Biomedical subjects

Lars-Göran Nilsson

Publications and source records attributed to Lars-Göran Nilsson.

13 recordsLinked to original sources

PubMed2003

Sex differences in recollective experience for olfactory and verbal information.

We examined recollective experience as a function of sex for olfactory and verbal information. In the first study, men and women studied a set of highly familiar odors with incidental or intentional encoding instructions. In the second study, participants were presented with a number of sentences. At recognition, participants indicated whether their positive response was based on conscious recollection (remembering), a feeling of familiarity (knowing), or guessing. The results indicated that recollection was higher among women than men, and that familiarity-based recognition was equally large across sex for both types of information.The finding that the sex-related experiential difference disappeared when controlling for verbal proficiency suggests that sex-related differences in activating verbal information play an important role for sex differences in recollective experience.

Adult↗

PubMed2003

Memory function in normal aging.

Basic findings obtained on memory functions in normal aging are presented and discussed with respect to five separate but interacting memory systems. These systems are: episodic memory, semantic memory, short-term memory, perceptual representation system and procedural memory. All available evidence from cross-sectional research shows that there is a linear, decreasing memory performance as a function of age for episodic memory. Longitudinal studies suggest, however, that this age deficit may be an overestimation, by showing a relatively stable performance level up to middle age, followed by a sharp decline. Studies on semantic memory, short-term memory, perceptual representation system, and procedural memory show a relatively constant performance level across the adult life span, although some tasks used to assess short-term memory and procedural memory have revealed an age deficit. Disregarding the mixed results for these latter two memory systems, it can be concluded that episodic memory is unique in showing an age deficit. Episodic memory is also unique in the sense that it is the only memory system showing gender differences in performance throughout the adult life span with a significantly higher performance for women.

Adult↗

PubMed2003

Selective adult age differences in an age-invariant multifactor model of declarative memory.

Confirmatory factor analysis was used to test competing models of declarative memory. Data from middle-aged participants provided support for a model comprised of 2 2nd-order (episodic and semantic memory) and 4 1st-order (recall, recognition, fluency, and knowledge) factors. Extending this model across young-old and old-old participants established support for age invariance. Tests of group differences showed an age deficit in episodic memory that was more pronounced for recall than for recognition. For semantic memory, there was an increase in knowledge from middle to young-old age and thereafter a decrease. Overall, the results support the view that episodic memory is more age sensitive than semantic memory, but they also indicate that aging has differential effects within these 2 forms of memory.

Adult↗

PubMed2003

Cigarette smoking and cognitive performance in healthy Swedish adults.

BACKGROUND: The relationship between cigarette smoking and cognitive function was examined in healthy Swedish adults who were participants in the Betula Prospective Cohort Study of Aging, Memory, and Health. SUBJECTS: The data are from those individuals in the Betula study who were self-reported continuous smokers contrasted to those who reported never smoking cigarettes. DESIGN: The dependent variables were cognitive tasks that varied with respect to difficulty and the demand they placed on processing resources. RESULTS: Current smokers performed more poorly than never smokers on the more cognitively demanding tasks; namely, Block Design and free recall. CONCLUSIONS: The findings were interpreted in the light of the assumption that cigarette smoking may exert its greatest deleterious effect on those cognitive tasks that place the heaviest demands on processing resources.

Adult↗

PubMed2003

Episodic and semantic memory in bilingual and monolingual children.

Although bilinguality has been reported to confer advantages upon children with respect to various cognitive abilities, much less is known about the relation between memory and bilinguality. In this study, 60 (30 girls and 30 boys) bilingual and 60 (30 girls and 30 boys) monolingual children in three age groups (mean ages 8.5, 10.5 and 12.5 years) were compared on episodic memory and semantic memory tasks. Episodic memory was assessed using subject-performed tasks (with real or imaginary objects) and verbal tasks, with retrieval by both free recall and cued recall. Semantic memory was assessed by word fluency tests. Positive effects of bilingualism were found on both episodic memory and semantic memory at all age levels. These findings suggest that bilingual children integrate and/or organize the information of two languages, and so bilingualism creates advantages in terms of cognitive abilities (including memory). Some sex differences were also found in episodic memory but not in semantic memory. This episodic memory difference was found with younger children.

Adolescent↗

PubMed2003

Primed word-fragment completion and successive memory test performance in normal aging.

Young and old subjects were investigated to examine whether: the effects of priming are influenced by aging; there is independence between primed word-fragment completion and recognition performances; and the dependence between different tests is influenced by aging. A successive test paradigm was employed involving repeated assessment of to-be-remembered words by means of recognition and primed word-fragment completion. The results show that implicit memory declines with increasing age, and that correlations between different memory tests decrease with age. The outcome suggests that age-related memory decline involves several forms of memory, including primed word-fragment completion, and is reflected in correlations between measures of implicit and explicit memory.

Aged↗

PubMed2003

Recognition memory in Alzheimer's disease. A demonstration of a remarkable memory capacity in Alzheimer's disease.

A compelling feature of human memory is its striking capacity. Under certain circumstances, subjects can remember large amounts of information even with brief exposure at study. This investigation shows that this ability is preserved even in severely impaired Alzheimer's disease patients, and this holds implications for the clinical management of amnesic patients. To this date, demonstrations of preserved learning and memory capacity in Alzheimer's disease and amnesia have been confined to implicit memory tasks. Since the present results were obtained in an explicit memory task, the finding also holds implications for the understanding of amnesia.

Alzheimer Disease↗

PubMed2003

Memory effects of motor activation in subject-performed tasks and sign language.

Research on memory has consistently shown that when a subject-performed task (SPT) is compared with a traditional verbal task (VT), enactment at the encoding of verbal materials (i.e., SPT) yields better memory performance than does nonenactment (i.e. VT). There is some controversy regarding the extent to which motor activation per se might be causing this effect, and whether or not SPTs may be influenced by memory strategies. The purpose of this study was to contribute toward a solution of these questions. The effect of SPT encoding was compared with the effect of encoding by means of a sign language task (SLT). The SLT condition is claimed to be a verbal/linguistic task with a major relevant motor component. The motor activation in SLT is in the present study seen to be the main difference between the SLT and the VT, and the main similarity between the SLT and the SPT. Control conditions were tested in order to evaluate possible effects of translation and imagery in the SLT condition. Subjects in the SLT condition performed similarly to subjects in the SPT condition in free recall. Subjects in both these conditions outperformed subjects in the control conditions. The SPT and SLT superiority is suggested to be caused mainly by relevant motor activation.

Adolescent↗

PubMed2002

Circadian clock-related polymorphisms in seasonal affective disorder and their relevance to diurnal preference.

Disturbed circadian rhythms have been observed in seasonal affective disorder (SAD). The aim of this study was to further investigate this connection, and to test for potential association between polymorphisms in circadian clock-related genes and SAD, seasonality (seasonal variations in mood and behavior), or diurnal preference (morningness-eveningness tendencies). A total of 159 European SAD patients and 159 matched controls were included in the genetic analysis, and subsets were screened for seasonality (n=177) and diurnal preference (n=92). We found that diurnal preference was associated with both SAD and seasonality, supporting the hypothesis of a link between circadian rhythms and seasonal depression. The complete case-control material was genotyped for polymorphisms in the CLOCK, Period2, Period3, and NPAS2 genes. A significant difference between patients and controls was found for NPAS2 471 Leu/Ser (chi(2)=9.90, Bonferroni corrected P=0.035), indicating a recessive effect of the leucine allele on disease susceptibility (chi(2)=6.61, Bonferroni corrected P=0.050). Period3 647 Val/Gly was associated with self-reported morningness-eveningness scores (n=92, one-way ANOVA: F=4.99, Bonferroni corrected P=0.044), with higher scores found in individuals with at least one glycine allele (t=3.1, Bonferroni corrected P=0.013). A second, population-based sample of individuals selected for high (n=127) or low (n=98) degrees of seasonality, was also genotyped for NPAS2 471 Leu/Ser. There was no significant difference between these seasonality extreme groups, and none of the polymorphisms studied were associated with seasonality in the SAD case-control material (n=177). In conclusion, our results suggest involvement of circadian clock-related polymorphisms both in susceptibility to SAD and diurnal preference.

Analysis of Variance↗

PubMed2002

Successive memory test performance and priming in Alzheimer's disease: evidence from the word-fragment completion task.

This study assessed the performance of patients with Alzheimer's disease and healthy controls in a successive memory test paradigm. Subjects studied lists of words. Following study, tests of recognition (an explicit memory task) and primed word fragment completion (an implicit memory task) were administered. Since the same words were used in the two tasks, we were able to calculate the degree of dependence between recognition performance and primed word fragment completion. AD patients evidenced impaired recognition memory. In contrast, priming was intact. The pattern of correlation between the two tasks was similar in healthy controls and in AD. Independence between recognition and fragment completion was obtained when recognition preceded the fragment completion task, but not when fragment completion preceded recognition.

Aged↗

PubMed2002

Genetic variation in memory functioning.

On the basis of a review of the literature the contribution of genetic factors for individual differences in memory performance is discussed. Explorations of such influences on memory have just begun. Most of those studies that have been conducted in order to find a quantitative trait locus for memory have focused on ApolipoproteinE (ApoE). One form of this gene is strongly associated with cardiovascular disease in middle age and to late-onset Alzheimer's disease. Some studies have demonstrated an association between ApoE and memory even in non-demented individuals. Other studies have failed to demonstrate this association. Based on data from a prospective cohort study (Betula) in our own laboratory, we have assessed and examined associations between three different forms of ApoE and performance on episodic memory tests. Cross-sectional comparisons revealed non-significant differences in episodic memory performance between carriers of the three alleles. Analyses of change scores in longitudinal data revealed that allele epsilon 4 was related to a lower level of memory performance than alleles epsilon 2 and epsilon 3. This effect was most pronounced in tasks providing cognitive support at both encoding and retrieval, suggesting a deficit in utilizing such support in carriers of the epsilon 4 allele.

Aging↗

PubMed2002

Individual differences in memory enhancement by encoding enactment: relationships to adult age and biological factors.

Numerous studies have demonstrated an age-related decline in episodic memory performance. However, both younger and older adults benefit from various kinds of encoding support, suggesting that memory functioning remains plastic in older age. The present review is concerned with encoding support in the form of enactment. Memory for simple commands is substantially higher if the commands are enacted during encoding than only read/heard. Such memory enhancement has been demonstrated for many age groups and patient groups, suggesting that it is a general effect. Analysis of the results from 1000 participants ranging in age between 35 and 80 years revealed that about 5% of the participants had low memory performance after enacted encoding and showed no enactment effect. The majority of these were older. Comparisons of participants that did or did not show an enactment effect for a select set of biological and neuropsychological factors provided tentative evidence that a failure to benefit from encoding enactment reflects a dysfunctional motor system. This is in agreement with findings from recent functional neuroimaging studies that associate the enactment effect with motor areas in the brain. Variation in the ability to benefit from encoding enactment is discussed in relation to an age-related decline in dopamine function.

Aging↗

PubMed2002

Reference values for serum levels of vitamin B12 and folic acid in a population-based sample of adults between 35 and 80 years of age.

OBJECTIVES: To examine folic acid and vitamin B12 status in a group of 1000 persons sampled from the community of Umeå, Sweden, and aged 35, 40, 45, 50, 55, 60, 65, 70, 75 or 80 years. Reference data for folate and age-stratified reference data for vitamin B12 are presented, together with an examination of potential confounders. MEASUREMENTS: All subjects participated in extensive health examinations and interviews, and laboratory blood testing was performed. RESULTS: A series of exclusion criteria were applied, and data from 961 subjects were analysed. Vitamin B12 levels were found to decrease with increasing age, whereas folate levels remained constant across the age span studied. None of the vitamins was found to vary with sex, education, smoking or alcohol consumption, body mass index, prescription-free vitamin supplements, level of haemoglobin, or mean cell volume of erythrocytes. Further, none of these factors was associated with the age-related decrease of vitamin B12 level. CONCLUSIONS: The offered reference ranges should be used only in order to rule out deficiency. For B12 levels, the age of the subject should be considered such that, for elderly people in particular, values above the medians should be considered as indicative of normal vitamin status.

Adult↗