Introduction and evaluation of a novel multi-camera surface topography system

BACKGROUND

Surface topography can be used for the evaluation of spinal deformities without any radiation. However, so far this technique is limited to posterior trunk measurements due to the use of a single posterior camera.

RESEARCH QUESTION

Purpose of this study was to introduce a new multi camera surface topography system and to test its reliability and validity.

METHODS

The surface topograph uses a two-camera system for imaging and evaluating the subjects front and back simultaneously. Inter- and intra-rater reliability was tested on 40 human subjects by two observers. For validation human, subjects were scanned by MRI and surface-topography. For additional validation we used a phantom with an anthropomorphic body which was scanned by CT and surface topography.

RESULTS

Inter- (0.97-0.99) and intra-rater reliability (0.81-0.98) testing revealed good and excellent results in the detection of the body surface structures and measurement of areas and volumes. CT based validation revealed good correspondence between systems in the imaging and evaluation of the phantom model (0.61-10.52 %). Results on validation of human subjects revealed good to moderate results in the detection and measurements of almost all body surface structures (1.36-13.34 %). Only measurements using jugular notch as a reference showed moderate results in validity (0.62-27.5%) testing.

SIGNIFICANCE

We have introduced a novel and innovative surface topography system that allows for simultaneous anterior and posterior trunk measurements. The results of our reliability and validity tests are satisfactory. However, in particular around the jugular notch region further improvements in the surface topography reconstruction are needed.

Development of a new 360-degree surface topography application

BACKGROUND

Surface-topography has been used for almost two decades in the radiation-free clinical evaluation of spinal posture. So far, it was limited to the analysis of back surface and spine. In order to better understand, diagnose and treat complex spinal pathologies, it is important to measure the whole torso.

RESEARCH QUESTION

Purpose of this study was to introduce and test an application that allows 360° reconstruction and analysis of the patient's torso.

METHODS

The application uses the information gathered from eight distinct scans and angles. For validation we used an Alderson phantom as an anthropomorphic body. Defined areas and volumes were measured by CT and surface-topography. Inter- and intra-rater reliability was tested in 35 healthy subjects by two observers.

RESULTS

The results revealed good correspondence between systems in the imaging and evaluation of the Alderson model (5.3-0.5%). Inter- (0.9-0.98) and intra-rater reliability (0.8-0.95) testing revealed good and excellent results in the detection of almost all body surface structures and measurement of areas and volumes. Only area and volume measurements using jugular notch as a reference showed partly moderate results in reliability (0.62-0.93) testing.

SIGNIFICANCE

We were able to introduce a novel 360° torso scan application using surface topography to reconstruct torso measurements. The results of our study showed its high validity and reliability. In the future, this application needs to be tested in patients with spinal pathologies. In summary, this new application may help to better understand, diagnose and treat patients with pathologies of torso and spine.

Comparison of two different designs of forefoot off-loader shoes and their influence on gait and spinal posture

BACKGROUND

The purpose of forefoot off-loader shoes (FOS) is to unload the operated region of the foot in order to allow early mobilization and rehabilitation. However, little is known about the actual biomechanical effects of different designs of FOS on gait, pelvis and spine.

RESEARCH QUESTION

Aim of this study was to analyse and compare the effects of two different designs of forefoot unloader shoes.

METHODS

Ortho-Wedge (FOS A) and Relief-Dual® (FOS B) were evaluated in this study during standing and while walking. Changes of the pelvic position and spinal posture were measured with a surface topography system and an instrumented treadmill. Gait phases were detected automatically by a built-in pressure plate.

RESULTS

Both FOS resulted in a significant increase of pelvic obliquity, pelvic torsion, lateral deviation and surface rotation (p < 0.001) while standing. Between both shoe models, pelvic obliquity and lateral deviation (p < 0.05) were significantly different. During walking, both FOS had a significant effect on spine and pelvis (p < 0.05), however only minor differences were found between the designs. All gait parameters were affected more, wearing FOS A than B. Step length were significantly longer by wearing FOS (p < 0.005). However stance phase raised and swing phase is reduced on the leg wearing FOS A (p < 0.001).

SIGNIFICANCE

The study showed that FOS lead to significant changes in pelvic position and spinal posture during standing and while walking. A compensating shoe on the contralateral side is therefore recommend. Gait parameters however were affected more by the traditional FOS A half-shoe. The sole- design and shape of FOS B leads to a more physiological roll-over of the foot.

Gene-environment interplay in depressive symptoms: moderation by age, sex, and physical illness

BACKGROUND

Numerous factors influence late-life depressive symptoms in adults, many not thoroughly characterized. We addressed whether genetic and environmental influences on depressive symptoms differed by age, sex, and physical illness.

METHOD

The analysis sample included 24 436 twins aged 40-90 years drawn from the Interplay of Genes and Environment across Multiple Studies (IGEMS) Consortium. Biometric analyses tested age, sex, and physical illness moderation of genetic and environmental variance in depressive symptoms.

RESULTS

Women reported greater depressive symptoms than men. After age 60, there was an accelerating increase in depressive symptom scores with age, but this did not appreciably affect genetic and environmental variances. Overlap in genetic influences between physical illness and depressive symptoms was greater in men than in women. Additionally, in men extent of overlap was greater with worse physical illness (the genetic correlation ranged from near 0.00 for the least physical illness to nearly 0.60 with physical illness 2 s.d. above the mean). For men and women, the same environmental factors that influenced depressive symptoms also influenced physical illness.

CONCLUSIONS

Findings suggested that genetic factors play a larger part in the association between depressive symptoms and physical illness for men than for women. For both sexes, across all ages, physical illness may similarly trigger social and health limitations that contribute to depressive symptoms.

Genetic susceptibility to cardiovascular disease and risk of dementia

Several studies have shown cardiovascular disease (CVD) to be associated with dementia, but it is not clear whether CVD per se increases the risk of dementia or whether the association is due to shared risk factors. We tested how a genetic risk score (GRS) for coronary artery disease (CAD) affects dementia risk after CVD in 13 231 Swedish twins. We also utilized summarized genome-wide association data to study genetic overlap between CAD and Alzheimer´s disease (AD), and additionally between shared risk factors and each disease. There was no direct effect of a CAD GRS on dementia (hazard ratio 0.99, 95% confidence interval (CI): 0.98-1.01). However, the GRS for CAD modified the association between CVD and dementia within 3 years of CVD diagnosis, ranging from a hazard ratio of 1.59 (95% CI: 1.05-2.41) in the first GRS quartile to 1.91 (95% CI: 1.28-2.86) in the fourth GRS quartile. Using summary statistics, we found no genetic overlap between CAD and AD. We did, however, find that both AD and CAD share a significant genetic overlap with lipids, but that the overlap arose from clearly distinct gene clusters. In conclusion, genetic susceptibility to CAD was found to modify the association between CVD and dementia, most likely through associations with shared risk factors.

Particulate air pollutants, APOE alleles and their contributions to cognitive impairment in older women and to amyloidogenesis in experimental models

Exposure to particulate matter (PM) in the ambient air and its interactions with APOE alleles may contribute to the acceleration of brain aging and the pathogenesis of Alzheimer's disease (AD). Neurodegenerative effects of particulate air pollutants were examined in a US-wide cohort of older women from the Women's Health Initiative Memory Study (WHIMS) and in experimental mouse models. Residing in places with fine PM exceeding EPA standards increased the risks for global cognitive decline and all-cause dementia respectively by 81 and 92%, with stronger adverse effects in APOE ɛ4/4 carriers. Female EFAD transgenic mice (5xFAD+/-/human APOE ɛ3 or ɛ4+/+) with 225 h exposure to urban nanosized PM (nPM) over 15 weeks showed increased cerebral β-amyloid by thioflavin S for fibrillary amyloid and by immunocytochemistry for Aβ deposits, both exacerbated by APOE ɛ4. Moreover, nPM exposure increased Aβ oligomers, caused selective atrophy of hippocampal CA1 neurites, and decreased the glutamate GluR1 subunit. Wildtype C57BL/6 female mice also showed nPM-induced CA1 atrophy and GluR1 decrease. In vitro nPM exposure of neuroblastoma cells (N2a-APP/swe) increased the pro-amyloidogenic processing of the amyloid precursor protein (APP). We suggest that airborne PM exposure promotes pathological brain aging in older women, with potentially a greater impact in ɛ4 carriers. The underlying mechanisms may involve increased cerebral Aβ production and selective changes in hippocampal CA1 neurons and glutamate receptor subunits.

Midlife overweight and obesity increase late-life dementia risk: a population-based twin study

OBJECTIVE

The relation of overweight to dementia is controversial. We aimed to examine the association of midlife overweight and obesity with dementia, Alzheimer disease (AD), and vascular dementia (VaD) in late life, and to verify the hypothesis that genetic and early-life environmental factors contribute to the observed association.

METHODS

From the Swedish Twin Registry, 8,534 twin individuals aged ≥65 (mean age 74.4) were assessed to detect dementia cases (DSM-IV criteria). Height and weight at midlife (mean age 43.4) were available in the Registry. Data were analyzed as follows: 1) unmatched case-control analysis for all twins using generalized estimating equation (GEE) models and 2) cotwin matched case-control approach for dementia-discordant twin pairs by conditional logistic regression taking into account lifespan vascular disorders and diabetes.

RESULTS

Among all participants, dementia was diagnosed in 350 subjects, and 114 persons had questionable dementia. Overweight (body mass index [BMI] >25-30) and obesity (BMI >30) at midlife were present in 2,541 (29.8%) individuals. In fully adjusted GEE models, compared with normal BMI (20-25), overweight and obesity at midlife were related to dementia with odds ratios (ORs) (95% CIs) of 1.71 (1.30-2.25) and 3.88 (2.12-7.11), respectively. Conditional logistic regression analysis in 137 dementia-discordant twin pairs led to an attenuated midlife BMI-dementia association. The difference in ORs from the GEE and the matched case-control analysis was statistically significant (p = 0.019).

CONCLUSIONS

Both overweight and obesity at midlife independently increase the risk of dementia, AD, and VaD. Genetic and early-life environmental factors may contribute to the midlife high adiposity-dementia association.

Overweight in midlife and risk of dementia: a 40-year follow-up study

OBJECTIVE

This study examines whether overweight in midlife increases dementia risk later in life.

METHODS

In 1963 body mass index was assessed in 1152 participants of The Swedish Twin Registry, at the age of 45-65 years. These participants were later screened for dementia in a prospective study with up to 40 years follow-up. A total of 312 participants were diagnosed with dementia.

RESULTS

Logistic regression analyses adjusted for demographic factors, smoking and alcohol habits, indicated that men and women categorized as overweight in their midlife had an elevated risk of dementia (OR=1.59; 95% CI: 1.21-2.07, P=0.002), Alzheimer's disease (OR=1.71; 95% CI: 1.24-2.35, P=0.003), and vascular dementia (OR=1.55; 95% CI: 0.98-2.47, P=0.059). Further adjustments for diabetes and vascular diseases did not substantially affect the associations, except for vascular dementia (OR=1.36; 95% CI: 0.82-2.56, P=0.116), reflecting the significance of diabetes and vascular diseases in the etiology of vascular dementia. There was no significant interaction between overweight and APOE epsilon4 status, indicating that having both risk factors does not have a multiplicative effect with regard to dementia risk.

CONCLUSIONS

This study gives further support to the notion that overweight in midlife increases later risk of dementia. The risk is increased for both Alzheimer's disease and vascular dementia, and follows the same pattern for men and women.

Clinical indices of familial depression in the Swedish Twin Registry

OBJECTIVE

Although familial factors certainly contribute to the etiology of major depression (MD), further information is needed about which clinical features of depressive illness index the familial vulnerability in MD.

METHOD

Lifetime MD and associated clinical features were assessed at personal interview in 27 230 individual twins, including 4080 onsets of MD, from the Swedish National Twin Registry. Analyses were conducted using Cox proportional hazards models.

RESULTS

Three clinical variables in a depressed twin predicted the hazard ratio for MD in the cotwin. In the order of the strength of the association, these were: number of endorsed A criteria, age at onset, and number of episodes.

CONCLUSION

Certain clinical features of MD are significant, albeit modest, indices of the familial vulnerability to MD. Individuals with a high familial/genetic risk for MD tend to have an early age at onset, meet most of the symptomatic DSM criteria and suffer recurrences.

Women, Co-occurring Disorders, and Violence Study: Evaluation design and study population

The Women, Co-occurring Disorders, and Violence Study (WCDVS) was a multi-site cooperative study to evaluate new service models for women with co-occurring mental health and substance use disorders and a history of physical and/or sexual abuse. Despite common features in the service interventions and evaluation procedures, diversity across the nine sites plus differences introduced by non-random assignment led to numerous methodological challenges. This article describes the design, measurement, and analysis decisions behind the WCDVS and lays the foundation for understanding participant-level outcomes and service costs. This article also describes the study population, as recruited and following attrition at the 6-month follow-up, in order to address the threat of selection bias to inferences drawn from this multi-site study.

Gender differences in heritability of depressive symptoms in the elderly

BACKGROUND

The present study aimed to investigate the relative importance of genetic and environmental influences on depressive symptoms in the elderly.

METHOD

Depressive symptoms were assessed through the Center for Epidemiological Studies-Depression (CES-D) scale. The CES-D scale was administered to 959 twin pairs (123 female MZs, 90 male MZs, 207 same-sex female DZs, 109 same-sex male DZs and 430 opposite-sex DZs) aged 50 years or older (mean age 72 years). A dichotomous depressed state variable was constructed based on CES-D cut-offs and self-reported use of antidepressant medication. Structural equation models were fitted to the data to dissect genetic and environmental variance components.

RESULTS

The sex-specific heritability estimates for depressive symptoms were 14% for males and 29% for females and 23% when constrained to be equal for men and women. The prevalence of clinically significant depressive symptoms was 16% for men and 24% for women. Heritability estimates for the dichotomous depressed state measure were 7% for males and 49% for females in the full model and 33% when constrained to be equal.

CONCLUSION

Our results suggest that depressive symptoms in the elderly are moderately heritable, with a higher heritability for women than men, although differences in heritability estimates were not statistically significant.

Association between depressed mood in the elderly and a 5-HTR2A gene variant

The aim of this study was to investigate any possible association between depressed mood in the elderly and two candidate SNPs in the serotonin system: one in the 5-HTR2A gene promotor (-1438 G/A) and one in the 5-HT transporter gene (-925 C/A). DNA from a population-based Swedish twin sample (N = 1,592; mean age = 73) was genotyped using Pryosequencing trade mark. An association was found between the 5-HTR2A gene promotor polymorphism and depressed mood (OR: 1.5, CI: 1.1-2.1) for the A/A genotype in the total sample. When the sample was analyzed by gender, a significant association (OR: 2.4, CI: 1.4-4.4) was found for males and the A/A genotype, but not for females. The 5-HT transporter gene was not associated with depressed mood in this elderly population. These results suggest that there might be different genetic mechanisms for males and females contributing to the development of depressed mood in the elderly.

Multiple-threshold models for genetic influences on age of onset for Alzheimer disease: findings in Swedish twins

Twin studies of dementia have typically used relatively simple 2 x 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 multiple-threshold 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 modified version of their model to the Study of Dementia in Swedish Twins (average age of onset, 75 years) and find 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 fixed to the population prevalences. We interpret the findings to suggest that models with free thresholds confound influences on longevity with influences for the disease. Multiple-threshold models, however, do not confound age effects with shared environmental influences.

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.

A longitudinal analysis of anxiety and depressive symptoms

The authors modeled depressive and anxiety symptom data from 1,391 participants in a longitudinal study of middle-aged and older Swedish twins (M age = 60.9 years, SD = 13.3). Although anxiety and depression were highly correlated, a model with distinct Anxiety and Depression factors fit the data better than models with Positive and Negative Affect factors or a single Mental Health factor. Lack of well-being was associated with anxiety rather than depression. Over two 3-year intervals, anxiety symptoms led to depressive symptoms, but the relationship was not reciprocal. Anxiety symptoms were more stable than depression. These findings provide additional support for the idea that anxiety symptoms may reflect a personality trait such as neuroticism more than do depressive symptoms and suggest that low positive affect may not be as specific to depression among older adults as in younger people.

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.

A longitudinal analysis of anxiety and depressive symptoms

The authors modeled depressive and anxiety symptom data from 1,391 participants in a longitudinal study of middle-aged and older Swedish twins (M age = 60.9 years, SD = 13.3). Although anxiety and depression were highly correlated, a model with distinct Anxiety and Depression factors fit the data better than models with Positive and Negative Affect factors or a single Mental Health factor. Lack of well-being was associated with anxiety rather than depression. Over two 3-year intervals, anxiety symptoms led to depressive symptoms, but the relationship was not reciprocal. Anxiety symptoms were more stable than depression. These findings provide additional support for the idea that anxiety symptoms may reflect a personality trait such as neuroticism more than do depressive symptoms and suggest that low positive affect may not be as specific to depression among older adults as in younger people.

Symptoms of depression in the oldest old: a longitudinal study

This study examined depressive symptoms in a population-based, longitudinal sample of people aged 80 and older to determine initial prevalence of depressive symptoms and changes over time. Depressive symptomatology was assessed with the Center for Epidemiologic Studies-Depression scale (CES-D). The sample was drawn from the OCTO-Twin study, which examined 702 Swedish twins over age 80 in which both members of the pair were still surviving. For the present study, one member of each twin pair was randomly selected, resulting in a sample of 351. A comprehensive biobehavioral assessment was conducted at three time points over 4 years. Depressive symptoms were initially relatively low and decreased significantly between Wave 1 and Wave 2. At Wave 3, depressive symptoms increased slightly but not significantly. Participants who received a dementia diagnosis at some point in the study did not differ significantly on initial CES-D scores when compared to those participants who never received such a diagnosis. Lack of well-being, as opposed to negative affect, was the biggest contributor to the overall depression score at each of the three waves of measurement. Predictors of negative affect for this sample included activities of daily living, subjective health, and performance on the cognitive test, block design. None of these predictors were significant for lack of well-being.

Age-related differences and change in positive and negative affect over 23 years

Positive and negative affect, measured by the Bradburn Affect Balance Scale, were studied in a longitudinal sample spanning from 1971 to 1994. The sample (N = 2,804) represented 4 generations of families. Linear trend analyses compared generations over time for positive and negative affect and also examined the possible influences of neuroticism and extraversion on initial levels of affect and patterns of change in affect. Negative affect decreased with age for all generations, although the rate was attenuated among the oldest adults. Higher neuroticism scores also attenuated the decrease in negative affect across time. For positive affect, the younger and middle-aged adults showed marked stability, but the older group evidenced a small decrease over time. Higher levels of extraversion were related to more stability in positive affect.

Age and emotional response to the Northridge earthquake: a longitudinal analysis

Cross-sectional studies have found older adults to have lower levels of emotional distress after natural disasters. The maturation hypothesis suggests that older adults are less reactive to stress events, whereas the inoculation hypothesis argues that prior experience with disaster is protective. One hundred and sixty-six adults aged 30 to 102 were interviewed regarding the 1994 Northridge earthquake. Longitudinal data were available on depressed mood before and after the earthquake. The maturation hypothesis was generally not supported. The young-old were least depressed; however, this age difference was present prior to the earthquake. The old-old showed lowest levels of earthquake-specific rumination, but age did not buffer the relationship between damage exposure and rumination. The inoculation hypothesis was supported for depressed mood. Prior earthquake experience was related to lower postearthquake depression scores.

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.

Psychosocial interventions for individuals with dementia: an integration of theory, therapy, and a clinical understanding of dementia

We reviewed six psychosocial interventions for individuals with dementia. Interventions are described in terms of theoretical basis, how knowledge about dementia is incorporated, techniques, and empirical support. Psychodynamic approaches appear helpful for understanding intrapsychic concerns of demented individuals. Support groups and cognitive/behavioral therapy assist early stage individuals to build coping strategies and reduce distress. Reminiscence and life review provide mild to moderate stage individuals with interpersonal connections. Behavioral approaches and memory training target specific cognitive and behavioral impairments and help to optimize remaining abilities. Reality orientation reflects a similar goal, yet is probably more useful for its interpersonal functions.

Dexamethasone pharmacokinetics in the inner ear: comparison of route of administration and use of facilitating agents

There is growing otologic interest in treating inner ear disorders, such as sudden sensorineural hearing loss and acute or unremitting Meniere's disease, with intratympanic dexamethasone (IT-DEX). Although anecdotally reported, there are no scientific clinical papers and few prior laboratory research publications on the subject. This study compares perilymph dexamethasone concentrations after systemic and intratympanic administration and assesses the role of 3 potential transport facilitators of IT-DEX into perilymph. Forty guinea pigs (79 ears) were randomly separated into 5 groups. Dexamethasone levels were measured by radioimmunoassay. IT-DEX resulted in higher perilymph steroid levels than intravenous dexamethasone (P < 0.05). Histamine facilitator resulted in significantly higher perilymph steroid levels than IT-DEX alone (P < 0.05). Neither hyaluronic acid nor dimethylsulfoxide was a potent facilitator. This study demonstrates that IT-DEX administration results in superior perilymph levels within 1 hour of administration and does not result in systemic absorption. Histamine is a potent facilitating agent. The clinical implications are considerable.

Genetic and behavioral risk factors for self-reported joint pain among a population-based sample of Swedish twins

Self-reported joint pain, a typical manifestation of osteoarthritis, was examined using 335 twin pairs from the Swedish Adoption/Twin Study of Aging to estimate relative genetic and environmental influences on self-reported joint pain and to examine the relationships between joint pain, health behavior, and psychological variables. Findings suggest that family resemblance for self-reported joint pain represents similar environments more than genetic similarity. Data from the early 1970s, including exercise, physical activity at work, obesity, and neuroticism, were used to predict joint pain in 1993. For men, moderate amounts of exercise decreased the likelihood of joint pain, but strenuous amounts of physical activity in the workplace had the opposite effect. For women, exercise and physical activity were not significant predictors, but past obesity and higher levels of neuroticism increased the likelihood of reporting joint pain in 1993.

Genetic and behavioral risk factors for self-reported joint pain among a population-based sample of Swedish twins

Self-reported joint pain, a typical manifestation of osteoarthritis, was examined using 335 twin pairs from the Swedish Adoption/Twin Study of Aging to estimate relative genetic and environmental influences on self-reported joint pain and to examine the relationships between joint pain, health behavior, and psychological variables. Findings suggest that family resemblance for self-reported joint pain represents similar environments more than genetic similarity. Data from the early 1970s, including exercise, physical activity at work, obesity, and neuroticism, were used to predict joint pain in 1993. For men, moderate amounts of exercise decreased the likelihood of joint pain, but strenuous amounts of physical activity in the workplace had the opposite effect. For women, exercise and physical activity were not significant predictors, but past obesity and higher levels of neuroticism increased the likelihood of reporting joint pain in 1993.

Application of life table analysis to the onset of dementia in a genetically informative design

The primary objective of this study was to estimate the survival function for time to onset of dementia in initially unaffected twins from when their partner (index proband) was diagnosed with dementia of the Alzheimer's type. Survival functions generated by life table analyses were compared by zygosity and gender. Sixty-one twin pairs where at least one member had been diagnosed with dementia of Alzheimer's type were included in the analyses. Additionally, both members of the twin pair had to be alive at the time the index proband was diagnosed with dementia. The probability of remaining cognitively intact within the first three years after the proband was diagnosed was high (0.93, 95% CI 0.89, 1.0), but after 15 years the probability of remaining intact was low (0.34, 95% CI 0.16, 0.52). Age of onset of the index proband was a significant covariate in the survival functions. There were significant differences in the survival functions for monozygotic (MZ) and dizygotic (DZ) co-twins (chi2 = 3.86, 1, P < 0.05), evidencing a genetic component for age of onset for dementia, but there were no significant differences between men and women.

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.

History of depression and other psychiatric illness as risk factors for Alzheimer disease in a twin sample

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.

[Genetic factors are often found inl Alzheimer disease. An extensive twin study to clarify the heredity-environment relationship]

Genetic and environmental risk factors are central concerns in dementia research. Through twin studies one can study the relative importance of genetic and environmental risk factors. One such study, based on the Swedish Twin Registry, shows that genetic effects are of considerable importance for developing Alzheimer's disease, even late in life, but that environmental factors are also important. For vascular dementia, the results indicate that non-genetic factors are of primary importance.

A twin study of mortality after spousal bereavement

BACKGROUND

Previous research has shown an increased risk of mortality after spousal bereavement, with the highest risk in the first weeks or months closest to the loss. One difficult issue in these designs is appropriate covariates and control groups.

METHOD

This study is based on 1993 pairs of twins discordant for marital status and on 35860 married individuals from the Swedish Twin Registry born between 1886 and 1958 and followed for marital and vital status between 1981 and 1993.

RESULTS

Spousal bereavement was a risk factor for mortality for both men and women using the still married co-twin as a control to the widowed proband, and controlling for earlier health status and health-related risk factors. The mortality risk was higher for young-old (under 70 years) individuals, and for recently widowed than for longer-term widowed. Young-old women had a pattern with increased mortality risk during the first years after bereavement, but also a markedly decreased risk if they survived 4 years after bereavement, as compared to married women.

CONCLUSIONS

The results support a causal effect of bereavement on mortality. The decrease in risk for long-term young-old women is congruent with reports by widows of psychological growth after bereavement, involving increased sense of mastery and competence after learning to live in new sets of circumstances following the loss of their husband.

Dementia and occupational exposure to magnetic fields

OBJECTIVES

The purpose of the present report was to assess whether occupational magnetic field exposure is a risk factor for dementia, in particular for Alzheimer's disease.

METHODS

Case-control analyses were applied to 77 dementia cases, 55 of whom had Alzheimer's disease, ascertained from the population-based Swedish twin register. Two reference groups were derived, with 228 and 238 persons, respectively. Occupations were linked to a job-exposure matrix based on magnetic field measurements. Primary occupation, last occupation before reference date, and the occupation with the highest magnetic field exposure during the subject's lifetime were evaluated.

RESULTS

For primary occupation, all relative risk estimates were close to unity. For last occupation, at the exposure level > or = 0.2 microT, a relative risk was found for dementia estimated at 3.3 [95% confidence interval (95% CI) 1.3-8.6] and 3.8 (95% CI 1.4-10.2) for reference groups 1 and 2, respectively. The relative risk for Alzheimer's disease was estimated at 2.4 (95% CI 0.8-6.9) and 2.7 (95% CI 0.9-7.8), respectively. For the occupation with the highest magnetic field exposure, the relative risk estimates were close to unity for reference group 1 and slightly elevated for reference group 2. The relative risk estimates were greater for the subjects who were younger at onset (< or =75 years).

CONCLUSIONS

These results only partially support previous findings, but they indicate that occupational magnetic field exposure may possibly influence the development of dementia.

Childhood adoption: long-term effects in adulthood

Clinicians and researchers have characterized early life experiences as permanent and stable influences on the personality and subsequent life experiences of an individual. Recent conceptualizations have suggested that personal and environmental factors influencing development are not deterministic. Multiple pathways into adulthood are possible. Adoption is one potential early life stressor that may illustrate the usefulness of such conceptualizations for assessing long-term effects in adulthood. Previous studies of adoption have characterized the effects of adoption into adolescence and young adulthood. The purpose of this study was to provide an initial assessment of the long-term impact of adoption. The participants were taken from the Swedish Adoption/Twin Study of Aging. From the original sample, we identified a subsample of 60 pairs of twins who were separated and reared apart, with one member being raised by a biological parent or parents and the other by an adoptive parent or parents with no biological relationship. A series of univariate and multivariate analyses were undertaken to assess the elements associated with being reared in either an adoptive home or the home of biological parent(s). The results suggest few significant effects of adoption on the adult adjustment of adoptees. In particular, the results reflect the important mediating role of childhood socioeconomic status, suggesting that the stress of adoption itself is mediated by the type of rearing environment provided by the adoption process.