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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.The aim of this study was to test whether docosahexaenoic acid (DHA)-rich fish oil slows 18-mo cognitive decline in cognitively healthy elders.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.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.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.

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.

Under this publisher’s copyright policy, authors are not permitted to make work available in an institutional repository., 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-ɛ 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., National Health and Medical Research Project Grant (no. 578800)

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.

The effect of Glycaemic Index (GI) and Load (GL) of breakfasts on satiety and aspects of cognitive function in children is inconclusive. We aimed to assess if isocaloric breakfasts differing in GL (by replacing high-GI carbohydrate foods with dairy protein foods) acutely alter cognitive function and satiety in 10- to 12-year-old children. A total of 39 children, aged 11.6±0.7 years with body mass index 18.9±3.0 kg/m2 (Mean±s.e.) participated in a randomised crossover trial of three isocaloric breakfasts (1.3 MJ): high GL (HGL: 7 g protein, 9 g fat, 50 g carbohydrate, GL 33); medium GL (MGL: 14 g protein, 9 g fat, 45 g carbohydrate, GL 24) and low GL (LGL: 18 g protein, 10 g fat, 38 g carbohydrate, GL 18). Blood glucose was recorded using a continuous glucose monitor. Subjective hunger and cognitive performance were measured before and hourly after consuming the test breakfast via a computer-delivered battery. Ad libitum intake at a buffet lunch meal was measured at 3 h at the end of testing. Incremental area under the glucose curve (iAUC) was significantly different with HGL>MGL>LGL (P

The purpose of this study was to replicate the structure of mental speed and relations evidenced with fluid intelligence (Gf) found in a number of recent studies. Specifically, a battery of computerized tasks examined whether results with paper-and-pencil assessments held across different test media. Participants ( N = 186) completed the battery, which incorporated 20 elementary cognitive tasks, 4 broad speediness (Gs) measures, and 5 Gf markers. Competing measurement models were tested. A higher-order model, with a general mental speed factor and 7 task-class specific factors fit the data well. Gs could not be distinguished from general mental speed. Besides the general mental speed factor, two task-class specific factors were moderately related to Gf. These findings strengthen the evidence for a multifacted structure of mental speed, and highlight the importance of specific speed task-classes in accounting for meaningful outcomes.

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.

The phase-synchronization of Gamma-band oscillations has been postulated as a mechanism of “network binding” and implicated in various aspects of perception, memory, and cognition. The current study investigates a possible link between Gamma synchrony and individual differences in intelligence within the theory of fluid and crystallized intelligence, with due reference to Hebbian theory. The hypothesis is that there are significant correlations between cognitive performance and synchronous Gamma activity across diverse brain regions. EEG data were recorded from 35 healthy participants, and the peak magnitude and latency of early and late Gamma Synchrony were extracted using a method for quantifying phase synchronization across multiple sites. Participants also completed 11 diverse cognitive ability tests tapping fluid and crystallized intelligence. Overall, moderate-sized correlations were obtained between accuracy and speed composite scores, derived from the ability tests, and magnitude and latency indices of Gamma synchrony. Phase-synchronous Gamma activity provides a plausible physiological mechanism that might account for individual differences in cognitive abilities.

Explored the factor structure of 14 elementary cognitive tasks as well as their relationships with processing speed (Gs) and fluid intelligence (Gf). A total of 321 US Air Force recruits (mean age 20 years) completed four tasks based on the Hick paradigm, four substitution tasks, three switching measures, and three odd-man-out measures assessing elementary cognitive abilities. In addition, three tasks measured Gs and six assessed Gf. Exploratory factor analyses suggested the presence of four task class factors with the possibility of a higher-order general mental-speed factor. Confirmatory factor analyses supported the higher-order model. This mental-speed factor correlated almost perfectly with the Gs factor, and also showed a high correlation with the Gf factor. A final measurement model containing both mental speed and Gf as well as the task class factors showed an acceptable fit. The results are considered evidence for a multidimensional conception of cognitive speed that includes a higher-order factor.

Generally, self-assessment of accuracy in the cognitive domain produces overconfidence, whereas self-assessment of visual perceptual judgments results in under- confidence. 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 dif- ferences 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. Col- lectively, the present results suggest that there are multiple causes of miscalibration, which current models of over- and underconfidence fail to encompass.

For any taxonomic model of cognitive abilities to be complete, lower-order sensory processes must be incorporated within its scope. The current study sought to address the role of olfactory processes within the theory of fluid and crystallized intelligence, as this sensory modality appears to have remained uninvestigated. Evidence from within experimental cognitive psychology suggests that olfactory memory is distinct from memory in other sensory modalities. Thus, this issue was also explored from an individual differences perspective. Participants (N=107) were tested on a battery of 12 psychometric tests, 4 putative cognitive olfactory tasks, and 1 olfactory discrimination measure. The resultant data set was subjected to exploratory factor analysis. Results indicate the likely existence of an olfactory memory ability that is structurally independent of established higher-order abilities and not related to simple olfactory sensitivity. The implication of this finding to models of human cognitive abilities is discussed.

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 (10–12 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 (PPP≤ 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.

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.

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.

1. Ian T. Zajac[1][1] 2. Nicholas R. Burns[1][1] 3. Vanessa Danthiir[2][2] 1. 1University of Adelaide, South Australia 2. 2CSIRO, Adelaide, South Australia 1. Ian Zajac, School of Psychology, University of Adelaide, South Australia 5005 Email: ian.zajac{at}adelaide.edu.au This study examined whether the broad ability general speediness (Gs) could be measured via the auditory modality. Existing and purpose-developed auditory tasks that maintained the cognitive requirements of established visually presented Gs markers were completed by 96 university undergraduates. Exploratory and confirmatory factor analyses showed that the auditory tasks combined with established visual measures to define latent Gs and reaction time factors. These findings provide preliminary evidence that suggests that if auditory tasks are developed that maintain the same cognitive requirements as existing visual measures, then they are likely to index similar cognitive processes. [1]: #aff-1 [2]: #aff-2

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