Current Members

Current D2d Study Members

Anastassios Pittas, MD MS | Principal Investigator

Dr. Pittas is a Professor of Medicine at Tufts University School of Medicine, an Adjunct Professor of Nutrition and Policy at Tufts University Friedman School of Nutrition, Science and Policy and a Center Scientist at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University. Dr. Pittas received his B.S. degree from Massachusetts Institute of Technology and his M.D. degree from Cornell University Medical College.  After completing his Internal Medicine Residency at the New-York Presbyterian Hospital in New York City, NY and his Fellowship in Endocrinology at Tufts Medical Center, Boston, MA, he joined the staff in the Division of Endocrinology, Diabetes and Metabolism at Tufts Medical Center where he has been active in clinical care, research and teaching as they relate to the prevention and treatment of diabetes mellitus. Dr. Pittas serves as the Co-Director of the Dr. Gerald J. and Dorothy R. Friedman New York Foundation for Medical Research Diabetes Self-Education Program and as the Associate Director of the Endocrinology Fellowship Program at Tufts Medical Center.  Dr. Pittas earned his M.S. degree in Clinical Research from Sackler School of Biomedical Sciences at Tufts University in 2006. He is Diplomat of the American Board in Endocrinology and Metabolism.  Dr. Pittas’ was the recipient of a National Institutes of Health K23 Career Development Award. His work on the role of vitamin D and calcium in cardiometabolic disease has been supported by the R01, R21, U34 and U01 mechanisms of the National Institutes of Health (NIDDK and ODS) and the American Diabetes Association.  He has co-authored over 80 publications including peer-reviewed journals, books, book chapters and evidence-based reports. In 2017, he was honored to receive a Biomedical Research Exemplar Award, given to principal investigators who conduct high quality, high-impact research and exemplify professionalism and integrity. In 2017, 2018 and 2019, he was named as one of Top Docs by Boston Magazine. Need more? Visit

Bess Dawson-Hughes, MD
| Co-Investigator

Dr. Dawson-Hughes, M.D. graduated from Tufts University School of Medicine and completed her internship at St. Elizabeth’s Hospital in Brighton, MA. She became Chief Resident in Medicine at St. Elizabeth’s Hospital and went on to an endocrine fellowship at Harvard Medical School and the Brigham and Women’s Hospital. She subsequently received an Individual National Research Service Award at Harvard Medical School. Dr. Dawson-Hughes has served on the councils of several professional organizations, including the American Society for Bone and Mineral Research, the American Society of Clinical Nutrition and the International Bone and Mineral Society. Dr. Dawson-Hughes served as Principal Investigator of the NIH Osteoporosis and Related Bone Diseases Resource Center in Washington, DC from 1998-2003, served on the Advisory Council of the National Institute of Arthritis, Musculo-skeletal, and Skin Diseases from 2000-2004, and served as President of the National Osteoporosis Foundation from 2002-2005. She also served as an Associate Editor of the Journal of Bone and Mineral Research from 1994 through 2002. Dr. Dawson-Hughes has published over 350 peer-reviewed journal articles, book chapters, abstracts, and reviews. Her current research is directed at examining ways in which calcium, vitamin D influence risk of osteoporotic fractures and progression of other chronic diseases. Dr. Dawson-Hughes is frequently invited to speak to scientific and clinical groups both nationally and internationally about her research and on current advances in the diagnosis and treatment of bone diseases.

Ellen Vickery, MS
| Research Associate

Ellen Vickery received her B.A. in Environmental Studies from New York University and her M.S. in Nutritional Epidemiology from the Tufts University Friedman School of Nutrition Science and Policy. Prior to joining the team in the Division of Endocrinology, Ms. Vickery served for six years as a member of the Coordinating Center staff for the multi-center NHLBI-funded IMMEDIATE Trial, first as a research assistant and then as a research coordinator. The study examined the efficacy of an intravenous solution of glucose, insulin and potassium for improving outcomes in patients experiencing acute coronary syndromes and was completed in 2012.

Danielle Riggs
 | Director of Research Administration

Danielle Riggs received her B.S. in Biology from Stonehill College, and has worked within Research Administration at Tufts Medical Center since 2000, most recently joining the leadership team for the Department of Medicine in 2008 as the Director of Administration and Finance.  She oversees the pre- and post-award administration for all federal, foundation, and industry grants and clinical trials throughout the Divisions of Medicine.  In this role, she helped to build the budget management model for D2d, and continues to work with D2d to develop and oversee internal systems for monitoring D2d’s complex budget across sites.

Jason Nelson, MPH
| Study Analyst

Mr. Nelson is a statistician in the Biostatistics Research Center in the Institute for Clinical Research and Health Policy Studies (ICRHPS). Since 2007, through the Biostatistics Research Center, Mr. Nelson has provided statistical research support and data management to clinical researchers throughout the Tufts Medical Center community as well as to collaborators at other institutions. His primary research interest includes spatial analysis of geographic information.  Mr. Nelson received his MPH in biostatistics and epidemiology from Tufts University School of Medicine.

Laila Stevens | Research Coordinator

Laila Stevens received her B.A. in Studio Arts with a double minor in Chemistry and Asian Studies from Bates College in 2021. After graduating, Laila worked in the Hu Lab at the Tufts University School of Medicine. There, the clinical and laboratory focuses were on Lyme disease, both on the bacteria itself as well as organisms’ biological responses. Laila was part of two industry-funded studies relating to the treatment and prevention of Lyme disease as a research technician and study coordinator.