High-frequency spectral changes in Dorsolateral Prefrontal Cortex for potential neuoroprosthetics.

Dorsolateral Prefrontal Cortex (DLPFC) has been associated with goal encoding in primates. Thus far, the majority of research involving DLPFC, including all electrophysiology studies, has been performed in non-human primates. In this paper, we explore the possibility of utilizing the cortical activity in DLPFC in humans for use in Brain-Computer Interfaces (BCIs). Electrocorticographic signals were recorded from seven patients with intractable epilepsy who had electrode coverage over DLPFC. These subjects performed a visuomotor target-based task to assess DLPFC's involvement in planning, execution, and accomplishment of the simple motor task. These findings demonstrate that there is a distinct high-frequency spectral component in DLPFC associated with accomplishment of the task. It is envisioned that these signals could potentially provide a novel verification of task accomplishment for a BCI.

Linkage of data in the study of ethnic inequalities and inequities in health outcomes in Scotland, New Zealand and The Netherlands: insights for global study of ethnicity and health.

Reducing inequalities in health is a global priority. An essential tool in achieving this reduction is the ability to provide valid measurements of inequalities, which are comparable over time and ultimately across countries and continents. With valid data a true understanding of inequalities can be ascertained, which can begin to inform effective legislation and policy. In this workshop, the speakers described in three different countries, Scotland, New Zealand and The Netherlands, how record linkage has been used to link ethnic status to health and health care measures and so to determine ethnic inequalities in health with the ultimate aim of reducing these inequalities.

Are neighbourhood social fragmentation and suicide associated in New Zealand? A national multilevel cohort study.

BACKGROUND: Studies of the association between neighbourhood fragmentation and suicide have yielded varied results, and none has simultaneously adjusted for neighbourhood fragmentation, neighbourhood deprivation and individual-level factors. METHOD: A multilevel analysis of a 3-year cohort study was carried out using probabilistic linkage of census and mortality records, and two measures of neighbourhood fragmentation. A total of 2.8 million respondents to the 1996 New Zealand census were followed up for 3 years for mortality (1101 suicide deaths in the analysis), aged from 20 to 74 years at follow-up. RESULTS: No consistent association was observed between either measure of neighbourhood social fragmentation and suicide, after controlling for individual-level confounders and neighbourhood deprivation. There was some evidence of a U-shaped relationship between neighbourhood fragmentation and suicide, especially for the Congdon(NZ) index. There was no evidence of an association for a nine-variable index that captured family-type variables as well as the usual attachment-type variables. Neighbourhood deprivation remained as an important predictor of suicide rates. CONCLUSION: This paper highlights the importance of understanding both the measure and the wider national context when considering neighbourhood effects on suicide.

Inclusion of indigenous and ethnic minority populations in intervention trials: challenges and strategies in a New Zealand supermarket study.

BACKGROUND: The Supermarket Healthy Options Project (SHOP) is a large, randomised, controlled trial designed to evaluate the effect of tailored nutrition education and price discounts on supermarket food purchases. A key objective was to recruit approximately equal numbers of Maori, Pacific and non-Maori, non-Pacific shoppers. This paper describes the recruitment strategies used and evaluates their impact on recruitment of Maori, Pacific and non-Maori, non-Pacific trial participants. METHODS: Trial recruitment strategies included mailed invitations to an electronic register of supermarket customers; in-store targeted recruitment; and community-based recruitment. RESULTS: Of the 1103 total trial randomisations for whom ethnicity was known, 247 (22%) were Maori, 101 (9%) Pacific and 755 (68%) were non-Maori, non-Pacific shoppers. Mailed invitations produced the greatest proportion of randomisations (73% vs 7% in-store, and 20% from community recruitment). However, in-store and community recruitment were essential to boost Maori and Pacific samples. The cost of mailout (NZ$40 (14 pounds) per randomised participant) was considerably less than the cost of community and in-store recruitment (NZ$301 (105 pounds) per randomised participant). CONCLUSIONS: The findings demonstrate considerable challenges and cost in recruiting indigenous and minority ethnic participants into intervention trials. Researchers and funding organisations should allocate more resources to recruitment of indigenous and minority populations than to recruitment of majority populations. Community recruitment and networks appear to be better ways to recruit these populations than passive strategies like mailouts.

What is the association between wealth and mental health?

BACKGROUND: Socioeconomic inequalities in mental health have been shown in a number of populations. This study aims to investigate the association between asset wealth and psychological distress in New Zealand and whether it is independent of other socioeconomic measures and baseline health status. METHODS: Data for this study were from the first three waves of the Survey of Families, Income and Employment (SoFIE) conducted in New Zealand (2002-2004/05) (n = 15 340). The Kessler-10 was used as a measure of psychological distress. The association of quintiles of wealth with psychological distress was investigated using logistic regression, controlling for confounders, socioeconomic variables and prior health status. RESULTS: The odds ratio (OR) of reporting high psychological distress were greater in the lowest wealth quintile compared with the highest (OR 3.06, 95% CI 2.68 to 3.50). Adjusting for age and sex did not alter the relationship; however, adjusting for income and area deprivation attenuated the OR to 1.73 (95% CI 1.48 to 2.04). Further controlling for baseline health status reduced the OR to 1.45 (95% CI 1.23 to 1.71), although the confidence interval still excluded the null. CONCLUSIONS: Inequalities in wealth are strongly associated with psychological distress, over and above other confounding demographic variables and baseline health status. Much, but not all, of that association is confounded by adult socioeconomic position. This suggests that policy measures to improve asset wealth, through savings and home ownership, may have positive health implications and help to reduce health inequalities.

Glossary for econometrics and epidemiology.

Epidemiologists and econometricians are often interested in similar topics-socioeconomic position and health outcomes-but the different languages that epidemiologists and economists use to interpret and discuss their results can create a barrier to mutual communication. This glossary defines key terms used in econometrics and epidemiology to assist in bridging this gap.

The effect of eradicating poverty on childhood unintentional injury mortality in New Zealand: a cohort study with counterfactual modelling.

BACKGROUND: The aim of this study was to examine the effect of household income on unintentional injury mortality in children and to model the potential impact of eradicating income poverty as an injury prevention strategy. METHODS: A national retrospective cohort study linking census to mortality records carried out in New Zealand during a 3-year period following the 1991 census and including children aged 0-14 years on census night. The main outcome measures are odds ratios (ORs) for unintentional injury death by equivalised household income category and proportional reductions (population-attributable risk) in unintentional injury mortality from modelled scenarios of nil poverty. RESULTS: One-third of children lived in households earning less than 60% of the national median household income. Age-adjusted odds of death from unintentional injury were higher for children from any income category compared with the highest, and were most elevated for children from households earning less than 40% of the national median income (OR 2.81, 95% CI 1.73 to 4.55). Adjusting for ethnicity, household education, family status and labour force status halved the effect size (OR 1.83, 1.02 to 3.28). Thirty per cent of injury mortality was attributable to low or middle household income using the highest income category as reference. Altering the income distribution to eradicate poverty, defined by a threshold of 50% or 60% of the national median income, reduced injury mortality in this model by a magnitude of 3.3% to 6.6%. CONCLUSIONS: Household income is related to a child's risk of death from unintentional injury independent of measured confounders. Most deaths attributable to low income occur among households that are not defined as "in poverty". The elimination of poverty may reduce childhood unintentional injury mortality by 3.3% to 6.6%.

The contextual effects of neighbourhood access to supermarkets and convenience stores on individual fruit and vegetable consumption.

BACKGROUND: It is often suggested that neighbourhood access to food retailers affects the dietary patterns of local residents, but this hypothesis has not been adequately researched. We examine the association between neighbourhood accessibility to supermarkets and convenience stores and individuals' consumption of fruit and vegetables in New Zealand. METHODS: Using geographical information systems, travel times from the population-weighted centroid of each neighbourhood to the closest supermarket and convenience store were calculated for 38,350 neighbourhoods. These neighbourhood measures of accessibility were appended to the 2002-3 New Zealand Health Survey of 12,529 adults. RESULTS: The consumption of the recommended daily intake of fruit was not associated with living in a neighbourhood with better access to supermarkets or convenience stores. Similarly, access to supermarkets was not related to vegetable intake. However, individuals in the quartile of neighbourhoods with the best access to convenience stores had 25% (OR 0.75, 95% CI 0.60% to 0.93%) lower odds of eating the recommended vegetable intake compared to individuals in the base category (worst access). CONCLUSION: This study found little evidence that poor locational access to food retail provision is associated with lower fruit and vegetable consumption. However, before rejecting the common sense notion that neighbourhood access to fruit and vegetables affects personal consumption, research that measures fruit and vegetable access more precisely and directly is required.

Cancer is overtaking cardiovascular disease as the main driver of socioeconomic inequalities in mortality: New Zealand (1981-99).

BACKGROUND: Relative socioeconomic disparities in cardiovascular mortality have increased in New Zealand, as in many Western countries in Northern Europe, the US and Australia during the late 20th century. However, substantial declines in cardiovascular mortality mean that its absolute contribution to overall mortality has decreased. RESEARCH QUESTIONS: How did the absolute contribution of major causes of death to socioeconomic inequalities in New Zealand change during the 1980s and 90s? METHODS: Linked census-mortality cohorts were used to calculate the contribution of different causes of death to inequalities in mortality, measured with the slope index of inequality, by household income. RESULTS: Between 1981-4 and 1996-9, the contribution of cardiovascular disease (CVD) to total inequality declined from 55% to 28% among women, whereas at the same time the contribution of cancers increased from 14% to 37%. Among men, the contribution of CVD to total inequality peaked at 47% in 1986-9, then declined to 38% in 1996-9. The contribution of cancer increased from 19% to 26% in men. CONCLUSION: CVD mortality has declined at all income levels and so too has the contribution of CVD to mortality inequalities. Concurrently, the contribution of cancer to inequalities in mortality by income has increased and, in women at least, is now greater than the contribution of CVD. It is hypothesised that a similar crossover is occurring in other populations where CVD mortality has declined, although socioeconomic differences in the distribution and effect of the obesity epidemic for CVD may ensure its continuing importance. Prevention efforts aimed at reducing socioeconomic inequalities in mortality will need to increasingly focus on socioeconomic inequalities in cancer mortality.

Retrofitting houses with insulation to reduce health inequalities: aims and methods of a clustered, randomised community-based trial.

This paper describes the purpose and methods of a single-blinded, clustered and randomised trial of the health impacts of insulating existing houses. The key research question was whether this intervention increased the indoor temperature and lowered the relative humidity, energy consumption and mould growth in the houses, as well as improved the health and well-being of the occupants and thereby lowered their utilisation of health care. Households in which at least one person had symptoms of respiratory disease were recruited from seven predominantly low-income communities in New Zealand. These households were then randomised within communities to receive retrofitted insulation either during or after the study. Measures at baseline (2001) and follow-up (2002) included subjective measures of health, comfort and well-being and objective measures of house condition, temperature, relative humidity, mould (speciation and mass), endotoxin, beta glucans, house dust mite allergens, general practitioner and hospital visits, and energy or fuel usage. All measurements referred to the three coldest winter months, June, July and August. From the 1352 households that were initially recruited, baseline information was obtained from 1310 households and 4413 people. At follow-up, 3312 people and 1110 households remained, an 84% household retention rate and a 75% individual retention rate. Final outcome results will be reported in a subsequent paper. The study showed that large trials of complex environmental interventions can be conducted in a robust manner with high participation rates. Critical success factors are effective community involvement and an intervention that is valued by the participants.

Could mainstream anti-smoking programs increase inequalities in tobacco use? New Zealand data from 1981-96.

OBJECTIVE: To examine changes in the socio-economic and ethnic distribution of smoking in the New Zealand population from 1981 to 1996, and to consider the implication of these data for policies aimed at reducing tobacco consumption. METHODS: Cross-sectional data were taken from 4.7 million respondents to the 1981 and 1996 New Zealand Censuses and 4,619 participants in a 1989 national survey, aged 15 to 79 years. Smoking prevalence rates were calculated by socio-economic position and ethnicity. RESULTS: Smoking prevalence fell in the period 1981-96 in every population group. However, socio-economic and ethnic differences in smoking increased in relative terms. Smoking prevalence ratios comparing the least advantaged with the most advantaged groups increased in men from 1.20 to 1.53 by income, 1.54 to 1.85 by education, and 1.49 to 1.67 by ethnicity. In women, prevalence ratios increased from 1.17 to 1.51 by income, 1.55 to 2.02 by education, and 1.85 to 2.20 by ethnicity. The greatest increase in socio-economic differences may have occurred during the 1980s, the period of greatest overall decline in total population smoking. CONCLUSIONS: Socio-economic and ethnic disparities in New Zealanders' smoking patterns increased during the 1980s and '90s, a period of significant decline in overall smoking prevalence. IMPLICATIONS: Public health programs aimed at reducing tobacco use should pay particular attention to disadvantaged, Indigenous and ethnic minority groups in order to avoid widening relative inequalities in smoking and smoking-related health outcomes.

How much downside? Quantifying the relative harm from tobacco taxation.

OBJECTIVE: To estimate the loss of life expectancy attributable to tobacco taxation (via financial hardship and flow-on health effect) in New Zealand. DESIGN: Data were used on the gradients in life expectancy and smoking by neighbourhood socioeconomic deprivation and survey data on tobacco expenditure. Three estimates were modelled of the percentage of the crude association of neighbourhood deprivation with life expectancy that might be mediated via financial hardship: 100%, 50%, and 25% (best estimate). From this information the impact of tobacco taxation on life expectancy was estimated. MAIN RESULTS: For the total population, the estimated loss of life expectancy due to tobacco tax ranged from 0.005 years to 0.027 years. For people living in the most deprived 30% of neighbourhoods, the range was 0.009 to 0.044 years (that is, 3 to 16 days of lost life expectancy). For the total population the loss of life expectancy attributable to tobacco tax ranged from 119 to 460 times less than that attributable to deprivation. The loss of life expectancy attributable to tobacco tax was 42 to 257 times less than that attributable to smoking. CONCLUSIONS: The estimated harm to life expectancy from tobacco taxation (via financial hardship) is orders of magnitude smaller than the harm from smoking. Although the analyses involve a number of simplistic assumptions, this conclusion is likely to be robust. Policy makers should be reassured that tobacco taxation is likely to be achieving far more benefit than harm in the general population and in socioeconomically deprived populations.

A multilevel analysis of socioeconomic (small area) differences in household food purchasing behaviour.

STUDY OBJECTIVE: To examine the association between area and individual level socioeconomic status (SES) and food purchasing behaviour. DESIGN: The sample comprised 1000 households and 50 small areas. Data were collected by face to face interview (66.4% response rate). SES was measured using a composite area index of disadvantage (mean 1026.8, SD = 95.2) and household income. Purchasing behaviour was scored as continuous indices ranging from 0 to 100 for three food types: fruits (mean 50.5, SD = 17.8), vegetables (61.8, 15.2), and grocery items (51.4, 17.6), with higher scores indicating purchasing patterns more consistent with dietary guideline recommendations. SETTING: Brisbane, Australia, 2000. PARTICIPANTS: Persons responsible for their household's food purchasing. MAIN RESULTS: Controlling for age, gender, and household income, a two standard deviation increase on the area SES measure was associated with a 2.01 unit increase on the fruit purchasing index (95% CI -0.49 to 4.50). The corresponding associations for vegetables and grocery foods were 0.60 (-1.36 to 2.56) and 0.94 (-1.35 to 3.23). Before controlling for household income, significant area level differences were found for each food, suggesting that clustering of household income within areas (a composition effect) accounted for the purchasing variability between them. CONCLUSIONS: Living in a socioeconomically advantaged area was associated with a tendency to purchase healthier food, however, the association was small in magnitude and the 95% CI for area SES included the null. Although urban areas in Brisbane are differentiated on the basis of their socioeconomic characteristics, it seems unlikely that where you live shapes your procurement of food over and above your personal characteristics.

Unemployment and suicide. Evidence for a causal association?

OBJECTIVES: To determine the independent associations of labour force status and socioeconomic position with death by suicide. DESIGN: Cohort study assembled by anonymous and probabilistic record linkage of census and mortality records. PARTICIPANTS: 2.04 million respondents to the New Zealand 1991 census aged 18-64 years. MAIN OUTCOME MEASURE: Suicide in the three years after census night. RESULTS: The age adjusted odds ratios (95% confidence intervals) of death by suicide among 25 to 64 year olds who were unemployed compared with employed were 2.46 (1.10 to 5.49) for women and 2.63 (1.87 to 3.70) for men. Similarly increased odds ratios were observed for the non-active labour force compared with the employed. Strong age only adjusted associations of suicide death with the socioeconomic factors of education (men only), car access, and household income were observed. Compared with those who were married on census night, the non-married had odds ratios of suicide of 1.81 (1.22 to 2.69) for women and 2.08 (1.66 to 2.61) for men. In a multivariable model the association of socioeconomic factors with suicide reduced to the null. However, marital status and labour force status remained strong predictors of suicide death. Unemployment was also strongly associated with suicide death among 18-24 year old men. Sensitivity analyses suggested that confounding by mental illness might explain about half, but not all, of the association between unemployment and suicide. CONCLUSIONS: Being unemployed was associated with a twofold to threefold increased relative risk of death by suicide, compared with being employed. About half of this association might be attributable to confounding by mental illness.

No association of income inequality with adult mortality within New Zealand: a multi-level study of 1.4 million 25-64 year olds.

STUDY OBJECTIVE: To determine the association of regional income inequality within New Zealand with mortality among 25-64 year olds. DESIGN: Individual census and mortality records were linked over the 1991-94 period. Income inequality (Gini coefficients) and average household income variables were calculated for 35 regions. "Individual level" variables were sex, age, ethnicity, household income, rurality, and small area socioeconomic deprivation. Logistic regression was used for the analyses. Sensitivity analyses for the level of regional aggregation were conducted. PARTICIPANTS: 1.4 million New Zealand census respondents aged 25-64 years followed up for mortality for three years. MAIN RESULTS: Controlling for age, ethnicity, rurality, household income, and regional mean income, there was no association of income inequality with all cause mortality for either men (OR=1.007 for a 0.01 increase in the Gini, 95% confidence intervals 0.989 to 1.024) or women (OR=1.004, 0. 983 to 1.026). By cause of death (cancer, cardiovascular disease, unintentional injury, and suicide) there was some suggestion of a positive association for female unintentional injury (OR=1.068, 0.952 to 1.198) and suicide (OR=1.087, 0.957 to 1.234) but the 95% confidence intervals all included 1.0. Failure to control for ethnicity at the individual level resulted in some association of increasing regional income inequality with increasing mortality risk. Using fewer (n=14) or more (n=73) regional divisions did not substantially change the findings. CONCLUSION: There is no convincing evidence of an association of income inequality within New Zealand with adult mortality. Previous ecological analyses within New Zealand suggesting an association of income inequality with mortality were confounded by ethnicity at the individual level. However, this study does not refute the possibility that income inequality at the national level affects health.

What is chronic fatigue syndrome? Heterogeneity within an international multicentre study.

OBJECTIVE: We sought to compare the characteristics of patients presenting with chronic fatigue (CF) and related syndromes in eight international centres and to subclassify these subjects based on symptom profiles. The validity of the subclasses was then tested against clinical data. METHOD: Subjects with a clinical diagnosis of CF completed a 119-item self-report questionnaire to provide clinical symptom data and other information such as illness course and functional impairment. Subclasses were generated using a principal components-like analysis followed by latent profile analysis (LPA). RESULTS: 744 subjects returned complete data sets (mean age 40.8 years, mean length of illness 7.9 years, female to male ratio 3:1). Overall, the subjects had a high rate of reporting typical CF symptoms (fatigue, neuropsychological dysfunction, sleep disturbance). Using LPA, two subclasses were generated. Class one (68% sample) was characterized by: younger age, lower female to male ratio; shorter episode duration; less premorbid, current and familial psychiatric morbidity; and, less functional disability. Class two subjects (32%) had features more consistent with a somatoform illness. There was substantial variation in subclass prevalences between the study centres (Class two range 6-48%). CONCLUSIONS: Criteria-based approaches to the diagnosis of CF and related syndromes do not select a homogeneous patient group. While substratification of patients is essential for further aetiological and treatment research, the basis for allocating such subcategories remains controversial.