Research on twins sheds light on how lifestyle and environment affect health – WSU Insider

Many people’s best ideas may come in the shower, but for Dedra Buchwald, director of the WSU’s Institute for Research and Education to Promote Community Health, a research genius hit her at the local driver’s license office nearly 25 years ago. At the time, a professor of medicine at the University of Washington, Buchwald had gone to replace a lost driver’s license. While filling out a form, a question caught her attention: “Are you twin or full-back?”

At the time, Washington driver’s license numbers were generated based on a combination of characters representing an applicant’s name and date of birth. This meant that twins with similar names could end up with identical numbers, so asking the question allowed the Licensing Department to avoid duplicating the numbers. For Buchwald, it represented an opportunity to work with the state to create an invaluable resource that didn’t yet exist here: a twin research registry.

Now led by Glen Duncan, a professor at Elson S. Floyd College of Medicine and chair of the Department of Nutrition and Exercise Physiology, the Washington State Twin Registry includes thousands of pairs of twins. Based on the twins’ responses to an initial enrollment survey and regular follow-up surveys, Duncan and his team use the registry data to study the connection between people’s living behaviors and their living environment and their physical and mental health.

Studying these complex questions in twins allows researchers to draw conclusions with a greater degree of certainty than they could if they were studying unrelated individuals.

“In every study, when you look at associations between behaviors and outcomes, you don’t know if what you’re seeing is just a correlation or if there’s actually a causal link between the two,” Duncan said. “By doing our research on twins – who share 100% of the genes for identical twins and 50% of the genes for fraternal twins – we can check their shared genetics and the fact that they were raised in a common environment. This allows us to increase our confidence that the associations we are seeing are real and not just statistical artifacts. ”

During the COVID pandemic, the twin registry allowed them to conduct timely research on the effects of pandemic measures on physical and mental health. This included studies on how changes in physical activity levels during stay-at-home orders affected stress and anxiety, the impact of blockages on alcohol consumption, and the effects of mental health on sleep.

In a more recent study of over 6,000 pairs of twins, Duncan and his team analyzed the relationships between five key lifestyle behaviors and body mass index (BMI) and symptoms of depression. Behaviors included in the study were sleeping 8 or more hours per night, consuming 5 or more servings of fruit and vegetables per day, spending a maximum of 2 hours sitting per day, engaging in at least 150 minutes of physical activity per week, and no smoking.

“Since it is very difficult for anyone to meet all five of these standards, what we really wanted to understand is which of these behaviors, alone or in combination, has the greatest impact on these common health outcomes,” Duncan said. “What we found was that meeting standards for moderate to vigorous physical activity and levels of time spent sitting seemed to be the most important for BMI and spending little time sitting and not smoking seemed to have the most potent influence. on symptoms of depression “.

Based on single-point data, their findings suggest the need for researchers to conduct longitudinal studies in a more diverse population of twins to establish a potential causal relationship between these behaviors and outcomes. This could help those struggling to meet multiple health standards know which behaviors to prioritize to increase their chances of successfully battling obesity and depression.

Pending funding, the next major project Duncan’s team hopes to tackle will examine how people’s living environment affects the rate of aging.

“There is a lot of evidence to suggest that people age differently and that the age of your calendar may not mean as much as we thought,” he said. “Our plan is to analyze existing DNA samples collected more than a decade ago along with freshly collected samples from the same twin pairs, determining their biological rather than chronological aging trajectories and associating them with measures of their cognitive function. Ultimately, what we hope to find out is which factors, such as whether or not you live in a disadvantaged area, actually accelerate your biological age regardless of individual risk factors. “

For more information on the Washington State Twin Registry, visit

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