Acknowledgments

This work was supported by National Institute on Aging grants R01 AG018386, AG022381, and AG022982 (to William S. Kremen), and R01 AG018384 (to Michael J. Lyons). It was also, in part, the result of work supported with resources of the VA San Diego Center of Excellence for Stress and Mental Health. The Cooperative Studies Program of the Office of Research & Development of the United States Department of Veterans Affairs has provided financial support for the development and maintenance of the Vietnam Era Twin (VET) Registry. All statements, opinions, or views are solely of the authors and do not necessarily reflect the position or policy of the Department of Veterans Affairs or the United States government, the NIA, or the NIH. Most importantly, the authors gratefully acknowledge the continued cooperation and participation of the members of the VET Registry and their families. Without their contribution this research would not have been possible. We also appreciate the time and energy of many staff and students on the VETSA projects.