Objectives – Cognitive ageing is an inevitable part of human life. Research from disciplines such as epidemiology, medicine and neuroscience implicate a wide range of determinants in the pathophysiological processes that lead to clinical symptoms of neurodegeneration. Markers of systemic inflammation are postulated to play an important role in mechanisms underlying a neuro-pathological cascade, either directly, through neuro-inflammatory processes, or through the mediating effect of diseases that are associated with cognitive deficits, such as cardiovascular disease and variation and disruption to cerebral blood flow. This may be particularly important in people with type 2 diabetes, where the increased prevalence of vascular events and glycaemic upset along with elevated levels of various circulating biomarkers, have been implicated in accelerated cognitive decline. Increasingly, evidence suggests a contribution of vascular disease state in the development of Alzheimer’s disease in which inflammation could be a significant factor. Determining the direction of association between individual markers of inflammation and altered cognitive performance is important in order to understand the possible role of inflammation in the development of cognitive decline and to inform the development of preventive clinical interventions. Therefore investigating these risk factors in relation to the trajectory of age related cognitive decline is crucial; in this respect, longitudinal evidence, detecting change in cognitive performance over a defined period of time, is most appropriate. To date, the majority of evidence is inconclusive, predominantly due to methodological obstacles embedded in the prospective design of cognitive ageing studies and in the investigation of a complex disease state, such as insufficient follow up period and restricted cognitive assessment. Since associations reported from modelling late life cognitive change in epidemiological studies may be the result of confounding variables, such as gender, vascular risk factors/disease, education attainment and social status, investigating the causal nature of inflammatory mediators in cognitive decline, has proved more problematic. Additionally, even a casual association may be due to ‘reverse causation’. One method of unravelling such associations is through the use of genetic association, where the exposure variable of interest (such as genetic variants affecting plasma biomarker levels) is modelled against the outcome, thereby overcoming some of the problems of confounding and reverse causation inherent in non-genetic epidemiological studies. Aim – The primary aim of this thesis was to test for associations of baseline measures of acute-phase proteins (fibrinogen and C-reactive protein) and central pro-inflammatory cytokines (interleukin – 6 and tumour necrosis –α) with four-year change and estimated life-time change in cognitive ability in older people with type 2 diabetes. The second aim was to explore the association between fibrinogen-related SNPs (SNPs shown previously to be associated with altered plasma fibrinogen levels) and cognitive ability in the general population. Methods –Data from the Edinburgh Type 2 Diabetes Study (the ET2DS), a prospective epidemiological study of older people with type 2 diabetes were available, including that collected at a baseline clinic (2006-07) on 1066 participants, mean age 67.9 years (SD 4.2). For the present study, follow up cognitive assessment was carried out after four-years (2010-11) at which cognitive data was collected on 828 survivors. Cognitive ability at both time points was assessed using the same, comprehensive, seven neuropsychological tests battery, including measures of fluid as well as crystallised intelligence (vocabulary test). Principal component analysis was conducted to derive a general cognitive factor ‘g’ and a general inflammatory factor, derived from individual cognitive scores and from baseline measures of four inflammatory markers (fibrinogen and C-reactive protein, interleukin – 6 and tumour necrosis –α), respectively. Genotype and cognitive data were collected from seven, well-established population-based cohorts with clearly defined sampling frames and data collection procedures. Five cohorts comprised of community-dwelling elderly people, living in central Scotland (AAA Trial, n = 2061, EAS, n = 534; ET2DS, n = 1045; LBC 21, n = 517; LBC 36, n=1005) and two large were cohorts based in England (ELSA; n = 5458; and Whitehall II; n = 3400). In total, genotype and cognitive data were available for 14033 participants, age range between 60 to 80 years. In all studies cognition was assessed on three cognitive domains: memory, executive functioning and information processing. Compatibility of cognitive data allowed for calculation of a general cognitive factor ‘g’ that was comparable between all cohorts. The instrument variables consisted of 61 fibrinogen-related polymorphisms within 13 different loci. These were identified through a detailed literature search as well as through search of relevant, genetic databases. Results – in the ET2DS, the age and sex-adjusted analyses revealed statistically significant associations between raised plasma inflammatory markers and poorer ‘g’ at follow-up; this was observed for all biomarkers, with the strongest associations detected for IL-6 and the general inflammation factor (p values <0.001). These findings persisted in linear regression models of baseline biomarker levels with four-year cognitive change as well as estimated life-time change – here the general inflammatory factor and plasma IL-6 levels were the strongest predictors. Adjustment for conventional vascular risk factors and cardiovascular disease attenuated the associations of cognitive decline with fibrinogen, CRP and TNF-α; associations were largely attenuated in analyses assessing IL-6 and the general inflammation factor and tended to remain statistically significant. Meta-analysis was conducted in order to explore associations between pre-selected fibrinogen-related SNPs and impairment in general cognitive ability as indexed by ‘g’. The analysis identified five plasma fibrinogen-related SNPs that were significantly associated with impaired ‘g’ at the nominal threshold level of p < 0.05. These were: rs2070016 (FGB gene); rs2070016 (FGA gene); rs1800497 (ANKK1 gene); rs4251961 (IL1RN gene) and rs1130864 (CRP gene). Discussion – the results of the ET2DS indicate that in an elderly diabetic population, there is a significant relationship between baseline levels of circulating inflammatory markers and four-year cognitive change as well as estimated life-time cognitive decline. These associations were generally independent of common cardiovascular risk factors and events, suggesting a possible pathway where cytokine-induced activation of glial cells may be responsible for the consequent neuro-inflammatory processes resulting in declined cognitive ability. The lack of some associations may be due to a relatively short follow up period. The main strength of the ET2DS was the availability of prospective cognitive data, the large sample size and the use of a comprehensive cognitive battery, including a vocabulary test for crystallised intelligence and thus calculation of estimated life-time cognitive change. Genetic association analysis indicated a significant association between five preselected SNPs each located within different genes (in general, genes associated with inflammation), and impaired general cognitive ability. This provides some support for a causal role of inflammation in age-related general cognitive impairment. One of the major strength was the use of a large dataset and the applied methodological approach. Meta-analysis was conducted on raw, prospectively generated data, allowing determination of the cognitive phenotype variable. / The main outcomes of this thesis suggest that systemic inflammation may indeed be involved in aetiology of age-related cognitive decline, possibly via neuro-inflammation. Further epidemiological investigation should involve a measurement of biomarkers trajectories in modelling cognitive change. Use of a stronger genetic instrument for inflammatory biomarkers, modeled against cognitive decline rather than cognitive ability as in the current study could further advance knowledge of the bio-pathological mechanisms underlying age-related cognitive decline. Results could ultimately inform subsequent investigations in the form of a randomised control trial, testing an evidence-based anti-inflammatory clinical intervention in diabetic populations as well as the general populations.

Text in Afrikaans / 'n Ondersoek word gedoen na die aard, die oorsprong en die geloofwaardigheid van die inligtingsvetwerkingsbenadering in die kognitiewe sielkunde. Reeds vir die antieke Griekse denkers vorm logika 'n uitdrukking van die essensie van rede. Hierdie beskouing sou tydens die sewentiende eeu ontwikkel word tot die gedagte aan die subjek as 'n innerlike ruimte waarbinne die wereld van objekte in terme van logies-wiskundige rekonstruksies geken word. Die materialistiese beskouing reken dat alle dinge op hierdie wyse kenbaar is, maar ontken die subjek as vootwaarde vir sulke kennis, deur te poog om ook dit tot die objektiewe orde te reduseer. Die inligtingsteorie volg uit die ontstaan van die wiskundige logika, en hied 'n algemene teorie van probleemoplossing, die teorie van formele sisteme. Dit lewer 'n model vir die denke as die manipulering van simbole d.m.v. formele manipulasiereels. Hierdie simbole is abstrakte objekte, slegs onderskeibaar aan die hand van hulle vorm, maar kan onderling in hulle logiese samehang die wetmatige relasies tussen dinge soos dit in die wereld voorkom behou, en so dien as voorstellings van die wereld. Die funksionalistiese benadering tot denke is 'n poging om die probleem van die verhouding tussen denke en gedrag (die subjek-objekprobleem) op te los deur 'n toepassing van die inligtingsteorie. Funksionaliste wat die betekenisaspek of intensionele inhoud van die denke emstig opneem, reken dat terwyl voorstellings innerlik funksioneer as simbole in 'n formele sisteem, dit ook dien as verwysings na objekte in die ervaringswereld. Diegene wat 'n materialistiese reduksionisme aanvaarbaar vind ontken bloot die verwysingsvlak, en beskou die innerlike vetwerkings suiwer as sintaktiese prosesse. Aan die hand van 'n ontleding van die inligtingsvetwerkingsbenadering in verskillende manifestasies daarvan, word aangetoon dat die oplossing wat gebied word vir die probleem van die verhouding tussen denke en gedrag onsuksesvol is. Solank die onderliggende objektivistiese vooraannames gehandhaaf word, is die probleem waarskynlik in beginsel onoplosbaar. 'n Verskuiwing van perspektief is wenslik. Aandag moet gegee word aan die konkrete betrokkenheid van 'n mens in sy wereld, wat hy in handeling tot uitdrukking bring, en wat in taal binne 'n gemeenskaplike raamwerk geplaas word. / An inquiry is conducted into the nature, origins, and tenability of the information processing approach in cognitive psychology. Logic regarded as the essence of reason originates with classical Greek philosophy. In the seventeenth century this developed into the idea of the subject as an inner space where the world of objects is known by way of a mathematical-logical reconstruction. To materialists all things are known in this way, but the existence of the subject as a precondition for such knowledge is denied, by attempting to reduce it to the world of objects. Information theory developed in the wake of mathematical logic, and presents a general theory of problem-solving in the theory of formal systems. This suggests a model of the mind in terms of the manipulation of symbols by way of formal rules. Such symbols are abstract objects, individuated only by their form. Through the logical relationships among them they are able to maintain the lawlike relationships that exist among things in the world. In this way they serve as representations of the world. The functionalist approach to mind is an attempt to solve the problem of the relationship between thought and behaviour (i.e. the subject-object problem) by the application of information theory. Those functionalists that take the aspect of meaning or the intentional content of the mind seriously, argue that while representations function inwardly as symbols in a formal system, they also refer to objects in the world of experience. Materialist reductionists simply deny the level of referral, and view the inner computations as a purely syntactical process. By analyzing the information processing approach in various guises, it is shown that the solution given to the problem of the relationship between mind and behaviour does not succeed. As long as the underlying objectivist assumptions are maintained, this problem appears to be insoluble. A shift of perspective is suggested. Attention should be directed to the concrete involvement of a person with his world, as expressed in action, and how this is placed in a communal frame of reference through the power of language. / Psychology / D. Litt. et Phil. (Psychology)

Intentions have a special status in such important cognitive operations as prospective memory, or remembering to execute actions in the future. Indeed, recent research has shown that future-oriented information (such as intentions) have a higher and more sustained level of activation in mind than do other forms of to-be-remembered information. Such enhanced activation increases the accessibility of intentions for future retrieval operations, a phenomenon known as the “intention superiority effect.” Thus far, all research on the intention superiority effect has used facilitation paradigms, in which attending selectively to relevant stimuli facilitates performance on tasks that benefit from the processing of that information. The current investigation examines whether the intention superiority effect is also observed in an interference paradigm, in which sources of influence are in opposition. No previous research has demonstrated that the intention superiority effect is robust across such paradigm characteristics. Therefore, the first objective of the present study is to use a Stroop task to test the intention superiority effect within an interference paradigm. Previous research on the intention superiority effect has been conducted largely with undergraduate university students. Little is known about whether this effect exists for cognitively vulnerable populations, such as older adults. Arguably, the absence of an intention superiority effect could account for lower performance in such related cognitive tasks as prospective memory. Therefore, the second objective of this research was to examine whether the intention superiority effect, as produced by an interference paradigm, exists also for older adults. In a series of four experiments, participants received a brief Stroop word list including critical words from a previously encoded intention. We predicted that there would be more interference with colour naming for words that belonged to an intention that participants intended to carry out versus an intention that they did not have to carry out (i.e., intention superiority effect). Results of the four experiments for both young and older adults revealed longer latencies for words belonging to an intention that they intended to carry out. These data are the first demonstration of an intention superiority effect in an interference paradigm as well as the first demonstration of this effect in an older adult age group. / Graduate

No description available.

abstract: It is widely documented and accepted that athletes have difficulty maintaining adequate hydration status and that dehydration is a key risk factor for the heat-related illnesses commonly observed among athletes. Research has also suggested that hydration status can influence cognitive performance. Educational interventions focused on rehydration strategies have had minimal success reducing dehydration rates; hence, alternative interventions promoting adequate hydration status in athletes should be explored. This trial examined the efficacy of a commercial hydration mobile application (app) for reducing dehydration rates in campus athletes. Fifty-eight college students aged 18-40 y, who participated in club-level collegiate athletics were recruited from a large Southwestern university and randomized by team to one of two study arms, the Standard of Care – Education (EDU) or the hydration mobile app (APP), to determine if app technology improved hydration status as compared to traditional education messaging. Twenty-three (79%) in the EDU group and twenty (69%) in the APP group were mildly-dehydrated at baseline based on the three-day averages of hydration assessment (USG 1.010). Moreover, 31% (n=9) and 28% (n=8) of the EDU and APP groups, respectively, were dehydrated (USG 1.020). No significant differences were found between the EDU and APP groups following the intervention. Three-day average post-intervention USG testing showed 76% (n=22) and 72% (n=21) of the EDU and APP groups respectively were at best mildly-dehydrated. Additionally, 28% (n=8) and 17% (n=5) were considered dehydrated. Neither intervention improved hydration status after four weeks of treatment. Further analyses of cognitive measures were conducted by hydration assessment groups at baseline and post-intervention: hydrated (HYD) (USG < 1.020) or dehydrated (DEH) (USG 1.020). No significant differences between hydration status were found between intervention groups. Additionally, no significant improvements were seen for either group, which indicates there is still a need for a novel way to improve hydration status in this population. Multi-dimensional interventions and individualized interventions to improve hydration status in this at-risk population may be more effective. Additional research should be conducted to determine if there is any cognitive performance enhancement associated with dehydration or mild-dehydration by reassessing previous data and conducting future trials. / Dissertation/Thesis / Doctoral Dissertation Physical Activity, Nutrition and Wellness 2017

The series of experiments reported in this thesis concern the ability to make perceptual-motor judgements of distance (Ex. 1 to Ex. 7) and size (Ex. 8). Experiments 1 and 2 indicated that visual judgements of maximum step length were effected by; distance from the site of action, the angle at which the obstacle was presented and whether monocular or binocular vision was used. This suggested that perceived maximum ability was not based on a body scaled invariant as suggested by Gibson (1979). Experiments 3 and 4 were designed to investigate the effect of altering the length of distance to-be-remembered, and compared performance across both visual and kinaesthetic conditions. The results suggested that the reproduction of distance is normally based on memory for the location of the end point, rather than the extent of the distance. No support was found for the claim that differences between the accuracy of recall of location and extent was due to the differential rehearsability of visual and kinaesthetic codes. Instead, it was proposed that changes in the procedure may have influenced performance by reducing the usefulness of a 'landmark' based form of coding in the extent trials. Experiments 5 and 6 were designed to investigate predictions arising from one of the dominant models of cross-modal performance (Connolly and Jones, 1970). Connolly and Jones's model postulated that differences between intra- and cross-modal performance could be explained in terms of the characteristics of modality specific short-term storage codes, and that translation between codes occurs prior to short-term storage. In general the results obtained were supportive of the pattern of accuracy reported by Connolly and Jones. However, the effect of delaying until the end of the retention interval knowledge of the reproduction mode was inconsistent with the model, that is, withholding information about the required reproduction mode appeared to increase the accuracy of judgements. One explanation for this effect is that pre-translated information was held in a form which was associated with high levels of both accuracy and attention. This speculative explanation was seen to have parallels with the Working Memory model (Baddeley and Hitch, 1974). Experiments 7 and 8 used an interference task paradigm to investigate whether a separate visuo-spatial store could be demonstrated to exist in relation to perceptual-motor information. The results failed to find conclusive support for such a store. The cumulative findings of Experiments 1 to 8 are discussed in relation general models of perceptual-motor performance.

M.A. (Psychology) / Please refer to full text to view abstract

Whereas previous research has demonstrated that trait ratings of faces at encoding leads to enhanced recognition accuracy as compared to feature ratings, this set of experiments examines whether ratings given after encoding and just prior to recognition influence face recognition accuracy. In Experiment 1 subjects who made feature ratings just prior to recognition were significantly less accurate than subjects who made no ratings or trait ratings. In Experiment 2 ratings were manipulated at both encoding and retrieval. The retrieval effect was smaller and nonsignificant, but a combined probability analysis showed that it was significant when results from both experiments are considered jointly. In a third experiment exposure duration at retrieval, a potentially confounding factor in Experiments 1 and 2, had a nonsignificant effect on recognition accuracy, suggesting that it probably does not explain the results from Experiments 1 and 2. These experiments demonstrate that face recognition accuracy can be influenced by processing instructions at retrieval.

This study was designed to explore specific aspects of the relationship between language and cognition. Comparisons of a normal population with populations deficient in verbal ability provide information relevant to the qualification of this relationship. In this respect, B.C. Indian children were an appropriate group for comparison with normal white children since they are apparently deficient in verbal development. It was considered worthwhile to determine if there are cognitive differences between Indian and white children and if there are, to determine if these differences can be attributed to differences in verbal ability in the form of verbal mediation. Evidence of verbal mediation is assumed to be exemplified in the relatively greater ease of executing a R over a NR shift. In a 3 x 2 x 2 factorial design involving age (7,8,9), shift (R-NR), and ethnic group (Indian-white), it was hypothesized that there would be a significant interaction between shift and ethnic group. A total of sixty-seven Indian and fifty-one white children was initially tested. However, nineteen Indian and three white children failed to learn the first discrimination to criterion within the limit of one hundred trials. The difference between these proportions was highly significant. Analyses were conducted for the resulting self-selected sample of forty-eight Indian and forty-eight white children who succeeded in attaining the first criterion and who went on to the shift task. On original learning, there were no significant differences or interactions for this self-selected sample. On the shift, there was a significant main effect only for the shift factor, with the R shift performance being superior to MR shift performance for both ethnic groups. There were no differences between Indians and whites in overall performance or in the relative difficulty of R and NR shifts. Supplementary analyses were performed to explore other possible differences. It was found that the white children were relatively consistent in the speed with which they learned both the original discrimination and shift while, in contrast, the Indian children were not. Those Indian children who were "fast" in original learning became "slow" on the shift, whereas those who were"slow" in original learning became "fast" on the shift. On the basis of post-experimental card sort and verbalization tests, it was also found that the shape dimension was more salient than the size dimension and that Indian children were not as successful in giving an appropriate overt label to the triangle concept. The specific hypothesis that there would be a significant interaction between shift and ethnic group was not supported. However, in general, the results from the supplementary analyses and the fact that significantly more Indian than white children failed to reach the first criterion suggested that there wore cognitive differences between Indian and white children. There was no specific evidence to support a mediational deficiency interpretation of these differences. / Arts, Faculty of / Psychology, Department of / Graduate

Quelle est la vraie nature de l’âgisme, comment l’explique-t-on et comment le mesure-t-on ? Voici les trois principales interrogations qui ont guidé notre travail. Nous avons essayé d’étudier ce phénomène sous l’angle des théories et des paradigmes les plus récents de la cognition sociale qu’elle soit explicite ou implicite. Cette thèse se compose de deux parties : une partie théorique et une autre empirique. Dans la première, nous avons tenté d’explorer la nature de l’âgisme : est-il une attitude, un stéréotype ? Comment fonctionne-t-il ? Comment agit-il? Comment l’explique-t-on ? Plusieurs théories explicatives ont été explorées telles que la perspective sociocognitive des stéréotypes de l’âge, la théorie de l’identité sociale, la théorie de la double norme du vieillissement ou encore la théorie de gestion de la terreur. Sans oublier le rôle de certains aspects de la personnalité dans les différences individuelles liées à l’âgisme. Un autre aspect majeur abordé est celui de l’âgisme implicite présenté sous l’angle de la cognition sociale implicite. La seconde partie présente six études empiriques. Les deux premières portent sur l’âgisme explicite et se proposent d’adapter et valider une mesure directe de l’âgisme, ainsi que de soumettre à l’épreuve des faits un modèle structural mettant en jeu certaines variables de personnalité explicatives des préjugés. A notre connaissance, nous offrons à travers ce travail, la première mesure directe francophone de l’âgisme, dûment validée. Les quatre autres études expérimentales portent sur l’âgisme implicite. Les deux premières concernent la construction et la validation d’une mesure indirecte de l’âgisme. Nous avons retenu le Single Category Implicit Association Test (SC-IAT) pour construire une mesure indirecte absolue par opposition à une mesure relative produite par le célèbre Implicit Association Test (IAT). Nous offrons aussi à travers ce travail, la première mesure indirecte absolue de l’âgisme en opposition aux mesures indirectes relatives utilisant l’IAT. La troisième explore l’âgisme implicite à la lumière du paradigme des stéréotypes multiples de l’âge et de la théorie de la gestion de la terreur. Enfin, la dernière explore l’âgisme implicite à la lumière de la double norme du vieillissement. / What is the real nature of ageism? How do we explain and measure it? Here are the three main questions which have guided our work. We have tried to study this phenomenon from the theories and most recent paradigms perspectives of the social cognition whether they are explicit or implicit. The thesis is divided in two parts: One is theoretical while the other one is empirical. In the first one, we have tried to explore the nature of ageism: Is it an attitude, a stereotype? How does it function? How does it act? How do we explain it? Several explicative theories have been explored such as the social cognitive perspective of age stereotypes, the social identity theory, the double standard of aging and the terror management theory without omitting the role of certain aspects of personality in the individual differences linked to ageism. Another important factor is the implicit ageism as seen in the implicit social cognition. The second part deals with 6 empirical studies. The first two parts are about explicit ageism and try to adapt and validate a direct measure on ageism. This measure is therefore integrated to a structural model which includes certain personality variables related to generalized prejudice. To our knowledge, we introduce through this study the first French direct measure on ageism duly validated. The other four experimental studies deal with implicit ageism when the first two studies concerned the construction and validation of an indirect measure of ageism. We have used the Single Category Implicit Association Test (SC-IAT) to build an absolute indirect measure as opposed to a relative measure produced by the famous Implicit Association Test (IAT). The third study explores the implicit ageism through the paradigm of multiple stereotypes due to age and terror management theory. Finally, the last one explores implicit ageism through the double standard of aging.