-based benchmarks for psychosocial risks at work: A tool for risk assessment(ELSEVIER SCIENCE BV, 2017-03)
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ItemAge-related cognitive decline and associations with sex, education and apolipoprotein E genotype across ethnocultural groups and geographic regions: a collaborative cohort study(PUBLIC LIBRARY SCIENCE, 2017-03)BACKGROUND: The prevalence of dementia varies around the world, potentially contributed to by international differences in rates of age-related cognitive decline. Our primary goal was to investigate how rates of age-related decline in cognitive test performance varied among international cohort studies of cognitive aging. We also determined the extent to which sex, educational attainment, and apolipoprotein E ε4 allele (APOE*4) carrier status were associated with decline. METHODS AND FINDINGS: We harmonized longitudinal data for 14 cohorts from 12 countries (Australia, Brazil, France, Greece, Hong Kong, Italy, Japan, Singapore, Spain, South Korea, United Kingdom, United States), for a total of 42,170 individuals aged 54-105 y (42% male), including 3.3% with dementia at baseline. The studies began between 1989 and 2011, with all but three ongoing, and each had 2-16 assessment waves (median = 3) and a follow-up duration of 2-15 y. We analyzed standardized Mini-Mental State Examination (MMSE) and memory, processing speed, language, and executive functioning test scores using linear mixed models, adjusted for sex and education, and meta-analytic techniques. Performance on all cognitive measures declined with age, with the most rapid rate of change pooled across cohorts a moderate -0.26 standard deviations per decade (SD/decade) (95% confidence interval [CI] [-0.35, -0.16], p < 0.001) for processing speed. Rates of decline accelerated slightly with age, with executive functioning showing the largest additional rate of decline with every further decade of age (-0.07 SD/decade, 95% CI [-0.10, -0.03], p = 0.002). There was a considerable degree of heterogeneity in the associations across cohorts, including a slightly faster decline (p = 0.021) on the MMSE for Asians (-0.20 SD/decade, 95% CI [-0.28, -0.12], p < 0.001) than for whites (-0.09 SD/decade, 95% CI [-0.16, -0.02], p = 0.009). Males declined on the MMSE at a slightly slower rate than females (difference = 0.023 SD/decade, 95% CI [0.011, 0.035], p < 0.001), and every additional year of education was associated with a rate of decline slightly slower for the MMSE (0.004 SD/decade less, 95% CI [0.002, 0.006], p = 0.001), but slightly faster for language (-0.007 SD/decade more, 95% CI [-0.011, -0.003], p = 0.001). APOE*4 carriers declined slightly more rapidly than non-carriers on most cognitive measures, with processing speed showing the greatest difference (-0.08 SD/decade, 95% CI [-0.15, -0.01], p = 0.019). The same overall pattern of results was found when analyses were repeated with baseline dementia cases excluded. We used only one test to represent cognitive domains, and though a prototypical one, we nevertheless urge caution in generalizing the results to domains rather than viewing them as test-specific associations. This study lacked cohorts from Africa, India, and mainland China. CONCLUSIONS: Cognitive performance declined with age, and more rapidly with increasing age, across samples from diverse ethnocultural groups and geographical regions. Associations varied across cohorts, suggesting that different rates of cognitive decline might contribute to the global variation in dementia prevalence. However, the many similarities and consistent associations with education and APOE genotype indicate a need to explore how international differences in associations with other risk factors such as genetics, cardiovascular health, and lifestyle are involved. Future studies should attempt to use multiple tests for each cognitive domain and feature populations from ethnocultural groups and geographical regions for which we lacked data.
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ItemHealth or harm? A cohort study of the importance of job quality in extended workforce participation by older adults(BMC, 2016-08-25)BACKGROUND: As people are living longer, they are being encouraged to work longer. While it is assumed that extended employment will be good for health, the evidence has been mixed. This study considers whether employment and job quality exert an influence on four indicators of health status in older workers. METHODS: Data for this study came from 836 older workers (440 men and 396 women) aged 50-59 years at baseline who participated in the Household, Income and Labour Dynamics in Australia (HILDA) Survey. Using linear regression, we examine within-person change in self-rated, physical and mental health and one health behaviour (physical activity) at two time points over a nine year follow-up period. RESULTS: There were minimal differences in the way health changed for older adults who continued working compared to those who retired voluntarily. However, when we decomposed employment in terms of job quality, health outcomes diverged. Compared to voluntary retirees, older workers who had worked in good quality jobs reported marginally better self-rated health (0.14,-0.02-0.29); but did not differ in their physical (2.31,-1.09-5.72) or mental health (0.51,-1.84-2.87). In contrast, older workers who held poor quality jobs for most of the follow-up period declined in their self-rated (-1.13,-0.28 - -0.02), physical (-4.90, 8.52- - 1.29) and mental health (-4.67, 7.69- - 1.66) relative to voluntary retirees. Older workers who held poor quality jobs for just some of the follow-up period did not differ from voluntary retirees in terms of their health. However there was evidence of a linear relationship between length of exposure to poor quality jobs and decline in health outcomes. CONCLUSION: Extended working lives mean that people will be 'exposed' to work for longer, and this exposure will occur at a life stage characterised by declining health for many. Our findings show that ensuring older workers have access to secure jobs which allow for control over work time, skill use and fair rewards will be essential if policy goals to boost participation and productivity, as well as reduce the health and care costs of the elderly, are to be met.
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ItemThe role of financial hardship, mastery and social support in the association between employment status and depression: results from an Australian longitudinal cohort study(BMJ PUBLISHING GROUP, 2016)OBJECTIVE: There is robust epidemiological and clinical evidence of the harmful effects of unemployment on psychological well-being, but the mechanisms through which this occurs is still strongly debated. In addition, there is even less evidence on the impact of underemployment on mental health. Using longitudinal data collected from a cohort of 20-24 years old, the present study examines a range of employed states and investigates the role of mastery, financial hardship and social support in the relationship between labour status and depression. METHOD: Responses were from the Personality and Total Health (PATH) Through Life Project: A representative, community-based survey conducted in Canberra and Queanbeyan (NSW) in Australia, where respondents (n=2404) in their early twenties were followed for 8 years. Depression was measured using the self-report Goldberg Depression Scale, with the likely presence of depression being indicated by scores 7 or greater. RESULTS: The analyses identified unemployment and underemployment as significant predictors of depression, compared to their employed counterparts. Both unemployment and underemployment remained significantly correlated with depression even after accounting for sociodemographic, economic and psychological variables. Social support, financial hardship and a sense of personal control (mastery) all emerged as important mediators between unemployment and depression. CONCLUSIONS: Both unemployment and underemployment were associated with increased risk of depression. The strength of this relationship was attenuated but remained significant after accounting for key variables (mastery, financial hardship and social support), and extensive sociodemographic and health covariates, indicating that no or inade-quate employment contributes to poorer mental health over and above these factors.
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ItemWithin-person analysis of welfare transitions in a longitudinal panel survey reveals change in mental health service use(OXFORD UNIV PRESS, 2017-12)BACKGROUND: While international research shows that receipt of welfare benefits is associated with poor mental health, less is known about the relationship between welfare receipt and mental health service use. We investigate whether within-person change in welfare recipient status is associated with change in mental health service use. METHODS: Analysis of two waves of data from an Australian national household survey. Random- and fixed-effect models considered the effect of change in welfare receipt status, and assessed whether change in mental health service use differed by type of welfare benefit or the direction of welfare transition. RESULTS: Individuals were more likely to report greater mental health service use at times of welfare receipt. These associations were attenuated, but remained significant, after adjusting for mental health. Increased health service use was not tied to specific types of welfare benefits. The increase in mental health service use associated with a transition onto welfare benefits was much greater than the decline in service use associated with the transition off benefits. CONCLUSIONS: Within individuals, welfare receipt is associated with greater mental health service use. While this does reflect poorer mental health at the time of welfare receipt, other factors seem to facilitate health service use.