Nancy Pedersen - Academia.edu (original) (raw)

Papers by Nancy Pedersen

Research paper thumbnail of Shared and unique genetic and environmental influences on aging-related changes in multiple cognitive abilities

Developmental Psychology, 2014

Aging-related declines occur in many different domains of cognitive function during middle and la... more Aging-related declines occur in many different domains of cognitive function during middle and late adulthood. However, whether a global dimension underlies individual differences in changes in different domains of cognition and whether global genetic influences on cognitive changes exist is less clear. We addressed these issues by applying multivariate growth curve models to longitudinal data from 857 individuals from the Swedish Adoption/Twin Study of Aging, who had been measured on 11 cognitive variables representative of verbal, spatial, memory, and processing speed abilities up to 5 times over up to 16 years between ages 50 and 96 years. Between ages 50 and 65 years scores on different tests changed relatively independently of one another, and there was little evidence for strong underlying dimensions of change. In contrast, over the period between 65 and 96 years of age, there were strong interrelations among rates of change both within and across domains. During this age period, variability in rates of change were, on average, 52% domain-general, 8% domain-specific, and 39% test-specific. Quantitative genetic decomposition indicated that 29% of individual differences in a global domain-general dimension of cognitive changes during this age period were attributable to genetic influences, but some domain-specific genetic influences were also evident, even after accounting for domain-general contributions. These findings are consistent with a balanced global and domain-specific account of the genetics of cognitive aging.

Research paper thumbnail of A Cross-National Self-Report Measure of Depressive Symptomatology

International Psychogeriatrics, 1993

The Center for Epidemiological Studies Depression scale (CES-D) was administered in Swedish to tw... more The Center for Epidemiological Studies Depression scale (CES-D) was administered in Swedish to two representative samples, one aged 84 to 90 (mean = 87), the second aged 29 to 95 (mean = 61). There were both linear and quadratic differences with age: the oldest individuals were highest on depressive symptoms, but younger adults were higher than middle-aged. Dimensions or subscales identified by previous studies were generally replicated, including a sadness and depressed mood factor, a psychomotor retardation and loss of energy factor, and a well-being factor (on which items are reverse-scored to indicate depression). The findings support cross-national use of the CES-D to assess self-reported symptoms of depression in adults and older adults.

Research paper thumbnail of Assessing Age of Dementia Onset

Alzheimer Disease & Associated Disorders, 2005

Research paper thumbnail of Multiple-threshold models for genetic influences on age of onset for Alzheimer disease: Findings in Swedish twins

American Journal of Medical Genetics, 2001

Twin studies of dementia have typically used relatively simple 2 Â 2 contingency tables with one ... more Twin studies of dementia have typically used relatively simple 2 Â 2 contingency tables with one threshold to estimate the relative importance of genetic variance for liability to disease. These designs are inadequate for addressing issues of age at onset, censoring of data, and distinguishing shared environmental effects from age effects. Meyer and Breitner [1998: Am J Med Genet 81:92±97] applied a multiplethreshold model to the NAS-NRC Twin Panel (average age of onset, 63.5 years) and report that additive genetic effects and shared environmental effects account for 37% and 35% of the variation, respectively, in age of onset for Alzheimer disease. We apply a modi®ed version of their model to the Study of Dementia in Swedish Twins (average age of onset, 75 years) and ®nd that genetic effects account for 57%±78% of the variance, whereas shared environmental effects are of no importance. Heritability is lower when thresholds are freely estimated rather than ®xed to the population prevalences. We interpret the ®ndings to suggest that models with free thresholds confound in¯uences on longevity with in¯uences for the disease. Multiple-threshold models, however, do not confound age effects with shared environmental in¯uences.

Research paper thumbnail of Personality and Major Depression

Archives of General Psychiatry, 2006

Prior studies suggest that the personality traits of neuroticism and extroversion may be related ... more Prior studies suggest that the personality traits of neuroticism and extroversion may be related to the liability to major depression (MD). To clarify the magnitude and nature of the association between neuroticism and extroversion and the risk for MD. Longitudinal population-based twin cohort. General community. A total of 20 692 members of same-sex twin pairs from the population-based Swedish Twin Registry who completed a self-report questionnaire assessing neuroticism and extroversion in 1972 and 1973 and were personally interviewed for lifetime history of MD more than 25 years later.Main Outcome Measure Lifetime history of modified DSM-IV MD. Levels of neuroticism strongly predicted the risks for both lifetime and new-onset MD. Twin modeling indicated that the association between neuroticism and MD resulted largely from shared genetic risk factors, with a genetic correlation of +0.46 to +0.47. Levels of extroversion were weakly and inversely related to the risks for lifetime and new-onset MD. This effect disappeared when we controlled for the level of neuroticism. Twin modeling produced similar results. Results from both longitudinal and genetic analyses support the hypothesis that neuroticism strongly reflects the liability to MD. This association arises largely because neuroticism indexes the genetic risk for depressive illness. However, substantial proportions of the genetic vulnerability to MD are not reflected in neuroticism. By contrast, extroversion is only weakly related to risk for MD.

Research paper thumbnail of Personality and Major Depression: A Swedish Longitudinal, Population-Based Twin Study

Archives of General Psychiatry, 2006

Prior studies suggest that the personality traits of neuroticism and extroversion may be related ... more Prior studies suggest that the personality traits of neuroticism and extroversion may be related to the liability to major depression (MD). To clarify the magnitude and nature of the association between neuroticism and extroversion and the risk for MD. Longitudinal population-based twin cohort. General community. A total of 20 692 members of same-sex twin pairs from the population-based Swedish Twin Registry who completed a self-report questionnaire assessing neuroticism and extroversion in 1972 and 1973 and were personally interviewed for lifetime history of MD more than 25 years later.Main Outcome Measure Lifetime history of modified DSM-IV MD. Levels of neuroticism strongly predicted the risks for both lifetime and new-onset MD. Twin modeling indicated that the association between neuroticism and MD resulted largely from shared genetic risk factors, with a genetic correlation of +0.46 to +0.47. Levels of extroversion were weakly and inversely related to the risks for lifetime and new-onset MD. This effect disappeared when we controlled for the level of neuroticism. Twin modeling produced similar results. Results from both longitudinal and genetic analyses support the hypothesis that neuroticism strongly reflects the liability to MD. This association arises largely because neuroticism indexes the genetic risk for depressive illness. However, substantial proportions of the genetic vulnerability to MD are not reflected in neuroticism. By contrast, extroversion is only weakly related to risk for MD.

Research paper thumbnail of P1-233

Alzheimer's & Dementia, 2006

Research paper thumbnail of History of Depression and Other Psychiatric Illness as Risk Factors for Alzheimer Disease in a Twin Sample

Alzheimer Disease & Associated Disorders, 1999

Although case-control studies have found elevated risk for Alzheimer disease (AD) associated with... more Although case-control studies have found elevated risk for Alzheimer disease (AD) associated with a prior psychiatric history, most of the previous research had inadequate controls for familial risk factors. Putative psychiatric risk factors were evaluated for a registry-based sample of 65 twin pairs discordant for AD. Risk ratios were calculated for psychiatric illness at any time and for episodes more than 10 years before dementia onset. Prior psychiatric illness was significantly associated with elevated risk. Most of these cases represented depressive episodes. When analyses were restricted to individuals whose mental illness commenced more than 10 years before dementia onset, the magnitude of the odds ratio decreased markedly. These findings suggest that a history of psychiatric illness, especially depression, may be associated with an elevated risk for AD. In particular, these results are consistent with an interpretation that symptoms of depression and similar complaints represent prodromal phases of dementia.

Research paper thumbnail of A harmonized measure of activities of daily living was a reliable and valid instrument for comparing disability in older people across countries

Journal of Clinical Epidemiology, 2005

Background and Objectives: Our aim was to construct a harmonized measure of activities of daily l... more Background and Objectives: Our aim was to construct a harmonized measure of activities of daily living (ADL) across six countries, and to evaluate the reliability and validity of this measure.

Research paper thumbnail of Research psychologist' roles in the genetic revolution

American Psychologist, 2003

Research paper thumbnail of Long-Term Exposure to Ambient Air Pollution and Mortality Due to Cardiovascular Disease and Cerebrovascular Disease in Shenyang, China

PLoS ONE, 2011

Air pollutants (AP) play a role in subclinical inflammation, and are associated with cardiovascul... more Air pollutants (AP) play a role in subclinical inflammation, and are associated with cardiovascular morbidity and mortality. Metabolic syndrome (MetS) is inflammatory and precedes cardiovascular morbidity and type 2 diabetes. Thus, a positive association between AP and MetS may be hypothesized. We explored this association, (taking into account, pathwayspecific MetS definitions), and its potential modifiers in Swiss adults. We studied 3769 participants of the Swiss Cohort Study on Air Pollution and Lung and Heart Diseases in Adults, reporting at least four-hour fasting time before venepuncture. AP exposures were 10-year mean residential PM 10 (particulate matter <10μm in diameter) and NO 2 (nitrogen dioxide). Outcomes included MetS defined by World Health Organization (MetS-W), International Diabetes Federation (MetS-I) and Adult Treatment Panel-III (MetS-A) using four-and eighthour fasting time limits. We also explored associations with individual components of MetS. We applied mixed logistic regression models to explore these associations. The prevalence of MetS-W, MetS-I and MetS-A were 10%, 22% and 18% respectively. Odds of MetS-W, MetS-I and MetS-A increased by 72% (51-102%), 31% (11-54%) and 18% (4-34%) per 10μg/m 3 increase in 10-year mean PM 10 . We observed weaker associations with NO 2 . Associations were stronger among physically-active, ever-smokers and non-diabetic participants especially with PM 10 (p<0.05). Associations remained robust across various sensitivity analyses including ten imputations of missing observations and exclusion of diabetes cases. The observed associations between AP exposure and MetS were sensitive to MetS definitions. Regarding the MetS components, we observed strongest associations with impaired fasting glycemia, and positive but weaker associations with hypertension and waist-circumference-based obesity. Cardio-metabolic effects of AP may be majorly driven by impairment of glucose homeostasis, and to a less-strong extent, visceral adiposity. Welldesigned prospective studies are needed to confirm these findings.

Research paper thumbnail of Shared and unique genetic and environmental influences on aging-related changes in multiple cognitive abilities

Developmental Psychology, 2014

Aging-related declines occur in many different domains of cognitive function during middle and la... more Aging-related declines occur in many different domains of cognitive function during middle and late adulthood. However, whether a global dimension underlies individual differences in changes in different domains of cognition and whether global genetic influences on cognitive changes exist is less clear. We addressed these issues by applying multivariate growth curve models to longitudinal data from 857 individuals from the Swedish Adoption/Twin Study of Aging, who had been measured on 11 cognitive variables representative of verbal, spatial, memory, and processing speed abilities up to 5 times over up to 16 years between ages 50 and 96 years. Between ages 50 and 65 years scores on different tests changed relatively independently of one another, and there was little evidence for strong underlying dimensions of change. In contrast, over the period between 65 and 96 years of age, there were strong interrelations among rates of change both within and across domains. During this age period, variability in rates of change were, on average, 52% domain-general, 8% domain-specific, and 39% test-specific. Quantitative genetic decomposition indicated that 29% of individual differences in a global domain-general dimension of cognitive changes during this age period were attributable to genetic influences, but some domain-specific genetic influences were also evident, even after accounting for domain-general contributions. These findings are consistent with a balanced global and domain-specific account of the genetics of cognitive aging.

Research paper thumbnail of A Cross-National Self-Report Measure of Depressive Symptomatology

International Psychogeriatrics, 1993

The Center for Epidemiological Studies Depression scale (CES-D) was administered in Swedish to tw... more The Center for Epidemiological Studies Depression scale (CES-D) was administered in Swedish to two representative samples, one aged 84 to 90 (mean = 87), the second aged 29 to 95 (mean = 61). There were both linear and quadratic differences with age: the oldest individuals were highest on depressive symptoms, but younger adults were higher than middle-aged. Dimensions or subscales identified by previous studies were generally replicated, including a sadness and depressed mood factor, a psychomotor retardation and loss of energy factor, and a well-being factor (on which items are reverse-scored to indicate depression). The findings support cross-national use of the CES-D to assess self-reported symptoms of depression in adults and older adults.

Research paper thumbnail of Assessing Age of Dementia Onset

Alzheimer Disease & Associated Disorders, 2005

Research paper thumbnail of Multiple-threshold models for genetic influences on age of onset for Alzheimer disease: Findings in Swedish twins

American Journal of Medical Genetics, 2001

Twin studies of dementia have typically used relatively simple 2 Â 2 contingency tables with one ... more Twin studies of dementia have typically used relatively simple 2 Â 2 contingency tables with one threshold to estimate the relative importance of genetic variance for liability to disease. These designs are inadequate for addressing issues of age at onset, censoring of data, and distinguishing shared environmental effects from age effects. Meyer and Breitner [1998: Am J Med Genet 81:92±97] applied a multiplethreshold model to the NAS-NRC Twin Panel (average age of onset, 63.5 years) and report that additive genetic effects and shared environmental effects account for 37% and 35% of the variation, respectively, in age of onset for Alzheimer disease. We apply a modi®ed version of their model to the Study of Dementia in Swedish Twins (average age of onset, 75 years) and ®nd that genetic effects account for 57%±78% of the variance, whereas shared environmental effects are of no importance. Heritability is lower when thresholds are freely estimated rather than ®xed to the population prevalences. We interpret the ®ndings to suggest that models with free thresholds confound in¯uences on longevity with in¯uences for the disease. Multiple-threshold models, however, do not confound age effects with shared environmental in¯uences.

Research paper thumbnail of Personality and Major Depression

Archives of General Psychiatry, 2006

Prior studies suggest that the personality traits of neuroticism and extroversion may be related ... more Prior studies suggest that the personality traits of neuroticism and extroversion may be related to the liability to major depression (MD). To clarify the magnitude and nature of the association between neuroticism and extroversion and the risk for MD. Longitudinal population-based twin cohort. General community. A total of 20 692 members of same-sex twin pairs from the population-based Swedish Twin Registry who completed a self-report questionnaire assessing neuroticism and extroversion in 1972 and 1973 and were personally interviewed for lifetime history of MD more than 25 years later.Main Outcome Measure Lifetime history of modified DSM-IV MD. Levels of neuroticism strongly predicted the risks for both lifetime and new-onset MD. Twin modeling indicated that the association between neuroticism and MD resulted largely from shared genetic risk factors, with a genetic correlation of +0.46 to +0.47. Levels of extroversion were weakly and inversely related to the risks for lifetime and new-onset MD. This effect disappeared when we controlled for the level of neuroticism. Twin modeling produced similar results. Results from both longitudinal and genetic analyses support the hypothesis that neuroticism strongly reflects the liability to MD. This association arises largely because neuroticism indexes the genetic risk for depressive illness. However, substantial proportions of the genetic vulnerability to MD are not reflected in neuroticism. By contrast, extroversion is only weakly related to risk for MD.

Research paper thumbnail of Personality and Major Depression: A Swedish Longitudinal, Population-Based Twin Study

Archives of General Psychiatry, 2006

Prior studies suggest that the personality traits of neuroticism and extroversion may be related ... more Prior studies suggest that the personality traits of neuroticism and extroversion may be related to the liability to major depression (MD). To clarify the magnitude and nature of the association between neuroticism and extroversion and the risk for MD. Longitudinal population-based twin cohort. General community. A total of 20 692 members of same-sex twin pairs from the population-based Swedish Twin Registry who completed a self-report questionnaire assessing neuroticism and extroversion in 1972 and 1973 and were personally interviewed for lifetime history of MD more than 25 years later.Main Outcome Measure Lifetime history of modified DSM-IV MD. Levels of neuroticism strongly predicted the risks for both lifetime and new-onset MD. Twin modeling indicated that the association between neuroticism and MD resulted largely from shared genetic risk factors, with a genetic correlation of +0.46 to +0.47. Levels of extroversion were weakly and inversely related to the risks for lifetime and new-onset MD. This effect disappeared when we controlled for the level of neuroticism. Twin modeling produced similar results. Results from both longitudinal and genetic analyses support the hypothesis that neuroticism strongly reflects the liability to MD. This association arises largely because neuroticism indexes the genetic risk for depressive illness. However, substantial proportions of the genetic vulnerability to MD are not reflected in neuroticism. By contrast, extroversion is only weakly related to risk for MD.

Research paper thumbnail of P1-233

Alzheimer's & Dementia, 2006

Research paper thumbnail of History of Depression and Other Psychiatric Illness as Risk Factors for Alzheimer Disease in a Twin Sample

Alzheimer Disease & Associated Disorders, 1999

Although case-control studies have found elevated risk for Alzheimer disease (AD) associated with... more Although case-control studies have found elevated risk for Alzheimer disease (AD) associated with a prior psychiatric history, most of the previous research had inadequate controls for familial risk factors. Putative psychiatric risk factors were evaluated for a registry-based sample of 65 twin pairs discordant for AD. Risk ratios were calculated for psychiatric illness at any time and for episodes more than 10 years before dementia onset. Prior psychiatric illness was significantly associated with elevated risk. Most of these cases represented depressive episodes. When analyses were restricted to individuals whose mental illness commenced more than 10 years before dementia onset, the magnitude of the odds ratio decreased markedly. These findings suggest that a history of psychiatric illness, especially depression, may be associated with an elevated risk for AD. In particular, these results are consistent with an interpretation that symptoms of depression and similar complaints represent prodromal phases of dementia.

Research paper thumbnail of A harmonized measure of activities of daily living was a reliable and valid instrument for comparing disability in older people across countries

Journal of Clinical Epidemiology, 2005

Background and Objectives: Our aim was to construct a harmonized measure of activities of daily l... more Background and Objectives: Our aim was to construct a harmonized measure of activities of daily living (ADL) across six countries, and to evaluate the reliability and validity of this measure.

Research paper thumbnail of Research psychologist' roles in the genetic revolution

American Psychologist, 2003

Research paper thumbnail of Long-Term Exposure to Ambient Air Pollution and Mortality Due to Cardiovascular Disease and Cerebrovascular Disease in Shenyang, China

PLoS ONE, 2011

Air pollutants (AP) play a role in subclinical inflammation, and are associated with cardiovascul... more Air pollutants (AP) play a role in subclinical inflammation, and are associated with cardiovascular morbidity and mortality. Metabolic syndrome (MetS) is inflammatory and precedes cardiovascular morbidity and type 2 diabetes. Thus, a positive association between AP and MetS may be hypothesized. We explored this association, (taking into account, pathwayspecific MetS definitions), and its potential modifiers in Swiss adults. We studied 3769 participants of the Swiss Cohort Study on Air Pollution and Lung and Heart Diseases in Adults, reporting at least four-hour fasting time before venepuncture. AP exposures were 10-year mean residential PM 10 (particulate matter <10μm in diameter) and NO 2 (nitrogen dioxide). Outcomes included MetS defined by World Health Organization (MetS-W), International Diabetes Federation (MetS-I) and Adult Treatment Panel-III (MetS-A) using four-and eighthour fasting time limits. We also explored associations with individual components of MetS. We applied mixed logistic regression models to explore these associations. The prevalence of MetS-W, MetS-I and MetS-A were 10%, 22% and 18% respectively. Odds of MetS-W, MetS-I and MetS-A increased by 72% (51-102%), 31% (11-54%) and 18% (4-34%) per 10μg/m 3 increase in 10-year mean PM 10 . We observed weaker associations with NO 2 . Associations were stronger among physically-active, ever-smokers and non-diabetic participants especially with PM 10 (p<0.05). Associations remained robust across various sensitivity analyses including ten imputations of missing observations and exclusion of diabetes cases. The observed associations between AP exposure and MetS were sensitive to MetS definitions. Regarding the MetS components, we observed strongest associations with impaired fasting glycemia, and positive but weaker associations with hypertension and waist-circumference-based obesity. Cardio-metabolic effects of AP may be majorly driven by impairment of glucose homeostasis, and to a less-strong extent, visceral adiposity. Welldesigned prospective studies are needed to confirm these findings.