The purpose of The Veteran Health Study (CSP #569) is to better understand the mental and physical health of veterans as they get older. We are inviting approximately 10,000 members of the Vietnam Era Twin (VET) Registry to participate. As veterans approach their mid-sixties, it is important to understand the impact of wartime deployment on health and mental health outcomes nearly 40 years later.

The investigators will assess the prevalence of post-traumatic stress disorder (PTSD) and other mental and physical health conditions for Vietnam era veterans, and explore the relationship between PTSD and other conditions.

CSP #569 involves 3 phases of data collection. In Phase I, VET Registry members are invited to complete a paper and pencil questionnaire including items on physical and mental health, disability, health behaviors, demographic information and use of health care services. After completing Phase I, VET Registry members are invited to Phase II which involves a telephone interview about mental health. In Phase III, some of those who participated in Phase I will be invited to a sub-study confirming self-reported heart disease and diabetes using a provider survey.

Data collected for CSP #569 will be combined with existing VET Registry data. This will provide a rich picture of the health of Vietnam era veterans and the influence of PTSD on the lives of veterans.

Inclusion Criteria:

• All twins who are currently active in the VET Registry will be invited to participate in CSP #569.

Exclusion Criteria:

• Unable or unwilling to provide informed consent

All subjects are members of the Vietnam Era Twin Registry, and are males born between 1939-1957.