An 18-mo randomized, double-blind, placebo-controlled trial of DHA-rich fish oil to prevent age-related cognitive decline in cognitively normal older adults.

Background: Fish oil trials in cognitively healthy older adults have yielded inconsistent results. Supplementation may differentially affect the domains that underpin cognitive performance, and effects may differ across sex or genotype. Objective: The aim of this study was to test whether docosahexaenoic acid (DHA)-rich fish oil slows 18-mo cognitive decline in cognitively healthy elders. Design: In a double-blind, randomized, placebo-controlled, parallel-group trial, cognitively healthy Australian community-dwelling adults (aged 65-90 y) consumed either 1720 mg DHA and 600 mg eicosapentaenoic acid or low-polyphenolic olive oil daily, as capsules, for 18 mo. Groups were allocated by permuted-block randomization and stratified by age. Cognitive assessment was conducted at baseline and then every 6 mo. Primary analyses tested the difference between groups in the rate of 18-mo cognitive change via latent growth curve models on any of the following: reasoning, working memory, short-term memory, retrieval fluency, and cognitive speed-related constructs. Treatment interactions with sex and APOE-ε4 were tested. Secondary outcomes were self-reported changes in well-being and everyday functioning, blood pressure, biomarkers of n-3 (ω-3) long-chain polyunsaturated fatty acids (LC PUFAs), lipids, glucose metabolism, inflammation, oxidative stress, DNA damage, and Mini-Mental State Examination. Results: A total of 403 people were randomly assigned. Data from those who completed baseline were analyzed (n = 390; intervention n = 194, control n = 196). Daily supplementation with 2.3 g DHA-rich fish oil for 18 mo did not maintain or improve cognitive performance. A small negative main effect was found on psychomotor speed (intervention = -0.02, 95% CI: -0.04 to 0.00; d = 0.24, P = 0.03). Treatment effects differed according to sex on retrieval fluency and some speed-based domains, including psychomotor speed, and according to APOE-ε4 carrier status on reaction time and reasoning. For secondary outcomes, treatment was associated with increased perceived cognitive mistakes (d = 0.24; P = 0.003), increased oxidative stress, and expected changes in fatty acid metabolism. Conclusions: Findings do not support supplementing older adults with fish oil to prevent cognitive decline. Treatment interactions with sex and APOE-ε4 carrier status warrant further investigation. This trial was registered at the Australia and New Zealand Clinical Trials Register (ANZCTR) as ACTRN12607000278437.

Parental feeding practices to manage snack food intake: Associations with energy intake regulation in young children.

BACKGROUND: Little attention has been directed to understanding the relationship between restriction and regulation of snack food intake in toddlers. OBJECTIVE: The aim of this study was to examine the effects of parental restriction of toddlers' eating of snacks in the absence of hunger (EAH) and to examine the impact of three contextual factors; snack food access, frequency of snack food consumption, and attraction to snack food. DESIGN: 64 parents and toddlers (aged 22-36 months) took part in a protocol to measure EAH (defined as kJ of energy-dense snack foods consumed). Mean EAH was 199 kJ (SD = 299), with 43 children consuming at least some snacks. Restriction was measured with the Child Feeding Questionnaire Restriction subscale. Snack food access was measured with Allow Access from the Toddler Snack Food Feeding Questionnaire (TSFFQ), snack food consumption was measured with a short snack food frequency questionnaire, and attraction to snack foods was measured with Child's Attraction from the TSFFQ. Moderated regression analyses tested interactions between Restriction and contextual factors in predicting EAH. RESULTS: EAH was associated with Restriction (r = 0.25, p = .05, 95% CI 0.004 - 0.47). There was an interaction between Restriction and accessibility of snack foods (R2 change = 0.08, p = .025); restriction was associated with EAH only when access to snack foods in the home was, on average, higher. The effect of Restriction on EAH was not moderated by frequency of snack food consumption or Child's Attraction. CONCLUSIONS: These finding have practical relevance and reinforce the importance of the home food environment for managing young children's snack food intake.

A randomised-controlled trial of the effects of very low-carbohydrate and high-carbohydrate diets on cognitive performance in patients with type 2 diabetes.

This study compared the longer-term effects of a very low-carbohydrate, high-fat diet with a high-carbohydrate, low-fat diet on cognitive performance in individuals with type 2 diabetes (T2D). In total, 115 obese adults with T2D (sixty-six males, BMI: 34·6 (sd 4·3) kg/m2, age: 58 (sd 7) years, HbA1c: 7·3 (sd 1·1) %, diabetes duration: 8 (sd 6) years) were randomised to consume either an energy-restricted, very low-carbohydrate, low-saturated-fat (LC) diet or an energy-matched high unrefined carbohydrate, low-fat (HC) diet with supervised aerobic/resistance exercise (60 min, 3 d/week) for 52 weeks. Body weight, HbA1c and cognitive performance assessing perceptual speed, reasoning speed, reasoning ability, working memory, verbal fluency, processing speed, short-term memory, inhibition and memory scanning speed were assessed before and after intervention. No differences in the changes in cognitive test performance scores between the diet groups were observed for any of the cognitive function outcomes assessed (P≥0·24 time×diet). Percentage reduction in body weight correlated with improvements with perceptual speed performance. In obese adults with T2D, both LC and HC weight-loss diets combined with exercise training had similar effects on cognitive performance. This suggests that an LC diet integrated within a lifestyle modification programme can be used as a strategy for weight and diabetes management without the concern of negatively affecting cognitive function.

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.

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.

Cognitive performance in older adults is inversely associated with fish consumption but not erythrocyte membrane n-3 fatty acids.

Higher n-3 (ω-3) polyunsaturated fatty acids (PUFAs) and fish intake may help maintain cognitive function in older age. However, evidence is inconsistent; few studies have examined the relation in cognitively healthy individuals across numerous cognitive domains, and none to our knowledge have considered lifetime fish intake. We examined associations between multiple domains of cognition and erythrocyte membrane n-3 PUFA proportions and historical and contemporary fish intake in 390 normal older adults, analyzing baseline data from the Older People, Omega-3, and Cognitive Health trial. We measured n-3 PUFA in erythrocyte membranes, and we assessed historical and contemporary fish intake by food-frequency questionnaires. We assessed cognitive performance on reasoning, working memory, short-term memory, retrieval fluency, perceptual speed, simple/choice reaction time, speed of memory-scanning, reasoning speed, inhibition, and psychomotor speed. Cognitive outcomes for each construct were factor scores from confirmatory factor analysis. Multiple linear regression models controlled for a number of potential confounding factors, including age, education, sex, apolipoprotein E-ε 4 allele, physical activity, smoking, alcohol intake, socioeconomic variables, and other health-related variables. Higher erythrocyte membrane eicosapaentonoic acid proportions predicted slower perceptual and reasoning speed in females, which was attenuated once current fish intake was controlled. No other associations were present between n-3 PUFA proportions and cognitive performance. Higher current fish consumption predicted worse performance on several cognitive speed constructs. Greater fish consumption in childhood predicted slower perceptual speed and simple/choice reaction time. We found no evidence to support the hypothesis that higher proportions of long-chain n-3 fatty acids or fish intake benefits cognitive performance in normal older adults.

Retrospective lifetime dietary patterns are associated with demographic and cardiovascular health variables in an older community-dwelling Australian population.

Dietary patterns derived from factor analytic procedures have been demonstrated to predict demographic and health outcomes across a wide range of populations. To examine the potential utility of long-term dietary recall, in the present study, we examined associations between dietary patterns from across the lifespan and demographic and later-life cardiovascular-related health variables, using the Lifetime Diet Questionnaire (LDQ). The LDQ is a self-administered, non-quantitative, retrospective FFQ designed to assess dietary intake from childhood to older age. Participants (n 352) from the Older People, Omega-3 and Cognitive Health trial, aged 65-91 years, completed the LDQ. Exploratory factor analysis was conducted on the LDQ and plausible dietary patterns were derived. As a result, three patterns were extracted from each life period, with five distinct patterns overall; these were 'traditional Australian' and 'non-traditional Australian', 'high-sugar and high-fat', 'vegetable' and 'fruit and vegetable' patterns. In separate adjusted regression models, age, sex, education, income, parental background and childhood physical activity all significantly predicted dietary patterns across the lifespan. A 'traditional Australian' pattern in childhood predicted higher HDL-cholesterol levels and lower odds of cholesterol medication use; lower HDL-cholesterol levels were predicted by the adult 'processed, high-sugar and high-fat' pattern, and higher intake of a 'non-traditional Australian' pattern in adulthood also predicted lower odds of using cardiac medications. Lifetime dietary recall, as instantiated by the LDQ, provides a hitherto untapped source of long-term dietary information in older adults that may contribute to greater understanding of the impact exerted by early-life and cumulative dietary choices on later-life health.

The effect of beverages varying in glycaemic load on postprandial glucose responses, appetite and cognition in 10-12-year-old school children.

Reducing glycaemic index (GI) and glycaemic load (GL) inconsistently improves aspects of cognitive function and appetite in children. Whether altering the GL by lowering carbohydrate relative to protein and fat has a role in these effects is unknown. Therefore, we assessed the differential effects of beverages varying in GL and dairy composition on appetite, energy intake and cognitive function in children. A total of forty children (10­12 years) completed a double-blind, randomised, crossover trial, receiving three isoenergetic drinks (approximately 1100 kJ): a glucose beverage (GI 100, GL 65), a full milk beverage (GI 27, GL 5) and a half milk/glucose beverage (GI 84, GL 35). For 3 h post-consumption, subjective appetite and cognitive performance (speed of processing, memory, attention and perceptual speed) were measured hourly. At completion, each child was provided a buffet-style lunch and energy intake was calculated. Blood glucose was objectively measured using the Continuous Glucose Monitoring System. Blood glucose AUC values were significantly different between the drinks (P,0·001), but did not sustain above the baseline for 3 h for any drink. Mixed modelling revealed no effect of beverage on subjective appetite or energy intake. Participant sex and drink GL significantly interacted for short-term memory (P,0·001). When girls consumed either milk-containing beverage, they recalled 0·7­0·8 more words compared with 0·5 less words after the glucose drink (P#0·014). Altering GL of drinks by reducing carbohydrate and increasing protein did not affect appetite or cognition in children. Girls may demonstrate improved short-term memory after consuming beverages with higher protein and lower GL.

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.

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. TRIAL REGISTRATION: Australia and New Zealand Clinical Trials Register (ANZCTR): ACTRN12607000278437.

Assessing lifetime diet: reproducibility of a self-administered, non-quantitative FFQ.

OBJECTIVE: To demonstrate test-retest reliability (reproducibility) of a new self-administered lifetime diet questionnaire, with a focus on foods relevant to cognitive health in older age. DESIGN: The reproducibility of dietary recall over four or five life periods was assessed by administering the questionnaire at two time points to an older cohort. The period between questionnaire administrations was 7 weeks. Polychoric correlations measured the association between recall at time 1 and time 2 and the weighted κ statistic measured the level of recall agreement for food groups across the two administrations of the questionnaire. SETTING: Adelaide, South Australia. SUBJECTS: Fifty-two cognitively healthy, older-age, community-dwelling adults completed the Lifetime Diet Questionnaire; mean age 81·8 (SD 4·4) years, range 70-90 years. RESULTS: The questionnaire showed very good reproducibility in this sample with a mean polychoric correlation coefficient of 0·81 between administration at time 1 and time 2, and an average weighted κ of 0·49 for the level of recall agreement between food groups. CONCLUSIONS: The demonstrated reliability of this lifetime diet questionnaire makes it a useful tool to assess potential relationships between long-term dietary intake and later-age cognitive outcomes.

Individual differences in perceiving and recognizing faces-One element of social cognition.

Recognizing faces swiftly and accurately is of paramount importance to humans as a social species. Individual differences in the ability to perform these tasks may therefore reflect important aspects of social or emotional intelligence. Although functional models of face cognition based on group and single case studies postulate multiple component processes, little is known about the ability structure underlying individual differences in face cognition. In 2 large individual differences experiments (N = 151 and N = 209), a broad variety of face-cognition tasks were tested and the component abilities of face cognition-face perception, face memory, and the speed of face cognition-were identified and then replicated. Experiment 2 also showed that the 3 face-cognition abilities are clearly distinct from immediate and delayed memory, mental speed, general cognitive ability, and object cognition. These results converge with functional and neuroanatomical models of face cognition by demonstrating the difference between face perception and face memory. The results also underline the importance of distinguishing between speed and accuracy of face cognition. Together our results provide a first step toward establishing face-processing abilities as an independent ability reflecting elements of social intelligence.

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.

Toward a comprehensive test battery for face cognition: assessment of the tasks.

Despite the importance of face recognition in everyday life and frequent complaints about its failure, there is no comprehensive test battery for this ability. As a first step in constructing such a battery, we present 18 tasks aimed at measuring face perception, face learning, face recognition, and the recognition of facially expressed emotions. A sample of 153 healthy young adults completed all tasks. In general, reaction time measures showed high estimates of internal consistency; tasks focused on performance accuracy yielded reliabilities that were somewhat lower, yet high enough to support their use in a battery of face cognition measures. Some of the tasks allowed computation of established experimental effects in a within-subjects design, such as the part-whole effect. Most of these experimental effects were confirmed in our large sample, and valuable effect size estimates were obtained. However, in many cases these difference measures showed poor estimates of internal consistency.

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.

The role of individual differences in the accuracy of confidence judgments.

Generally, self-assessment of accuracy in the cognitive domain produces overconfidence, whereas self-assessment of visual perceptual judgments results in underconfidence. Despite contrary empirical evidence, in models attempting to explain those phenomena, individual differences have often been disregarded. The authors report on 2 studies in which that shortcoming was addressed. In Experiment 1, participants (N= 520) completed a large number of cognitive-ability tests. Results indicated that individual differences provide a meaningful source of overconfidence and that a metacognitive trait might mediate that effect. In further analysis, there was only a relatively small correlation between test accuracy and confidence bias. In Experiment 2 (N = 107 participants), both perceptual and cognitive ability tests were included, along with measures of personality. Results again indicated the presence of a confidence factor that transcended the nature of the testing vehicle. Furthermore, a small relationship was found between that factor and some self-reported personality measures. Thus, personality traits and cognitive ability appeared to play only a small role in determining the accuracy of self-assessment. Collectively, the present results suggest that there are multiple causes of miscalibration, which current models of over- and underconfidence fail to encompass.