| 1. |
- Hedner, Margareta, 1981-
(author)
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Olfactory Function : The Influence of Demographic, Cognitive, and Genetic Factors
- 2013
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Doctoral thesis (other academic/artistic)abstract
- Olfactory function is affected by demographic, cognitive, and genetic factors. In the present thesis, three empirical studies investigated individual differences in olfactory ability. Study I explored demographic and cognitive correlates in common olfactory tasks; odor detection, odor discrimination, and odor identification. The results indicated that old age influenced performance negatively in all tasks, and that semantic memory proficiency and executive functioning were related to odor discrimination and odor identification performance. No cognitive influence was observed for measurements of olfactory threshold. Using population-based data, Study II investigated a potential influence of the ApoE gene on olfactory identification after controlling for health status, semantic memory, and preclinical and clinical dementia. The main finding was that the ApoE- ɛ4 allele interacted with age, such that older ɛ4-carriers had an impaired odor identification performance relative to older non-carriers. Importantly, the negative ApoE- ɛ4 effect on olfactory proficiency was independent of clinical dementia conversion within five years. Study III investigated the effects of the BDNF val66met polymorphism on olfactory change over a five-year interval, in a community dwelling sample of young and old age cohorts. The results showed that age-related decline in olfactory identification was influenced by the BDNF val66met. In middle-aged subjects, no effect of BDNF val66met was observed although older val homozygote carriers showed a selectively larger olfactory decline than the older met carriers. Overall, results suggest that the relative influence of demographic and cognitive factors vary across different olfactory tasks and that two genes (ApoE and BDNF) impact age-related deficits in odor identification. Potential theoretical and practical implications of the findings are discussed as well as potential limitations of association studies in genomics research.
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| 2. |
- Eriksson Sörman, Daniel, 1974-
(author)
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The influence of social relationships and leisure activity on adult cognitive functioning and risk of dementia : Longitudinal population-based studies
- 2015
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Doctoral thesis (other academic/artistic)abstract
- Today, as we live longer, dementia diseases are becoming more prevalent around the world. Thus, further knowledge of how to maintain levels of cognitive functioning in old age and how to identify factors that postpone the onset of dementia are of acute interest. Lifestyle patterns and social life are important aspects to consider in this regard.This thesis includes three studies. Study I investigated the association between participation in various leisure activities in old age (≥65 years) and risk of incident all-cause dementia. Analyses of the total follow-up time period (15 years) showed that higher levels of “Social” and “Total” leisure activity were associated with decreased risk of dementia. In Study II, the aim was to investigate the association between various aspects of social relationships in old age (≥65 years) and risk of incidents of all-cause dementia and Alzheimer's disease. Results showed that over the total follow-up period (16 years) higher values on the relationship index were associated with reduced risk of both dementia and Alzheimer's disease. Visiting/visits of friends and acquaintances more than once a week was related to decreased risk for all-cause dementia, but not for Alzheimer's disease. However, in neither Study I nor II did any of these factors alter the risk of all-cause dementia or Alzheimer's disease when near-onset dementias were removed from the analyses (Study I, up to five years; Study II, up to three years).In Study III the aim was to investigate the association between social network size and cognitive ability in a middle-aged (40–60 years) sample. The idea was that if social network size can moderate negative age-related influence on memory functions, it might also put an individual on a cognitive trajectory that is beneficial in old age. Results from longitudinal analyses showed that baseline network size was positively related to five-year changes in semantic memory and with changes in both semantic and episodic memory at the ten-year follow-up. Social network size was unrelated to changes in visuospatial performance.Taken together, enrichment factors measured in old age (≥ 65 years) did not alter the risk of all-cause dementia or Alzheimer's disease when near-onset dementias were removed from the analyses. These results might reflect protective short-term effects or reverse causality, meaning that in the prodromal phase of dementia individuals tend to withdraw from activity. Social network size in middle age (40-60 years), however, appears to have beneficial long-term effects on cognitive functioning. The results highlight the importance of long follow-up periods and the need to adjust for the influences of reverse causality when investigating the impact of a socially and mentally active life on cognitive functioning.
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| 3. |
- Essen, Jan von, 1973-
(author)
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Helping Hands : Motion and integration in action memory
- 2005
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Doctoral thesis (other academic/artistic)abstract
- Verbal information has predominantly been the to-be-remembered materials in human memory research for more than a century. In recent years some interesting deviations from the established rules of verbal memory have been observed in subjects who have been asked to motorically self-perform (enact) action sentences at the encoding phase of the memory task, instead of only hearing or reading them as in a traditional verbal task (VT). Marked enhancements in recall were also consistently demonstrated in such studies and the effect was named the subject-performed task (SPT) effect. Presently, the body of SPT research is large but little agreement has been reached regarding the mechanism at work in producing the SPT phenomenon. The present thesis addresses two major issues in SPT research. The enhancement of associative information and the significance of the motor component are evaluated. In Study A, the SPT effect was studied in two cued-recall tasks that relied on item-specific association and relational association, respectively. The results showed that SPT encoding interacts with item-specific associative cues at recall to produce a larger SPT effect as compared to free recall. This supports the notion that part of the SPT effect is due to enhanced item-specific association. In Study B, the associative effect in SPT was studied amongst age cohorts comprised of subjects between 40 and 85 years old. Normal age-related decline in episodic memory has elsewhere been suggested to be caused mainly by associative deficits connected with ageing. The results of Study B indicate that the item-specific associative effect in SPT was more age sensitive than recall of VT and the relational associative effect in SPT. In Study C, the question over whether the SPT effect is dependent on motor modality or not was addressed. Self-produced sign language encoding was argued to be qualitatively the same as self-produced oral/verbal encoding, with the motor modality component being the only exception. It was also argued that the motor modality component was the main similarity to performing SPT. Since the signing subjects performed at the same level as the SPT condition at recall, and better than the control conditions (e.g., VT), the conclusion was made that motor activation per se can contribute to memory enhancement in SPT. Whether SPT encoding results in qualitatively different memory traces is discussed as well as the effect of SPT on other types of associative information. The results are also briefly related to other controversies in SPT research. It is concluded, finally, that enactment produces differential effects on different types of associations. The association between verb and noun is clearly enhanced by SPT encoding. Moreover, it is concluded that overt motor activation is necessary for obtaining a full SPT effect. To explore these interactions further and to build upon these conclusions, an increased focus on motor processes and their relation to verbal processes is called for in future cognitive research.
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| 4. |
- Holmgren, Sara, 1974-
(author)
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Effects of family configuration on cognitive functions and health across the adult life span
- 2007
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Doctoral thesis (other academic/artistic)abstract
- This thesis examines whether childhood family configuration influences performance on cognitive functions and health in adulthood and old age. All studies examined participants in the Betula Prospective Cohort Study aged 35 to 85 years (Nilsson et al., 1997). Study Ι established whether there are reliable effects of sibship size and birth order in a large sample of participants in adulthood and old age. The results showed that the effects previously demonstrated in children and adolescents (e.g., Belmont & Marolla, 1973; Mercy & Steelman, 1982) have a long-lasting effect and can be demonstrated in an adult sample. These studies concluded that intelligence and executive functioning decreased as the sibship size increased. Birth order, in contrast, had only influenced executive functions and working memory: earlier born siblings performed at a higher level than later born siblings. Study ΙΙ examined whether the effects of sibship size and birth order can be replicated and extended to episodic memory and whether the effects of family configuration are stable over a five-year interval. The results showed that early born siblings and siblings belonging to a smaller sibship size performed at a higher level and that these effects on both recall and recognition were stable over a five-year interval. Study ΙΙΙ explored whether childhood family configuration influences chronic adult diseases (myocardial infarction and circulatory disorders, stroke, and hypertension). The overall results showed that being born in a large sibship is a risk factor for stroke, myocardial infarction /circulatory disorders, and hypertension in old age. The results also suggest that being born early in a sibship is a predictor of stroke.
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| 5. |
- Karlsson, Thomas, 1953-
(author)
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Cognitive and neuropsychological aspects of age-associated memory dysfunction
- 1991
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Doctoral thesis (other academic/artistic)abstract
- Memory dysfunction is common in association with the course of normal aging. Memory dysfunction is also obligatory in age-associated neurological disorders, such as Alzheimer’s disease. However, despite the ubiquitousness of age-related memory decline, several basic questions regarding this entity remain unanswered. The present investigation addressed two such questions: (1) Can individuals suffering from memory dysfunction due to aging and amnesia due to Alzheimer’s disease improve memory performance if contextual support is provided at the time of acquisition of to-be- remembered material or reproduction of to-be-remembered material? (2) Are memory deficits observed in ‘younger’ older adults similar to the deficits observed in ‘older’ elderly subjects, Alzheimer’s disease, and memory dysfunction in younger subjects?The outcome of this investigation suggests an affirmative answer to the first question. Given appropriate support at encoding and retrieval, even densely amnesic patients can improve their memory performance. As to the second question, a more complex pattern emerges. When attentional demands are varied, subjects of varying ages perform qualitatively similar. However, when semantic aspects of the to-be- remembered material are manipulated, age-associated qualitative differences are observed. These qualitative differences show up between older and younger adults, as well as between ‘younger’ and ‘older’ elderly subjects.
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| 6. |
- Kubik, Veit, 1981-
(author)
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Effects of Testing and Enactment on Memory
- 2014
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Doctoral thesis (other academic/artistic)abstract
- Learning occurs not only when we encode information but also when we test our memory for this information at a later time. In three empirical studies, I investigated the individual and combined effects of interleaved testing (via repeated rounds of study and test practice) and encoding (via motor enactment) during learning on later cued-recall performance for action phrases. Such materials (e.g., “water the flowers”) contain a verb and a noun and approximate everyday memory that typically revolves around past and future actions. Study I demonstrated that both interleaved testing (vs. study only) and enactment (vs. verbal encoding) individually reduced the forgetting rate over a period of 1 week, but these effects were nonadditive. That is, the direct testing effect on the forgetting rate occurred for verbal, but not for enactive encoding; enactment reduced the forgetting rate for the study-only condition, but not for the study–test condition. A possible explanation of these findings is that both study techniques sufficiently elicit verb–noun relational processing that cannot be increased further by combining them. In Studies II and III, I replicated these testing-effect results and investigated whether they varied as a function of recall type (i.e., noun-cued recall of verbs and verb-cued recall of nouns). For verbal encoding (Study II), the direct testing effect was of similar size for both noun- and verb-cued recall. For enactive encoding, the direct testing effect was lacking irrespective of recall type. In addition, interleaved tests enhanced subsequent re-encoding of action phrases, leading to an accelerated learning. This indirect testing effect was increased for the noun-cued recall of verbs—for both verbal and enactive encoding. A possible explanation is that because nouns are semantically more stable, in that the meaning of nouns changes less over time and across different contexts, they are more recognizable. Hence, associated information (e.g., about the recall status) may be more available to the learner during restudy that, in turn, can initiate more effective re-encoding. The two different testing benefits (i.e., direct and indirect) may, partly, engage different mechanisms, as they were influenced differentially by the manipulations of encoding type and recall type. The findings presented in the thesis provide new knowledge regarding the combined effects of strategies and materials that influence memory.
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| 7. |
- Lewin, Catharina, 1972-
(author)
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Sex Differences in Memory and Other Cognitive Abilities
- 2003
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Doctoral thesis (other academic/artistic)abstract
- The aim of the present thesis was to study sex differences in memory and other cognitive bilities in healthy adults. In Study I, participants performed a number of episodic memory tasks that were more or less verbal in nature. Results showed that women performed on a higher level than did men in the episodic memory tasks where it was possible to use verbal labels, whereas men performed on a higher level than did women in a visuospatial episodic memory task. In Study II, women’s advantage in face recognition was investigated.Results showed that women performed at a higher level than did men only in the recognition of other women’s faces. In Study III, sex differences in cognitive tasks as well as brain measures were investigated in healthy older adults. Results showed that only the sex differences in a motor task could, to some extent, be explained by sex differences in one of the brain measures. The findings, as well as possible explanations for these patterns of results, are discussed in a theoretical context.
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| 8. |
- Moniri, Sadegheh, 1959-
(author)
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Bilingual memory : A lifespan approach
- 2006
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Doctoral thesis (other academic/artistic)abstract
- Bilingualism and its effect on individuals have been studied within different disciplines. Although the first psychological study of bilingualism was couducted by Cattell as early as 1887, only a few studies have exclusively investigated the effect of bilingualism on memory systems’ functioning. In the field of cognitive psychology of bilingualism, there is some evidence for the positive influence of bilingualism on children’s cognitive ability across various domains but there is little knowledge about the relationship between bilingualism and memory in a lifespan perspective. This thesis’s main aim was to investigate memory systems’ functioning and development in bilingual individuals. To this end, two studies were performed: a cross-sectional study of bilingual children (Study I) and a longitudinal study of young and older adults (Study II). The purpose of Studies I and II was to determine whether there are differences between monolinguals and bilinguals regarding various memory systems’ functioning. Study I compared monolingual and bilingual children’s performance on episodic and semantic memory, and Study II investigated performance on episodic and semantic memory in bilingual younger and older adults. Specifically, these studies aimed to examine a) which memory systems will be affected more as a function of language, and b) to what extent the differences would manifest themselves during a subject’s lifespan. The purpose of Study III was to explain the relation among word representations, lexical access and lexical selection in a bilingual word production paradigm. In this study, a model of bilingual production was developed to explain the results and clarify the role of automatic and controlled processes in using two languages. The results of Studies I and II showed a superiority of bilinguals over monolinguals as well as a variation of association between memory performance and bilingualism across different periods of adulthood. It appears that the lifelong experience of managing two languages enhances control processes, which in turn play an important role in enhancing memory performance. Using a “dual mechanism model”, Study III explains the efficiency of inhibitory processing when having two languages activated.
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| 9. |
- Mousavi-Nasab, S. M. Hossein, 1979-
(author)
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Engaged lifestyle and episodic and semantic memory : longitudinal studies from the betula project
- 2012
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Doctoral thesis (other academic/artistic)abstract
- This dissertation examines whether some aspects of engaged lifestyle, marital status and leisure activity, influence memory performance in adulthood and old age. Direct effects and indirect effects, via health, are investigated. All the studies in the dissertation examine participants in the Betula project, aged 35 to 85 years. Study I investigates whether there are reliable effects of marital status on memory function in a large sample of participants in adulthood and old age. The results demonstrate that marriage has an influence on some specific types of memory functions. They show that there are significant differences between married and single individuals in episodic memory, but not in semantic memory. Also, the extent of decline in episodic memory was found to be significantly larger for singles and widowed individuals than for married people over five years. Study II examines the relationships between different types of social and cognitive activities and episodic and semantic memory. The results show that a unidirectional effect of social activity on episodic memory was detectable on all test occasions. Also, episodic memory predicted change in cognitive activity during all test waves. However, there were no significant effects with regard to semantic memory and leisure activity in either direction. Study III explores longitudinally whetherengaged lifestyle, including marriage and leisure activity, directly affects memory performance, or whether the effect is mediated by health. The overall results demonstrate that marriage predicts episodic memory function directly. Leisure activity can also predict episodic memory performance ten years later, but indirectly via health. An active and engaged lifestyle can protect people against memory decline. The positive impact of engaged lifestyle on memory performance is discussed in terms of cognitive reserve theory, and in relation to the decrease in distress afforded by social support from other people.
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| 10. |
- Mäntylä, Timo, 1954-
(author)
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How do you cue? : self-generated retrieval cues and successfull recall
- 1986
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Doctoral thesis (other academic/artistic)abstract
- The present thesis deals with the determinants of good memory performance. A more specific objective of the thesis was to examine prerequisites for successful recall performance from the point of view of cue effectiveness. The concept of cue effectiveness was proposed as a superordinate construct underlying the act of remembering in general as well as,exceptional memory performance. It was argued that to the extent that effective cues are provided when retrieval is attempted, good recall would be obtained even without use of specific mnemonic systems. Two characteristics of cue effectiveness were assumed to determine the level of recall performance. First, a retrieval cue has to provide a compatible description of the information encoded, and second, an optimal cue is the one that also represents a distinctive description of that information. Provided that these two characteristics of cue effectiveness are fullfilled, successful recall was expected to occur. In order to optimize cue efficiency an experimental paradigm was introduced. The main feature of the self-generation paradigm is that, in contrast to traditional cued-recall experiments, subjects are provided with cues, which according to the individual's own conceptualization constitute an appropriate description of the previously encoded information. The four studies composing the empirical section of the thesis, demonstrated, first, that self-generated cues serve as extremely powerful retrieval aids. Secondly, it was demonstrated that compatibility and distinctiveness may be the cardinal concepts underlying the empirical phenomenon per se and the essence of the notion of cue effectiveness. Finally, it was proposed that the methodological contribution is of such a nature that it may apply successifully to more practical situations.
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