Completed Studies

Major depression is a complex disorder with no single, direct causal mechanism. Morbidity has been linked to genetic processes, developmental history, and unique environmental exposures. Epigenetic mechanisms, especially DNA methylation, are also likely important factors in the pathogenesis of major depressive disorder (MDD). A community-based twin sample has many advantages for epigenetic studies, given the […]

Variation in healthy aging and lifespan is ascribed more to various non-genetic factors than to inherited genetic determinants, and a major goal in aging research is to reveal the epigenetic basis of aging. One approach to this goal is to find genomic sites or regions where DNA methylation correlates with biological age. Using health data […]

Objective: DNA methylation has been associated with both early life stress and depression. This study examined the combined association of DNA methylation at multiple CpG probes in five stress-related genes with depressive symptoms and tested whether these genes methylation mediated the association between childhood trauma and depression in two monozygotic (MZ) twin studies. Methods: The current analysis […]

Smart cities use information and communication technologies (ICT) to scale services include utilities and transportation to a growing population. In this article we discuss how smart city ICT can also improve healthcare effectiveness and lower healthcare cost for smart city residents. We survey current literature and introduce original research to offer an overview of how […]

Social capital is associated with depression independently of individual-level risk factors. We used a sample of 1586 same-sex twin pairs to test the association between seven measures of social capital and two related measures of neighborhood characteristics with depressive symptoms accounting for uncontrolled selection factors (i.e., genetics and shared environment). All measures of cognitive social […]

Background: Variants in the first intron of the fat mass and obesity-associated (FTO) gene increase obesity risk. People with “high-risk” FTO genotypes exhibit preference for high-fat foods, reduced satiety responsiveness, and greater food intake consistent with impaired satiety. Objective: We sought central nervous system mechanisms that might underlie impaired satiety perception in people with a higher risk […]

Why do people distrust others in social exchange? To what degree, if at all, is distrust subject to genetic influences, and thus possibly heritable, and to what degree is it nurtured by families and immediate peers who encourage young people to be vigilant and suspicious of others? Answering these questions could provide fundamental clues about the sources of individual differences […]

Objective: We used quantitative genetic methods to evaluate whether sleep quality, pain, and depression symptoms share a common genetic diathesis, to estimate the genetic and environmental sources of covariance among these symptoms, and to test for possible causal relationships. Methods: A community sample of 400 twins from the University of Washington Twin Registry completed standardized self-report questionnaires. […]

Objectives: Hypothalamic-pituitary-adrenal (HPA) axis dysregulation is associated with chronic pain. Studying pain sensitivity and the HPA axis could elucidate the role of stress in chronic pain development, which might be influenced by familial factors, including genes. Methods: Associations between pain sensitivity and salivary cortisol and familial confounding in these associations were examined in 88 female, community-based twin […]

Introduction: Habitual short sleep duration is associated with adverse metabolic, cardiovascular, and inflammatory effects. Co-twin study methodologies account for familial (eg, genetics and shared environmental) confounding, allowing assessment of subtle environmental effects, such as the effect of habitual short sleep duration on gene expression. Therefore, we investigated gene expression in monozygotic twins discordant for actigraphically phenotyped […]

Objective: To test the relationship of anxiety to caloric intake and food cue perception in women and men. Methods: Fifty-five twins (26 complete, 3 incomplete pairs; 51% women) underwent 2 functional magnetic resonance imaging (fMRI) scans (before and after a standardized meal) and then ate at an ad libitum buffet to objectively assess food intake. State and […]

Walking is the most popular choice of aerobic physical activity to improve health among U.S. adults. Physical characteristics of the home neighborhood can facilitate or hinder walking. The purpose of this study was to quantify neighborhood walking, using objective methods and to examine the association between counts of walking bouts in the home neighborhood and […]

Purpose: Urological chronic pelvic pain syndromes have refractory bladder or pelvic pain as the dominant symptom. This has been attributed to changes in the central nervous system caused by a chronic barrage of noxious stimuli. We developed what is to our knowledge a novel challenge protocol that induced bladder distention in study participants to reproduce pain […]

A full understanding of the mechanisms involved in chronic pain could make a significant difference in the quality of life of chronic pain patients, as well as healthcare costs and productivity. Previous clinical studies have found associations between pain conditions and levels of C-Reactive Protein (CRP), a general indicator of inflammation in the body. This […]

This study looked at the relationship between how much sleep a person gets and how it influences metabolism and measures of inflammation, both of which are related to obesity. Fifty five (55) MZ twin pairs were invited to participate in this study. A twin study was done because it is the ideal way to look at […]

Results of a previous pilot study about oral herpes in twins suggested that there are genetic factors in an infected person that strongly influence the reactivation (waking up) of the HSV-1 virus from a dormant (sleeping) state to cause cold sores. The purpose of this study was to understand how the genes of the host, […]

A total of 99 female twin pairs (198 women) participated in this study to understand more about the causes and conditions associated with chronic widespread pain. This study examined perceptions of pain, factors related to sleep, hormones related to the body’s response to stress, and inflammatory markers that might affect sensitivity to pain. A twin […]

Scientists have recently discovered a number of hormones that control appetite and regulate weight. These hormones travel in the bloodstream and some of them change rapidly with every meal. They influence when we get hungry, how full we feel and probably even what foods taste good to us.  The main purpose of this study was […]

Obesity increases the risk of many diseases, including diabetes, heart disease, and cancer. There is evidence that there may be a link between obesity and inflammation (irritation) in the body and the kinds of bacteria found in the gut. The goal of this study was to better understand how body weight in adults and the […]

There are big differences in how people respond to severe bacterial infection.  The inflammatory response of white blood cells to harmful bacteria that invade the body may play an important role in determining how well a patient will be able to fight the infection. The purpose of this study was to better understand how genetic […]