The older people, omega-3, and cognitive health (EPOCH) trial design and methodology: A randomised, double-blind, controlled trial investigating the effect of long-chain omega-3 fatty acids on cognitive ageing and wellbeing in cognitively healthy older adults

Extent: 18p.Background: Some studies have suggested an association between omega-3 long-chain polyunsaturated fatty acids (n-3 LC PUFAs) and better cognitive outcomes in older adults. To date, only two randomised, controlled trials have assessed the effect of n-3 LC PUFA supplementation on cognitive function in older cognitively healthy populations. Of these trials only one found a benefit, in the subgroup carrying the ApoE-ε4 allele. The benefits of n-3 LC PUFA supplementation on cognitive function in older normal populations thus still remain unclear. The main objective of the current study was to provide a comprehensive assessment of the potential of n-3 LC PUFAs to slow cognitive decline in normal elderly people, and included ApoE-ε4 allele carriage as a potential moderating factor. The detailed methodology of the trial is reported herein. Methods: The study was a parallel, 18-month, randomised, double-blind, placebo-controlled intervention with assessment at baseline and repeated 6-monthly. Participants (N = 391, 53.7% female) aged 65-90 years, English-speaking and with normal cognitive function, were recruited from metropolitan Adelaide, South Australia. Participants in the intervention arm received capsules containing fish-oil at a daily dosage of 1720 mg of docosahexaenoic acid and 600 mg of eicosapentaenoic acid while the placebo arm received the equivalent amount of olive oil in their capsules. The primary outcome is rate of change in cognitive performance, as measured by latent variables for the cognitive constructs (encompassing Reasoning, Working Memory, Short-term Memory, Retrieval Fluency, Inhibition, Simple and Choice-Reaction Time, Perceptual Speed, Odd-man-out Reaction Time, Speed of Memory Scanning, and Psychomotor Speed) and assessed by latent growth curve modeling. Secondary outcomes are change in the Mini-mental State Examination, functional capacity and well-being (including health status, depression, mood, and self-report cognitive functioning), blood pressure, and biomarkers of n-3 LC PUFA status, glucose, lipid metabolism, inflammation, oxidative stress, and DNA damage.Vanessa Danthiir, Nicholas R Burns, Ted Nettelbeck, Carlene Wilson and Gary Witter

Subjective well-being in older adults: folate and vitamin B₁₂ independently predict positive affect

Vitamin B₁₂, folate and homocysteine have long been implicated in mental illness, and growing evidence suggests that they may play a role in positive mental health. Elucidation of these relationships is confounded due to the dependence of homocysteine on available levels of vitamin B₁₂ and folate. Cross-sectional and longitudinal relationships between vitamin B₁₂, folate, homocysteine and subjective well-being were assessed in a sample of 391 older, community-living adults without clinically diagnosed depression. Levels of vitamin B₁₂, but not folate, influenced homocysteine levels 18 months later. Vitamin B₁₂, folate and their interaction significantly predicted levels of positive affect (PA) 18 months later, but had no impact on the levels of negative affect or life satisfaction. Cross-sectional relationships between homocysteine and PA were completely attenuated in the longitudinal analyses, suggesting that the cross-sectional relationship is driven by the dependence of homocysteine on vitamin B₁₂ and folate. This is the first study to offer some evidence of a causal link between levels of folate and vitamin B₁₂ on PA in a large, non-clinical population.Laura C. Edney, Nicholas R. Burns and Vanessa Danthii

Retrospective lifetime dietary patterns predict cognitive performance in community-dwelling older Australians

Dietary intake is a modifiable exposure that may have an impact on cognitive outcomes in older age. The long-term aetiology of cognitive decline and dementia, however, suggests that the relevance of dietary intake extends across the lifetime. In the present study, we tested whether retrospective dietary patterns from the life periods of childhood, early adulthood, adulthood and middle age predicted cognitive performance in a cognitively healthy sample of 352 older Australian adults >65 years. Participants completed the Lifetime Diet Questionnaire and a battery of cognitive tests designed to comprehensively assess multiple cognitive domains. In separate regression models, lifetime dietary patterns were the predictors of cognitive factor scores representing ten constructs derived by confirmatory factor analysis of the cognitive test battery. All regression models were progressively adjusted for the potential confounders of current diet, age, sex, years of education, English as native language, smoking history, income level, apoE ɛ4 status, physical activity, other past dietary patterns and health-related variables. In the adjusted models, lifetime dietary patterns predicted cognitive performance in this sample of older adults. In models additionally adjusted for intake from the other life periods and mechanistic health-related variables, dietary patterns from the childhood period alone reached significance. Higher consumption of the 'coffee and high-sugar, high-fat extras' pattern predicted poorer performance on simple/choice reaction time, working memory, retrieval fluency, short-term memory and reasoning. The 'vegetable and non-processed' pattern negatively predicted simple/choice reaction time, and the 'traditional Australian' pattern positively predicted perceptual speed and retrieval fluency. Identifying early-life dietary antecedents of older-age cognitive performance contributes to formulating strategies for delaying or preventing cognitive decline.Diane E. Hosking, Ted Nettelbeck, Carlene Wilson, and Vanessa Danthii

Perceptual underconfidence: a conceptual illusion?

Experimental interest in human decision making has been fertile in the past two decades. It is generally recognized that answers to questions involving general knowledge tend to produce overconfidence, whereas responses to perceptual tasks often result in underconfidence. While experimental psychologists debated the relative merits of single or dual explanations of these phenomena, differential psychologists suggested that confidence is a trait: Some people have high confidence and others express the opposite, no matter what type of task is undertaken. The current study examined these different perspectives using two complex cognitive and nine perceptual discrimination tasks from different sensory modalities. Findings suggest that underconfidence does not generalize across the perceptual domain, indicating that a more complex account of the miscalibration effect is needed. Such an account should incorporate both task characteristics and individual differences to produce a satisfactory psychological explanation of miscalibration. This point is highlighted by the presence of a strong confidence factor that has loadings from confidence ratings from diverse perceptual and cognitive tasks employed in this study. Lazar Stankov, Gerry Pallier, Vanessa Danthiir and Suzanne Moron

Development and preliminary validation of the Toddler Snack Food Feeding Questionnaire

This study describes the development of a measure of parental influences on toddlers' intake of snack foods, the Toddler Snack Food Feeding Questionnaire (TSFFQ), and presents evidence for the factor structure, test-retest reliability, convergent, discriminant and concurrent validity of the instrument. Exploratory factor analysis (EFA) was conducted in two samples (parents of toddlers stating current practices; parents of preschoolers recalling past practices). EFA identified five meaningful and interpretable factors: Rules, Flexibility, Allow Access, Self-efficacy and Child's Attraction. Allow Access, Flexibility, and Child's Attraction were positively correlated with frequency of toddlers' snack food consumption. In the preschool sample only, not-overweight and overweight parents both had significantly lower scores than obese parents on Allow Access. No significant correlations were found between parents' recall of past feeding and BMI z-scores at preschool age. The TSFFQ strengthens our understanding of how parents control their children's intake of snack foods and could be used along with other measures of parental feeding control to investigate parental influences on children's eating behaviour, food preferences, energy balance and weight status.Nadia Corsini, Carlene Wilson, Lisa Kettler and Vanessa Danthii

Factor structure and psychometric properties of the Child Feeding Questionnaire in Australian preschool children

The Child Feeding Questionnaire (CFQ) is a widely used measure of parental feeding practices, comprising seven factors that measure aspects of parental control over feeding and beliefs about children's obesity proneness. Parents in South Australia (N=203) completed the CFQ at their 4- or 5-year-old child's preschool health visits in May and June 2006. This study examined the factor structure and psychometric properties of the questionnaire. Initially, exploratory factor analysis (EFA) was used to examine the factor structure of the CFQ. Using EFA an additional factor could be extracted, comprising 2 items from the Restriction subscale regarding parents' use of food to reward behaviour. Several modified seven factor models of the CFQ, specified in previous research, were examined using confirmatory factor analysis and compared with an eight factor model. An eight factor model specifying an additional factor, food as reward, provided the best fit to the data, however, until replicated and validated, a seven factor model excluding the reward items is recommended for general use. The findings suggest that further work is required in the conceptualization of the Restriction subscale.Nadia Corsini, Vanessa Danthiir, Lisa Kettler and Carlene Wilso

Speeded paper-pencil sustained attention and mental speed tests: Can performances be discriminated?

Mental speed (MS) and sustained attention (SA) are theoretically distinct constructs. However, tests of MS are very similar to SA tests that use time pressure as an impeding condition. The performance in such tasks largely relies on the participants’ speed of task processing (i.e., how quickly and correctly one can perform the simple cognitive tasks). The present study examined whether SA and MS are empirically the same or different constructs. To this end, 24 paper-pencil and computerized tests were administered to 199 students. SA turned out to be highly related to MS task classes: substitution and perceptual speed. Furthermore, SA showed a very close relationship with the paper-pencil MS factor. The correlation between SA and computerized speed was considerably lower but still high. In a higher-order general speed factor model, SA had the highest loading on the higher-order factor; the higher-order factor explained 88% of SA variance. It is argued that SA (as operationalized with tests using time pressure as an impeding condition) and MS cannot be differentiated, at the level of broad constructs. Implications for neuropsychological assessment and future research are discussed. Stefan Krumm, Lothar Schmidt-Atzert, Kurt Michalczyk, and Vanessa Danthii