Biomedical subjects

S H Aggen

Publications and source records attributed to S H Aggen.

8 recordsLinked to original sources

PubMed2003

Does the level of family dysfunction moderate the impact of genetic factors on the personality trait of neuroticism?

BACKGROUND: While the family environment can directly influence later risk for psychopathology, dysfunction in the family of origin may also moderate the impact of genetic factors on liability for psychiatric disorders. Can a similar pattern be seen for the personality trait of Neuroticism (N)-which is a risk factor for many psychiatric conditions? METHOD: Our sample of 957 complete female-female twin pairs from a population-based register had measures of self-reported N and multiple reporters (twin, co-twin, mother, father) for family dysfunction (FD). Statistical analysis was conducted by traditional regression analysis and a moderator structural equation twin model operationalized in the computer program Mx. RESULTS: Dividing the sample into quartiles based on increasing levels of FD, the mean of N increased substantially while correlations of N in monozygotic (MZ) and dizygotic (DZ) twins were relatively constant. Regression analyses did not suggest greater twin resemblance for N with increasing levels of FD. The best-fit structural equation model was the standard un-moderated model in which the proportion of variance in N due to genetic (39%) and unique environmental effects (61%) remained constant across values of FD. CONCLUSIONS: Although a false-negative result due to limited power cannot be excluded, these analyses do not support the hypothesis that FD moderates the impact of genetic factors on levels of N.

Family Health↗

PubMed2002

Cannabis use in the last year in a US national sample of twin and sibling pairs.

BACKGROUND: Three prior population-based twin studies, none of which was nationally representative, suggested that both genetic and familial-environmental factors contribute to family resemblance for lifetime cannabis use. We seek to replicate these results in a US national probability sample of twin and sibling pairs examining only last year cannabis use. METHODS: Cannabis use in the last year was assessed by self-report questionnaire. Biometrical twin analyses were performed. RESULTS: Twin and sibling resemblance for last-year cannabis use was substantial, and much higher in monozygotic pairs than in dizygotic and sibling pairs, where levels of resemblance were similar. Modeling suggested that sibling resemblance was due to genetic factors--with a heritability of at least 60% and probably family environmental factors. No evidence was found that cannabis use was influenced by a special twin environment. CONCLUSIONS: Consistent with prior studies, use of cannabis is substantially influenced by genetic factors but family-environment is also possibly of importance.

Adult↗

PubMed2001

Pregnancy and perinatal complications associated with risks for common psychiatric disorders in a population-based sample of female twins.

The association between pregnancy and perinatal complications (PPCs) and risks for adult psychiatric disorders other than psychoses has received relatively limited attention. In this study, we aim to characterize the associations between PPCs and risks for anxiety, affective, substance use, and eating disorders in a population-based sample of twins. Personal interviews were conducted with 1,806 female twin subjects to assess their lifetime history of alcoholism, anorexia nervosa, bulimia nervosa, generalized anxiety disorder, major depression, panic disorder, simple phobias, and social phobias. PPCs were retrospectively assessed at personal interview with the subject's parents. The associations between PPCs and risks for psychiatric disorders are characterized using logistic regression. In this sample of twins, gestational age is associated with a significantly increased risk for anorexia nervosa and pregnancy complications are associated with a significantly increased risk for both anorexia nervosa and bulimia nervosa. Pregnancy and perinatal complications may be associated with an increased risk for eating disorders in women.

Adult↗

PubMed2001

Time, memory and the heritability of major depression.

OBJECTIVE: Although family, twin and adoption studies have suggested that lifetime major depression (MD) is a heritable condition, nearly all these studies have relied for the diagnosis on long-term human memory, which is fallible and potentially biased. Could the estimates of heritability of MD be biased by the well-demonstrated genetic influences on memory? METHODS: Both members of 858 female-female twin pairs from a population-based registry were personally interviewed at least three times over 9 years. The interview assessed a history of depressive onsets and recoveries in the last year to the nearest month. We examine heritability of MD using four recall intervals: last year, last 6 months, last 3 months and current month. RESULTS: Examining the occurrence of one or more depressive episodes across all three interviews, heritabilities of MD (95% CI) for the four time periods were: 0.41 (0.27-0.54), 0.41 (0.26-0.55), 0.35 (0.16-0.52) and 0.34 (0.11-0.55). These heritability estimates did not differ significantly from one another. A similar pattern was found if heritability was assessed for the number of interviews in which criteria for MD were met. CONCLUSION: Modelling results suggest that the heritability of MD was not influenced by the duration of the required recall. Genetic influences on human recall do not appear to contribute substantially to estimated heritability of MD.

Adult↗

PubMed2000

Similarity in saliva cortisol measures in monozygotic twins and the influence of past major depression.

BACKGROUND: Some studies suggest that cortisol may be under genetic control. The aims of our study were to investigate the familial resemblance in morning and evening cortisol secretion as assessed by saliva cortisol and to assess the influence of history of major depression. METHODS: Women for this investigation were selected from an ongoing study in female-female twin pairs ascertained from the Virginia Twin Registry. Telephone screening assured that current inclusion/exclusion criteria were met. Subjects were asked to collect AM samples within 45 min after awakening, and evening samples immediately before bedtime for 14 days. RESULTS: There was a high degree of correlation across weeks in both the AM and PM cortisol values, indicating significant stability across individuals. There was significant correlation between AM and PM cortisol in monozygotic twins. In twins with a history of major depression (n = 30), compared with the twins without past major depression (n = 28), there was a trend towards higher cortisol (p = .056). CONCLUSIONS: These results suggest that around 40-45% of the total variance in salivary cortisol is shared by monozygotic twins. Although the increase in baseline cortisol in twins with a history of major depression is only significant at the trend level, the effect size is comparable to an "in episode" depressed population.

Adult↗

PubMed2000

Sex-specific genetic influences on the comorbidity of alcoholism and major depression in a population-based sample of US twins.

BACKGROUND: Alcoholism and depression frequently co-occur, but the origins of this comorbidity remain uncertain. Most previous family, twin, and adoption studies of these disorders have used cases ascertained through treatment settings, who may differ from cases in epidemiological samples. We studied the importance of genetic influences on risk for lifetime comorbidity of major depression and alcoholism by means of a population-based twin sample. METHODS: Lifetime major depression (MD), alcohol abuse, and alcohol dependence were assessed by structured interview for both members of 3755 twin pairs from the Mid-Atlantic Twin Registry. Pair resemblance was analyzed by means of structural equation models. RESULTS: Individuals with MD were at significantly increased risk for alcohol dependence and for a combined diagnosis of alcohol abuse and/or dependence. History of MD in a twin significantly increased the risk of cotwin alcohol dependence and alcohol abuse and/or dependence among identical male pairs and for alcohol abuse and/or dependence in identical female pairs, but not among male or female fraternal pairs. Results of structural modeling indicate that comorbidity occurs because the genetic and specific environmental sources of liability to MD overlap with those underlying alcohol dependence and alcohol abuse and/or dependence. This overlap was significant only within sex, not across sexes. CONCLUSIONS: In this population-based twin sample, the familial transmission of MD and alcohol dependence was largely disorder specific. Comorbidity appears to be due to sex-specific genetic and environmental risk factors. The factors underlying depression in women do not appear to arise from the same factors underlying alcoholism in men.

Adolescent↗

PubMed1999

Sex differences in the sources of genetic liability to alcohol abuse and dependence in a population-based sample of U.S. twins.

BACKGROUND: There are substantial sex differences in all levels of alcohol involvement among U.S. adults. The goal of this study was to test whether the magnitude and sources of genetic and environmental influences on liability for alcohol abuse and dependence differ for men and women. METHODS: Structured personal interviews were used to assess DSM-III-R- and DSM-IV-defined alcohol abuse and dependence among 5091 male and 4168 female twins (including 1546 identical, 1128 same-sex fraternal, and 1423 opposite-sex pairs) born in Virginia between 1934 and 1974. Twin correlations were analyzed using structural equation modeling. RESULTS: The magnitude of twin-pair resemblance was similar across several definitions of alcoholism and was substantially higher among identical than fraternal pairs. The proportion of population variation in liability attributed to genetic factors was substantial among both women (55-66%) and men (51-56%), and we found little evidence of a role of environmental factors shared by family members. In all definitions studied, we could reject a model that the genetic sources of liability in the two sexes overlap completely. CONCLUSION: In this first population-based study of alcoholism among male and female twins from the U.S., we found that genetic factors play a major role in the development of alcoholism in both sexes, that the magnitudes of genetic influence were equally high for men and women, and that the genetic sources of vulnerability are partially, but not completely, overlapping in men and women.

Adolescent↗

PubMedDate not supplied

Short-term fluctuations in elderly people's sensorimotor functioning predict text and spatial memory performance: The Macarthur Successful Aging Studies.

BACKGROUND: While age-related increases of between-person variability in a variety of cognitive measures are commonly reported in cross-sectional studies, the nature of short-term intraindividual fluctuation in elderly people's performance is relatively unexplored. OBJECTIVE: The goal of the present study is to examine short-term fluctuations in elderly people's sensorimotor functioning and their relations to individual differences in verbal and spatial memory. METHODS: Fluctuations in old adults' (mean = 75.71 years, SD = 6.93 years) sensorimotor performance were investigated by biweekly measurements spanning approximately 7 months. Sensorimotor performance was measured by three walking tasks, including the duration and the number of steps taken to walk a 360-degree circle and to walk 10 feet both at normal and fast pace. Performances of verbal and spatial memory were assessed by weekly measurements of digit memory span, memory for short text and spatial recognition. RESULTS: The magnitude of intraindividual fluctuation in most sensorimotor and memory tasks examined was at least half as great as the level of individual differences across persons. In addition, intraindividual fluctuation in sensorimotor performance is a relatively stable individual attribute, which correlates positively with age and negatively with the levels of sensorimotor, text and spatial memory performance. Although a substantial amount of individual differences in intraindividual fluctuation was shared with mean performance level, variance component and hierarchical regression analyses showed that intraindividual fluctuation in walking steps added significant independent contribution over and above that given by level of performance in predicting text and spatial memory. CONCLUSION: Taking these results together, we suggest that intraindividual fluctuations in elderly people's performance should not be ignored or simply treated as measurement error; rather, they are potentially important empirical variables for understanding sensory and cognitive aging and the nature of intraindividual response variations in general.

Aged↗