Biomedical subjects

N L Pedersen

Publications and source records attributed to N L Pedersen.

At least 37 records · Page 2Linked to original sources

PubMed2001

Olfactory functioning and cognitive abilities: a twin study.

A Swedish version of the National Geographic Smell Survey (Wysocki and Gilbert 1989) was completed by 227 twin pairs from the Swedish Adoption/Twin Study of Aging. Twins ranged in age from 45 to 89 years. Quantitative genetic analysis of four measures of olfactory functioning indicated moderate heritability for odor identification and perceived intensity and nonsignificant heritability for odor detection and perceived pleasantness. Bivariate analyses revealed that the relationship between odor identification and measures of verbal ability was primarily genetically mediated. The results provided further support for the hypothesis that odor identification and verbal ability in general tap the same cognitive domain (Larsson 1997).

Aged↗

PubMed2001

Education and the risk of Alzheimer's disease: findings from the study of dementia in Swedish twins.

The association between dementia and education was studied in 143 twin pairs discordant for dementia, using a matched-pair design, and in 221 dementia cases and 442 unrelated controls from the same twin registry, using a case-control design. Low education was defined as 6 years or less of schooling. Case-control analyses with prevalent cases showed low education to be a risk for Alzheimer's disease but not dementia in general. Low education did not significantly predict incident cases. In the matched-pairs analysis, which controls for genetic and other familial influences, differences in education between demented twins and twin partners were not statistically significant. However, for Alzheimer's disease, odds ratios resulting from matched pairs and case-control analyses were similar. Twins' comparative reports about intellectual involvement earlier in their lives suggest a long-standing difference on this dimension, with less involvement by the twin who became demented.

Aged↗

PubMed2001

Deficits in controlled processing may predict dementia: a twin study.

This study tested for differential patterns of cognitive decline in 33 twin pairs for which both were nondemented, but 1 member of the pair went on to develop dementia. Compared with their nondemented twin partners, twins who later developed dementia already showed poorer performance on tests of memory and attention, visuospatial-reasoning skills, and perceptual speed and the Mini-Mental State Examination (MMSE). The authors suggest that this cluster of tests reflects deficits in controlled rather than automatic cognitive processes. Nondemented twin partners of the twins who became demented were also compared with 33 matched controls selected from pairs in which both members remained nondemented. Nondemented twin partners scored lower than matched controls on tests of verbal ability, memory and attention, and perceptual speed and the MMSE. This finding indicates that nondemented twin partners of demented twins are at elevated risk themselves for becoming demented, and further suggests that certain areas of cognition are compromised prior to diagnosis of dementia.

Aged↗

PubMed2001

Genetic probes of three theories of maternal adjustment: I. Recent evidence and a model.

Studies focusing on genetic and social influences on maternal adjustment will illumine mother's marriage, parenting, and the development of psychopathology in her children. Recent behavioral genetic research suggests mechanisms by which genetic and social influences determine psychological development and adjustment. First, heritable, personal attributes may influence individuals' relationships with their family members. These genetically influenced family patterns may amplify the effects of adverse, heritable personal attributes on adjustment. Second, influences unique to siblings may be the most important environmental determinants of adjustment. We derive three hypotheses on maternal adjustment from integrating these findings from genetic studies with other contemporary research on maternal adjustment. First, mother's marriage mediates the influence of her heritable, personal attributes on her adjustment. Second, mother's recall of how she was parented is partially genetically influenced, and both her relationships with her spouse and her child mediate the impact of these genetically influenced representations on her current adjustment. Third, characteristics of mother's spouse are important influences on difference between her adjustment and that of her sister's. These sibling-specific influences are unrelated to mother's heritable attributes. The current article develops this model, and [figure: see text] the companion article describes the Twin Mom Study that was designed to test it as well, as its first findings. Data from this study can illumine the role of family process in the expression of genetic influence and lead to specific family interventions designed to offset adverse genetic influences.

Adaptation, Psychological↗

PubMed2001

Genetic probes of three theories of maternal adjustment: II. Genetic and environmental influences.

This is the first report of the Twin Mom Study, an investigation of three hypotheses concerning influences on maternal adjustment. These hypotheses concern the role of the marital and parent-child relationships in mediating genetic influences on maternal adjustment and on the importance of the mothers' marital partners as a specifiable source of influences on their adjustment not shared with their sisters. The study's sample of 150 monozygotic (MZ) twins and 176 dizygotic (DZ) twins was drawn randomly from the Swedish Twin Registry and is, with some small exceptions, likely to be representative of women in the Swedish population. The sample included the marital partners of these twins and their adolescent children. Self-report and coded videotapes were a source of information about family process. Results reported in this first report focus on comparability of American and Swedish samples on scales measuring psychiatric symptoms, and on an analysis of genetic and environmental influences on nine measures of mothers' adjustment. Results suggest comparability between the US and Sweden. Genetic influences were found for all measures of adjustment, particularly in the psychological manifestations of anxiety and for smoking. The pattern of findings also underscored the importance of influences unique to each sibling within the twin pair, thus focusing attention on the potential role of marital partners in maternal adjustment. Results also suggested that experiences shared by the twin sisters, experiences unrelated to their genetic similarity, may influence their fearfulness and alcohol consumption. Our model did not include these influences and thus must be amended.

Adaptation, Psychological↗

PubMed2001

Genetic and environmental influences on social support in later life: a longitudinal analysis.

The present study assessed the etiology of individual differences in social support over a six-year period. The availability of friend support, family support, and the perceived adequacy of the social support network was assessed three times using identical and same-gender fraternal twins reared together and reared apart from the Swedish Adoption/Twin Study of Aging. Results are based on the pairwise responses at the three occasions of measurement (labeled Q1, Q2, and Q3): 462 pairs at Q1 (assessed October 1984), 474 pairs at Q2 (October 1987), and 431 pairs at Q3 (October 1990). The longitudinal phenotypic correlations (ranging from .49 to .77) indicate that social support is a moderately stable characteristic. Qualitative genetic model-fitting analyses resulted in significant heritability estimates for the social support measures at all three measurement occasions. Results also indicate considerable stability in genetic effects across measurement occasions, with genetic correlations ranging from .65 to .97. Nonshared environmental influences were substantial contributors to social support, but were less stable across the measurement occasions, with correlations ranging from .07 to .52.

Adult↗

PubMed2001

A common hormone-sensitive lipase i6 gene polymorphism is associated with decreased human adipocyte lipolytic function.

Hereditary factors may be involved in the pathogenesis of type 2 diabetes. A polymorphism in the hormone-sensitive lipase (HSL) gene (HSLi6) is associated with obesity and diabetes, although it is unknown whether the polymorphism is functional and thereby influences lipolysis. We genotyped 355 apparently healthy nonobese male and female subjects for the HSLi6 polymorphism. Allele 5 was found to be the most common allele (allele frequency 0.57). In 117 of the subjects, we measured abdominal subcutaneous fat cell lipolysis induced by drugs acting at various steps in the lipolytic cascade. The lipolysis rate induced by norepinephrine isoprenaline (acting on beta-adrenoceptors), forskolin (acting on adenylyl cyclase), and dibutyryl cyclic AMP (acting on HSL) were all decreased by approximately 50% in allele 5 homozygotes, as compared with noncarriers. Heterozygotes showed an intermediate lipolytic rate. The difference in lipolysis rate between genotypes was more pronounced in men than in women. We conclude that allele 5 of the HSLi6 polymorphism is associated with a marked decrease in the lipolytic rate of abdominal fat cells. This may in turn contribute to the development of obesity.

Abdomen↗

PubMed2001

Self-rated health as a predictor of mortality among persons with cardiovascular disease in Sweden.

AIMS: This study analyses the association between cardiovascular diseases with and without drug treatment, self-rated health, and all-cause mortality during a 12-year period. METHODS: Genetic and familial environmental effects were controlled for in subsets of the analyses. Data for these analyses were collected in 1984, 1987, 1990, and 1993 as part of the Swedish Adoption/Twin Study of Aging (SATSA), and through record linkage to mortality data from the National Cause of Death Register through 1996. RESULTS: In multivariate analyses, both cardiovascular disease and low self-rated health were associated with higher mortality. Age, sex, lifestyle, diabetes, respiratory problems, cancer, depression, marital status, and social network were controlled for in the analyses. Furthermore, development of cardiovascular disease and/or drug use is associated with a decline in perceived health and higher mortality rates. The co-twin control analyses suggest that drug-treated cardiovascular disease has a marginal effect on survival beyond the effects of bad self-rated health and genetic liability to a certain survival time. CONCLUSIONS: This study shows that subjective health ratings are important predictors of mortality for persons with cardiovascular disease.

Adult↗

PubMed2000

Are genetic influences on peptic ulcer dependent or independent of genetic influences for Helicobacter pylori infection?

BACKGROUND: Genetic factors play a role or roles in the etiology of peptic ulcer disease and the acquisition of Helicobacter pylori infection. OBJECTIVE: To evaluate the relative importance of genetic and environmental influences as well as the importance of H. pylori on peptic ulcer disease. DESIGN: Cross-sectional study on monozygotic (MZ) and dizygotic (DZ) twins, reared apart or together. PARTICIPANTS: Twins of the subregistry of the Swedish Twin Registry included in the Swedish Adoption/Twin Study of Aging. MEASUREMENTS: Peptic ulcer disease and H. pylori status were assessed in MZ and DZ twin pairs reared apart or together. A total of 258 twin pairs had information regarding H. pylori status and history of peptic ulcer. Helicobacter pylori status was assessed as the presence of anti-H. pylori IgG. RESULTS: The intraclass correlations for peptic ulcer disease for MZ twins reared apart and together and DZ twins reared apart and together were 0.67, 0.65, 0.22, and 0.35, respectively, which indicates that genetic effects are important for liability to peptic ulcer. The correlation coefficient for MZ twins reared apart (0.67) provides the best single estimate of the relative importance of genetic effects (heritability) for variation in liability to peptic ulcer disease, and structural model fitting analyses confirmed this result (heritability, 62%). The cross-twin cross-trait correlations for MZ and DZ twins were examined to determine whether genetic effects for peptic ulcer were shared with or independent of genetic influences for H. pylori. The cross-correlations for MZ and DZ twins were almost identical (0.25 and 0.29, respectively), suggesting that familial environmental rather than genetic influences mediate the association between peptic ulcer disease and H. pylori infection. CONCLUSIONS: Genetic influences are of moderate importance for liability to peptic ulcer disease. Genetic influences for peptic ulcer are independent of genetic influences important for acquiring H. pylori infection.

Adult↗

PubMed2000

Tobacco consumption in Swedish twins reared apart and reared together.

BACKGROUND: Prior studies of twins reared together suggest that regular tobacco use (RTU) is substantially heritable. However, strong social influences on RTU might have biased these results. METHODS: We examine the self-report lifetime history of RTU in members of 778 male-male and female-female twin pairs, raised together and apart, born from 1890 to 1958 and ascertained through the population-based Swedish Twin Registry. RESULTS: In men, the pattern of twin resemblance for RTU suggested both genetic and rearing-environmental effects, which, in the best-fit biometrical model, accounted for 61% and 20% of the variance in liability to RTU, respectively. For women, overall results were hard to interpret, but became clearer when divided by birth cohort. In women born before 1925, rates of RTU were low and twin resemblance was environmental in origin. In later cohorts, rates of RTU in women increased substantially, as did heritability. For women born after 1940, heritability of RTU was similar to that seen in men (63%). CONCLUSIONS: Genetic factors play an important etiologic role in RTU. In women, the impact of genetic factors increased in more recent cohorts, suggesting that, as social restrictions on female tobacco use relaxed over time, heritable influences increased in importance.

Adult↗

PubMed2000

Caseinomacropeptide specifically stimulates exocrine pancreatic secretion in the anesthetized rat.

The effect of caseinomacropeptide (CMP) (the [106-169] fragment of kappa-casein produced during digestion of milk protein), was studied in anesthetized rats using bile diversion for a pure pancreatic juice collection system. Intraduodenal administration of CMP induced a dose-related specific stimulation of pancreatic secretion which was nearly abolished by devazepide, atropine, hexamethonium, vagotomy or perivagal capsaicin pretreatment. Moreover, CMP did not inhibit in vitro trypsin activity. These results demonstrate that CMP is more likely to stimulate pancreatic secretion specifically through cholecystokinin release and activation of a vago-vagal cholinergic reflex loop than by inhibition of luminal trypsin, in anesthetized rats.

Anesthesia↗

PubMed2000

Multivariate models of mixed assortment: phenotypic assortment and social homogamy for education and fluid ability.

Phenotypic assortment is assumed to be the principal mechanism of spouse similarity in most biometrical studies. Other assortment mechanisms, such as social homogamy, may be plausible. Two models are presented that consider phenotypic assortment and social homogamy simultaneously (i.e., mixed assortment), where selective associations between social background factors (Model I) versus selective associations between total environments (Model II) distinguish the models. A series of illustrative analyses was undertaken for education and fluid ability available on a sample of 116 Swedish twin pairs and their spouses. On the basis of several fit criteria Model I was preferred over Model II. Both social homogamy and phenotypic assortment may contribute to spouse similarity for educational attainment and fluid ability. Furthermore, spouse similarity for fluid ability may arise indirectly from social homogamy and phenotypic assortment for educational attainment. Power analyses indicated greater observed power for Model I than Model II. Additional power analyses indicated that considerably more twin-spouse sets would be needed for Model II than Model I, to resolve social homogamy and phenotypic assortment. Effects of misspecification of mechanisms of spouse similarity are also briefly discussed.

Adult↗

PubMed2000

Contribution of age, genes, and environment to the relationship between perceptual speed and cognitive ability.

The aim of this study was to examine genetic influences on cognitive ability in adulthood in the context of the relationship between perceptual speed and cognitive aging. Quantitative genetic analysis of data from the Swedish Adoption/Twin Study of Aging allowed for estimation of the contribution of age, genetic, and environmental effects to the variance in a latent cognitive factor and to the covariance between the cognitive factor and perceptual speed. The sample included 292 pairs of monozygotic and dizygotic twins. both reared together and reared apart, ranging in age from 40 to 84 years. Analysis of components of total variance in the cognitive factor indicated that 90% of the age-related variance in the cognitive factor was shared with perceptual speed and 70% of the genetic variance in the cognitive factor was shared with perceptual speed. The correlation between the speed and cognitive factors was primarily genetically mediated.

Adult↗

PubMed2000

Odor identification: influences of age, gender, cognition, and personality.

The aim of this study was to examine the influences of age, gender, cognitive abilities, and personality styles on odor identification. Participants (N = 532) aged 45-87 years from the Swedish Adoption/Twin Study of Aging were assessed with a Swedish version of the National Geographic Smell Survey. Both detection and identification of olfactory information were impaired with age. Gender had no effect on detection or identification. Hierarchical regressions revealed that proficiency in semantic memory, intensity perception, and personality style (i.e., neuroticism, impulsivity, and lack of assertiveness) were potent predictors for successful odor identification, even when individual variations in chronological age, sex, education, and global cognitive functioning were taken into account.

Age Factors↗

PubMed2000

Quantitative genetic analysis of biobehavioral markers of aging in Swedish studies of adult twins.

OBJECTIVES: This article will examine the generalizability of markers of aging across samples and cultures and the genetic and environmental influences on them. METHODS: As part of two studies, 18 demographic, cognitive, physiological, personality, and behavioral variables were available from 459 twin pairs ranging in age from 40 to 90 years. Twelve markers of aging were identified using stepwise regression. Factor analysis of the markers produced four factors: general knowledge, fluid abilities, cardiovascular functioning, and well-being. RESULTS: Analysis of twin similarity for the factors suggested that genetic and environmental influences varied greatly. Significant age differences in heritability were found for three of the four factors. DISCUSSION: Results indicate one aging theory cannot account for changes in all markers of aging. Aging of various systems occurs as a result of different combinations of genetic and environmental influences.

Adult↗

PubMed2000

Both the environment and genes are important for concentrations of cadmium and lead in blood.

Concentrations of cadmium and lead in blood (BCd and BPb, respectively) are traditionally used as biomarkers of environmental exposure. We estimated the influence of genetic factors on these markers in a cohort of 61 monozygotic and 103 dizygotic twin pairs (mean age = 68 years, range = 49-86). BCd and BPb were determined by graphite furnace atomic absorption spectrophotometry. Variations in both BCd and BPb were influenced by not only environmental but also genetic factors. Interestingly, the genetic influence was considerably greater for nonsmoking women (h(2) = 65% for BCd and 58% for BPb) than for nonsmoking men (13 and 0%, respectively). The shared familial environmental (c(2)) influence for BPb was 37% for men but only 3% for women. The association between BCd and BPb could be attributed entirely to environmental factors of mutual importance for levels of the two metals. Thus, blood metal concentrations in women reflect not only exposure, as previously believed, but to a considerable extent hereditary factors possibly related to uptake and storage. Further steps should focus on identification of these genetic factors and evaluation of whether women are more susceptible to exposure to toxic metals than men.

Aged↗

PubMed2000

Defining discordance in twin studies of risk and protective factors for late life disorders.

In studies that employ matched pair analysis to identify environmental exposures important for a disorder, criteria for discordant pairs are seldom discussed. Yet several assumptions concerning the definition of discordancy may have considerable influence over what results are found. Problems are exacerbated when age of onset for a disorder is late in life. We propose a new set of criteria for defining discordant pairs in studies of dementia, taking into account duration of discordance and competing causes of mortality, and evaluate the consequences of choosing alternative definitions of discordancy.

Age of Onset↗

PubMed2000

Genetic and environmental influences on body fat distribution, fasting insulin levels and CVD: are the influences shared?

Central body fat distribution has been shown to be related to hyperinsulinemia, insulin resistance, hypertriglyceridemia, and atherosclerosis to a greater degree than general obesity. There are known to be both genetic and environmental effects on all components of this clustering. Whether these genetic effects are due to one set of genes in common to the components or whether genetic influences on insulin resistance and/or general/abdominal fatness 'turn on' other genes that affect other components of the syndrome is not clear. We analyzed data from the Swedish Adoption/Twin Study of Aging (60% female; monozygotic = 116, dizygotic = 202; average age 65 years) to determine whether there were genetic and/or environmental factors shared among general body fat distribution, abdominal body fat distribution, fasting insulin levels and cardiovascular disease. We found additive genetic effects in males to be significantly different from those in females with genetic effects accounting for variance in waist-hip ratio (males = 28%; females = 49%), body mass index (males = 58%; females = 73%), fasting insulin levels (FI) (males = 27%; females = 49%), and cardiovascular disease (CVD) (males = 18%; females = 37%). There were also shared genetic and environmental effects among all the variables except CVD, but a majority of the genetic variance for these measures was trait specific.

Abdomen↗