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Biomedical subjects

N L Pedersen

Publications and source records attributed to N L Pedersen.

119 records · Page 7Linked to original sources
PubMed1986

Sedentary jobs and colon cancer.

The association between physical job activity and colon cancer was examined in a 19-year follow-up study of 1.1 million Swedish men. The relative risk (RR) of colon cancer in men employed in sedentary occupations was estimated at 1.3 (1.2-1.5, 90% confidence interval), with the highest risk for the transverse colon including flexures (RR = 1.6) and the lowest risk for the sigmoid (RR = 1.2). The relative risk for rectal cancer was not elevated. Age, population density, and social class did not confound the relative risk and were controlled for, whereas marital status and geographic region did not. Furthermore, food habits and physical activity during leisure time were examined in the same occupations in another sample and it was judged unlikely that confounding from these factors could explain the association.

Adult↗
PubMed1984

Multivariate analysis of familial and non-familial influences for commonality in drug use.

A multivariate behavioral genetic analysis of common legal drug usage was performed on data from 238 Swedish families. By calculating cross-covariances between parents and offspring for pairs of traits, familial and non-familial correlations were computed to determine the extent to which pairs of measures share the same familial and non-familial influences. Factor analyses resulted in a 3- and a 2-factor solution for the familial and non-familial correlations, respectively. This suggests that familial and non-familial influences for drug usage are structured differently. If replicable, these results also suggest that the phenotypic structure reflects familial factors more than non-familial influences.

Adult↗
PubMed1984

Twin analysis as a potential tool for examining psychosocial factors associated with and preceeding smoking behaviors.

Data from the young cohort of the Swedish Twin Registry are being used in an attempt to describe characteristics which distinguish among current, non- and ex-smokers prior to the development of a smoking habit versus those present after establishment of the habit (or lack of one). With twins as a sample of individuals, the psychosocial variables instability, extroversion, leisure activity, relative weight, alcohol, coffee and psychopharmaceutic drug use were examined jointly as predictors of current smoking status in multiple regression analyses. This phase was intended to replicate and expand upon earlier studies characterizing current, non- and ex-smokers. These analyses were then performed on MZ nonsmoking twin individuals who were classified on the basis of their cotwins' smoking status. Pattern of variation in the psychosocial variables across the groups of nonsmokers were similar to the pattern seen for current, ex- and nonsmokers. Characteristics in MZ nonsmokers which are predictive of their cotwins' smoking status may be interpreted as those present prior to development of a smoking habit. Selected results from these analyses will be presented.

Adult↗
PubMed1984

Swedish early separated twins: identification and characterization.

A sample of twins separated early in life has been identified in the Swedish Twin Registry. When the registry was compiled in 1961 (old cohort) and 1973 (young cohort), one or both members of 961 pairs indicated that they were separated by the age of 10. In May 1979, both members of 698 pairs were alive and were sent a questionnaire concerning the circumstances of separation. Items included reasons and timing of separation, biological relatedness of rearing parents, degree of contact after separation (including whether they lived in the same area, attended the same school, or lived together again), rough measures of selective placement, and current frequency of contact. An attempt was then made to categorize the pairs based on degree of separation. A total of 257 pairs met the criteria: rearing parents of one twin biologically unrelated to rearing parents of the cotwin, twins not living together again after separation, and contact after separation a few times a year or less. As much as 50% were separated by their first birthday, and 80% by the age of five. Various data from the twin registry are presented describing the entire sample of early separated twins as compared to a matched sample of twins reared together.

Adolescent↗
PubMed1983

Factor structure of common drug usage.

The correlated usage of commonly employed, legal drugs was examined in a sample of 377 American and 908 Swedish adults. Measures of alcohol, tranquilizer, sleeping pill, and coffee or tea consumption were submitted to a principal components factor analysis with Varimax rotation. The resultant three factors were characterized by (1) heavy drinking in general and beer consumption specifically (ALCFAC), (2) the use of tranquilizers and sleeping medications (TSFAC) and (3) the consumption of coffee and tea (CTFAC). Factor structure profiles for ALCFAC and TSFAC were more stable than CTFAC across nationalities, sexes, and cohorts. Profiles for Swedish smokers and never-smokers were very similar; for Americans, however, profiles for never-smokers were more similar to Swedish profiles than to those of American smokers. Factor scores were computed to examine the relationship between tobacco use and levels of the factors by means of analysis of variance. In Swedes, ALCFAC and CTFAC levels varied with smoking status, whereas ALCFAC and TSFAC levels with smoking status in Americans.

Alcohol Drinking↗
PubMedDate not supplied

Does genetic variance for cognitive abilities account for genetic variance in educational achievement and occupational status? A study of twins reared apart and twins reared together.

Studies of brothers and twins have shown that about 50 per cent of the variance in educational achievement and 40 per cent of the variance in occupational status reflects between-family variance. About half of the between-family variance for educational achievement and even more for occupational status is due to genetic effects and the remainder is due to sharing the same environment. With data on 35 pairs of male twins reared apart and 56 pairs reared together we investigated the extent to which genetic variance in SES can be attributed to genetic variance for cognitive abilities. For both educational achievement and occupational status there was significant genetic variance both in common with and independent of genetic variance for cognitive abilities. Thus, there are genetic effects contributing to familial similarity for SES that are not the same as those of importance for cognitive abilities. Candidate traits that may account for this remaining genetic variance in SES are personality, interests, or talents not represented in standard cognitive tests.

Achievement↗
PubMedDate not supplied

Genetic and environmental influences for type A-like measures and related traits: a study of twins reared apart and twins reared together.

The relative influences of genetic and environmental factors for Type A-like behaviors and related traits were examined in the Swedish Adoption/Twin Study of Aging. The sample consisted of 99 pairs of monozygotic twins separated at an early age and reared apart, 229 pairs of dizygotic twins reared apart, 160 monozygotic pairs reared together, and 212 dizygotic pairs reared together. The average age of the Swedish Adoption/Twin Study of Aging twins at the time of data collection in 1984 was 58.6 (SD 13.6); 72% of the pairs were over 50 years of age and 60% were female. The Framingham Type A Scale, three descriptors of the Type A behavior pattern (pressure, hard-driving, and ambitious), and measures of hostility and lack of assertiveness were assessed in a mailout questionnaire. Heritability (the proportion of total variance due to genetic effects) was 27%, 28%, 43%, 37%, 20%, and 12%, respectively, for the six measures. The most conservative test of significance indicated significant genetic influence for all but the hostility and assertiveness scales. Sharing the same rearing environment was generally unimportant for twin similarity in the Type A behaviors later in life; however, 20% of the variation in the hostility and assertiveness measures could be attributed to shared family environment. Evidence for the effects of correlated post-rearing environments was found for hostility. Approximately 60% of the variation in each of the measures can be attributed to non-shared environmental experiences unique to the individual.

Arousal↗
PubMedDate not supplied

Neuroimaging findings in twins discordant for Alzheimer's disease.

Data from computed tomography (CT) scans of 12 twin pairs in which one partner had Azheimer's disease (AD) and the other partner is cognitively intact were analyzed to study structural brain features associated with AD while controlling for familial factors. Visual ratings and analysis of quantified areas and volumes indicated that AD twins showed more dilation of temporal horns, lateral ventricles and third ventricle, and more atrophy of temporal lobes, particularly in the anterior temporal/perisylvian area, than their healthy cotwins. Demented twins did not have smaller intracranial areas or overall brain volumes than their intact partners. The apolipoprotein sigma-4 allele was associated with greater dilation of lateral ventricles and ventricular volume. Significant intrapair correlations were found for total intracranial area and volume, cerebellar area and white matter lesions.

Aged↗