Human factors in IVHS: age, driving stress and health.

Arizona Department of Transportation, Phoenix

Carotid artery intimal medial thickness, brachial artery flow-mediated vasodilation and cardiovascular risk factors in diabetic and non-diabetic indigenous Australians

Background: Indigenous Australians are at high risk for cardiovascular disease and type 2 diabetes. Carotid artery intimal medial thickness (CIMT) and brachial artery flow-mediated vasodilation (FMD) are ultrasound imaging based surrogate markers of cardiovascular risk. This study examines the relative contributions of traditional cardiovascular risk factors on CIMT and FMD in adult Indigenous Australians with and without type 2 diabetes mellitus. Method: One hundred and nineteen Indigenous Australians were recruited. Physical and biochemical markers of cardiovascular risk, together with CIMT and FMD were meausred for all subjects. Results: Fifty-three Indigenous Australians subjects (45%) had type 2 diabetes mellitus. There was a significantly greater mean CIMT in diabetic versus non-diabetic subjects (p = 0.049). In the non-diabetic group with non-parametric analyses, there were significant correlations between CIMT and: age (r = 0.64, p < 0.001), systolic blood pressure (r = 0.47, p < 0.001) and non-smokers (r = -0.30, p = 0.018). In the diabetic group, non-parametric analysis showed correlations between CIMT, age (r = 0.36, p = 0.009) and duration of diabetes (r = 0.30, p = 0.035) only. Adjusting forage, sex, smoking and history of cardiovascular disease, Hb(A1c) became the sole significant correlate of CIMT (r = 0.35,p = 0.01) in the diabetic group. In non-parametric analysis, age was the sole significant correlate of FMD (r = -0.31,p = 0.013), and only in non-diabetic subjects. Linear regression analysis showed significant associations between CIMT and age (t = 4.6,p < 0.001), systolic blood pressure (t = 2.6, p = 0.010) and Hb(A1c) (t = 2.6, p = 0.012), smoking (t = 2.1, p = 0.04) and fasting LDL-cholesterol (t = 2.1, p = 0.04). There were no significant associations between FMD and examined cardiovascular risk factors with linear regression analysis Conclusions: CIMT appears to be a useful surrogate marker of cardiovascular risk in this sample of Indigenous Australian subjects, correlating better than FMD with established cardiovascular risk factors. A lifestyle intervention programme may alleviate the burden of cardiovascular disease in Indigenous Australians by reducing central obesity, lowering blood pressure, correcting dyslipidaemia and improving glycaemic control. CIMT may prove to be a useful tool to assess efficacy of such an intervention programme. (c) 2004 Elsevier Ireland Ltd. All rights reserved.

Socioeconomic position, cognitive function, and clustering of cardiovascular risk factors in adolescence: Findings from the Mater University Study of Pregnancy and its outcomes

Objectives: The objectives of this study were to examine the extent of clustering of smoking, high levels of television watching, overweight, and high blood pressure among adolescents and whether this clustering varies by socioeconomic position and Cognitive function. Methods: This study was a cross-sectional analysis of 3613 (1742 females) participants of an Australian birth cohort who were examined at age 14. Results: Three hundred fifty-three (9.8%) of the participants had co-occurrence of three or four risk factors. Risk factors clustered in these adolescents with a greater number of participants than would be predicted by assumptions of independence having no risk factors and three or four risk factors. The extent of clustering tended to be greater in those from lower-income families and among those with lower cognitive function. The age-adjusted ratio of observed to expected cooccurrence of three or four risk factors was 2.70 (95% confidence interval [Cl], 1.80-4.06) among those from low-income families and 1.70 (95% Cl, 1.34-2.16) among those from more affluent families. The ratio among those with low Raven's scores (nonverbal reasoning) was 2.36 (95% Cl, 1.69-3.30) and among those with higher scores was 1.51 (95% Cl, 1.19-1.92); similar results for the WRAT 3 score (reading ability) were 2.69 (95% Cl, 1.85-3.94) and 1.68 (95% Cl, 1.34-2.11). Clustering did not differ by sex. Conclusion: Among adolescents, coronary heart disease risk factors cluster, and there is some evidence that this clustering is greater among those from families with low income and those who have lower cognitive function.

Effect of lutein and antioxidant dietary supplementation on contrast sensitivity in age-related macular disease:A randomized controlled trial

Objective: The aim of the study is to determine the effect of lutein combined with vitamin and mineral supplementation on contrast sensitivity in people with age-related macular disease (ARMD). Design: A prospective, 9-month, double-masked randomized controlled trial. Setting: Aston University, Birmingham, UK and a UK optometric clinical practice. Subjects: Age-related maculopathy (ARM) and atrophic age-related macular degeneration (AMD) participants were randomized (using a random number generator) to either placebo (n = 10) or active (n=15) groups. Three of the placebo group and two of the active group dropped out. Interventions: The active group supplemented daily with 6 mg lutein combined with vitamins and minerals. The outcome measure was contrast sensitivity (CS) measured using the Pelli-Robson chart, for which the study had 80% power at the 5% significance level to detect a change of 0.3log units. Results: The CS score increased by 0.07 ± 0.07 and decreased by 0.02 ± 0.18 log units for the placebo and active groups, respectively. The difference between these values is not statistically significant (z = 0.903, P = 0.376). Conclusion: The results suggest that 6 mg of lutein supplementation in combination with other antioxidants is not beneficial for this group. Further work is required to establish optimum dosage levels.

The effect of lutein and antioxidant dietary supplementation on contrast sensitivity in age-related macular disease

There is interest in the use of nutritional supplementation as a prevention and treatment strategy for age-related macular disease as later stages of the condition are the leading cause of visual disability in the developed World .

A randomised controlled trial investigating the effect of nutritional supplementation on visual function in normal, and age-related macular disease affected eyes:design and methodology [ISRCTN78467674]

Background: Age-related macular disease is the leading cause of blind registration in the developed world. One aetiological hypothesis involves oxidation, and the intrinsic vulnerability of the retina to damage via this process. This has prompted interest in the role of antioxidants, particularly the carotenoids lutein and zeaxanthin, in the prevention and treatment of this eye disease. Methods: The aim of this randomised controlled trial is to determine the effect of a nutritional supplement containing lutein, vitamins A, C and E, zinc, and copper on measures of visual function in people with and without age-related macular disease. Outcome measures are distance and near visual acuity, contrast sensitivity, colour vision, macular visual field, glare recovery, and fundus photography. Randomisation is achieved via a random number generator, and masking achieved by third party coding of the active and placebo containers. Data collection will take place at nine and 18 months, and statistical analysis will employ Student's t test. Discussion: A paucity of treatment modalities for age-related macular disease has prompted research into the development of prevention strategies. A positive effect on normals may be indicative of a role of nutritional supplementation in preventing or delaying onset of the condition. An observed benefit in the age-related macular disease group may indicate a potential role of supplementation in prevention of progression, or even a degree reversal of the visual effects caused by this condition.

Dietary analysis and patterns of nutritional supplement use in normal and age-related macular disease affected subjects:a prospective cross-sectional study

Background: Poor diet is thought to be a risk factor for many diseases, including age-related macular disease (ARMD), which is the leading cause of blind registration in those aged over 60 years in the developed world. The aims of this study were 1) to evaluate the dietary food intake of three subject groups: participants under the age of 50 years without ARMD (U50), participants over the age of 50 years without ARMD (O50), and participants with ARMD (AMD), and 2) to obtain information on nutritional supplement usage. Methods: A prospective cross-sectional study designed in a clinical practice setting. Seventy-four participants were divided into three groups: U50; 20 participants aged < 50 years, from 21 to 40 (mean ± SD, 37.7 ± 10.1 years), O50; 27 participants aged > 50 years, from 52 to 77 (62.7 ± 6.8 years), and ARMD; 27 participants aged > 50 years with ARMD, from 55 to 79 (66.0 ± 5.8 years). Participants were issued with a three-day food diary, and were also asked to provide details of any daily nutritional supplements. The diaries were analysed using FoodBase 2000 software. Data were input by one investigator and statistically analysed using Microsoft Excel for Microsoft Windows XP software, employing unpaired t-tests. Results: Group O50 consumed significantly more vitamin C (t = 3.049, p = 0.005) and significantly more fibre (t = 2.107, p = 0.041) than group U50. Group ARMD consumed significantly more protein (t = 3.487, p = 0.001) and zinc (t = 2.252, p = 0.029) than group O50. The ARMD group consumed the highest percentage of specific ocular health supplements and the U50 group consumed the most multivitamins. Conclusions: We did not detect a deficiency of any specific nutrient in the diets of those with ARMD compared with age- and gender-matched controls. ARMD patients may be aware of research into use of nutritional supplementation to prevent progression of their condition.

Dietary analysis and nutritional behaviour in people with and without age-related macular disease

Background and Aims: Consumption of antioxidant nutrients can reduce the risk of progression of age-related macular degeneration (AMD) - the leading cause of visual impairment in adults over the age of 50 years in the UK. Lutein and zeaxanthin (L&Z) are of particular interest because they are selectively absorbed by the central retina. The objectives of this study were to analyse the dietary intake of a group of AMD patients, assess their ability to prepare and cook healthy food, and to make comparisons with people not affected by AMD. Methods: 158 participants with AMD were recruited via the UK charity The Macular Society, and fifty participants without AMD were recruited from optometric practice. A telephone interview was conducted by trained workers where participants completed a 24 hour food diary, and answered questions about cooking and shopping capabilities. Results: In the AMD group, the average L&Z intake was low in for both males and females. Those able to cook a hot meal consumed significantly more L&Z than those who were not able. Most participants were not consuming the recommended dietary allowance of fibre, calcium, vitamin D and E, and calorific intake was also lower than recommendations for their age-group. The non-AMD group consumed more kilocalories and more nutrients than the AMD group, but the L&Z intake was similar to those with AMD. The main factor that influenced participant’s food choices was personal preference. Conclusion: For an ‘informed’ population, many AMD participants were under-consuming nutrients considered to be useful for their condition. Participants without AMD were more likely to reach recommended daily allowance values for energy and a range of nutrients. It is therefore essential to design more effective dietary education and dissemination methods for people with, and at risk of, AMD.

Lifestyle factors, adiposity and cardiometabolic risk factors in South Asian women living in Scotland

South Asians migrating to the Western world have a 3 to 5-fold higher risk of developing type 2 diabetes and double the risk of cardiovascular disease (CVD) than the background population of White European descent, without exhibiting a proportional higher prevalence of conventional cardiometabolic risk factors. Notably, women of South Asian descent are more likely to be diagnosed with type 2 diabetes as they grow older compared with South Asian men and, in addition, they have lost the cardio-protective effects of being females. Despite South Asian women in Western countries being a high risk group for developing future type 2 diabetes and CVD, they have been largely overlooked. The aims of this thesis were to compare lifestyle factors, body composition and cardiometabolic risk factors in healthy South Asian and European women who reside in Scotland, to examine whether ethnicity modifies the associations between modifiable environmental factors and cardiometabolic risks and to assess whether vascular reactivity is altered by ethnicity or other conventional and novel CVD risks. I conducted a cross-sectional study and recruited 92 women of South Asian and 87 women of White European descent without diagnosed diabetes or CVD. Women on hormone replacement therapy or hormonal contraceptives were excluded too. Age and body mass index (BMI) did not differ between the two ethnic groups. Physical activity was assessed and with self-reported questionnaires and objectively with the use of accelerometers. Cardiorespiratory fitness was quantified with the predicted maximal oxygen uptake (VO2 max) during a submaximal test (Chester step test). Body composition was assessed with skinfolds measured at seven body sites, five body circumferences, measurement of abdominal subcutaneous (SAT) and visceral adipose tissue (VAT) with the use of magnetic resonance imaging (MRI) and liver fat with the use MR spectroscopy. Dietary density was assessed with food frequency questionnaires. Vascular response was assessed by measuring the response to acetylcholine and sodium nitroprusside with the use of Laser Doppler Imaging with Iontophoresis (LDI-ION) and the response to shear stress with the use of Peripheral Arterial Tonometry (EndoPAT). The South Asian women exhibited a metabolic profile consistent with the insulin resistant phenotype, characterised by greater levels of fasting insulin, lower levels of high density lipoprotein (HDL) and higher levels of triglycerides (TG) compared with their European counterparts. In addition, the South Asians had greater levels of glycated haemoglobin (HbA1c) for any given level of fasting glucose. The South Asian women engaged less time weekly with moderate to vigorous physical activity (MVPA) and had lower levels of cardiorespiratory fitness for any given level of physical activity than the women of White descent. In addition, they accumulated more fat centrally for any given BMI. Notably, the South Asians had equivalent SAT with the European women but greater VAT and hepatic fat for any given BMI. Dietary density did not differ among the groups. Increasing central adiposity had the largest effect on insulin resistance in both ethic groups compared with physical inactivity or decreased cardiorespiratory fitness. Interestingly, ethnicity modified the association between central adiposity and insulin resistance index with a similar increase in central adiposity having a substantially larger effect on insulin resistance index in the South Asian women than in the Europeans. I subsequently examined whether ethnic specific thresholds are required for lifestyle modifications and demonstrated that South Asian women need to engage with MVPA for around 195 min.week-1 in order to equate their cardiometabolic risk with that of the Europeans exercising 150 min.week-1. In addition, lower thresholds of abdominal adiposity and BMI should apply for the South Asians compared with the conventional thresholds. Although the South Asians displayed an adverse metabolic profile, vascular reactivity measured with both methods did not differ among the two groups. An additional finding was that menopausal women with hot flushing of both ethnic groups showed a paradoxical vascular profile with enhanced skin perfusion (measured with LDI-ION) but decreased reactive hyperaemia index (measured with EndoPAT) compared with asymptomatic menopausal women. The latter association was independent of conventional CVD risk factors. To conclude, South Asian women without overt disease who live in Scotland display an adverse metabolic profile with steeper associations between lifestyle risk factors and adverse cardiometabolic outcomes compared with their White counterparts. Further work in exploring ethnic specific thresholds in lifestyle interventions or in disease diagnosis is warranted.