The study used an ongoing well-characterized cohort, the VA Normative Aging Study (NAS), to recruit middle-aged and older community-dwelling men and women into the study. Using a variety of validated psychological and psychiatric screening instruments--including the Brief Symptom Inventory, the Composite International Diagnostic Interview, the Spielberger State-Trait Anxiety Inventory, and the Crown-Crisp Index--the study population was characterized in terms of symptoms of anxiety and diagnosis of anxiety disorders. Cardiovascular autonomic control was then assessed among anxious and non-anxious individuals using non-invasive time-domain and power-spectral measures of heart rate and blood pressure variability. Cardiac output, total peripheral resistance, and end-tidal pCO2 were simultaneously assessed.