Biomedical subjects

Lars-Göran Nilsson

Publications and source records attributed to Lars-Göran Nilsson.

45 records · Page 3Linked to original sources

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↗

PubMedDate not supplied

High prevalence of white matter hyperintensities in normal aging: relation to blood pressure and cognition.

The occurrence of cerebral white matter hyperintensities (WMHs), and their associations with blood pressure, episodic memory, and other cognitive tasks, were examined in a population-based sample of 123 individuals between 64 and 74 years old. Magnetic Resonance Imaging (MRI) detected subcortical and periventricular hyperintensities in 90% and 67% of the cases, respectively. Subcortical WMHs were related to elevated diastolic blood pressure measured ten years earlier, and periventricular WMHs were related to elevated diastolic blood pressure measured five and ten years earlier. Subcortical hyperintensities were weakly associated with impaired motor speed, but this association was not significant. Periventricular WMHs had a negative effect on episodic memory, although the relation was not linear. Collectively, the notion that white matter hyperintensities impair cognitive function got weak support in this Swedish sample.

Aged↗

PubMedDate not supplied

Sex differences in cognition are stable over a 10-year period in adulthood and old age.

Sex differences in declarative memory and visuospatial ability are robust in cross-sectional studies. The present longitudinal study examined whether sex differences in cognition were present over a 10-year period, and whether age modified the magnitude of sex differences. Tests assessing episodic and semantic memory, and visuospatial ability were administered to 625 nondemented adults (initially aged 35-80 years), participating in the population-based Betula study at two follow-up occasions. There was stability of sex differences across five age groups and over a 10-year period. Women performed at a higher level than men on episodic recall, face and verbal recognition, and semantic fluency, whereas men performed better than women on a task-assessing, visuospatial ability. Sex differences in cognitive functions are stable over a 10-year period and from 35 to 90 years of age.

Adult↗

PubMedDate not supplied

Verified hormone therapy improves episodic memory performance in healthy postmenopausal women.

Studies of hormone therapy (HT) and cognition have yielded conflicting results. The aim of this observational study was to examine the effect of estradiol, via serum verified HT (estradiol, estriol, progesterone) and endogenous estradiol, on 108 healthy postmenopausal women's cognitive performance. The results demonstrated that the 43 HT-users performed at a significantly higher level than non-users on episodic memory tasks and on a verbal fluency task, whereas HT-users and non-users did not differ on tasks assessing semantic memory and spatial visualization. In addition, there was a positive relationship between serum estradiol level and episodic memory performance, indicating that postmenopausal HT is associated with enhanced episodic memory and verbal fluency, independent of age and education. These observational results suggest that HT use may be sufficient to exert small, yet positive effects on female sensitive cognitive tasks. Hormone therapy compliance and formulation is discussed as confounding factors in previous research.

Analysis of Variance↗