Impact of Lifestyle on Cardiovascular and Metabolic Risk Factors in Trauma Exposed Post-9/11 Veterans

Cardiometabolic disease (e.g., type 2 diabetes or cardiovascular disease) is a leading cause of disability and mortality in the United States, and especially so among Veterans. Posttraumatic stress disorder (PTSD) - a salient health concern for many Veterans and their families - is linked to an increased risk of cardiometabolic disease and premature mortality. The precise mechanisms of this relationship are not fully understood. However, recent research suggests that a diagnosis of PTSD increases the risk for hypertension, dyslipidemia and obesity, all of which are known predictors of cardiometabolic disease. A better understanding of what modifiable factors (e.g., lifestyle) influence the link between PTSD and cardiometabolic health and functioning will aid in the development of novel rehabilitative nonpharmacological interventions (e.g., exercise) for cardiometabolic disease and disability in Veterans with PTSD. Physical activity and diet are promising examples of modifiable lifestyle factors. For instance, regular physical activity and a healthy diet strongly reduce the risk for cardiometabolic disease through numerous pathways, such as reductions in blood pressure, blood lipids, adiposity, and by promoting blood glucose control. Simply put, 80% of all new cases of type 2 diabetes are attributed to physical inactivity and poor diet. Low cardiorespiratory fitness is also a critical factor in the risk for disability and mortality due to cardiovascular disease. Despite the clear value and potential impact, there is little research examining relationships between physical activity and diet, cardiometabolic health, and functioning in Veterans with PTSD. This is a critical research gap. Physical inactivity and poor diet increase the risk of cardiometabolic disease and PTSD likely compounds this risk. Veterans with PTSD often lead sedentary lives and make unhealthy dietary choices placing them in a perfect storm for developing cardiometabolic disease and related disability. The purpose of this project is to examine the influence of several modifiable yet understudied lifestyle factors (i.e., physical activity and diet quality) on indicators of cardiometabolic health, and functioning in post-9/11 Veterans. The aims of this project are:

Aim 1 will examine physical activity participation as a potential mechanism linking PTSD to cardiometabolic health and functioning in post-9/11 Veterans from the TRACTS longitudinal cohort study. This study uses self-report physical activity data that is part of the standard TRACTS assessment battery (see below for details). Measurement of self-report physical activity was added to the TRACTS assessments in October of 2018. At this time, physical activity data has been collected from a total of 55 participants at their first Follow-up. Based on past recruitment and current retention rates, there will be about 250 cases with complete physical activity data by the end of the third year of this project.

Aim 2 examines diet quality as a potential mechanism linking PTSD to cardiometabolic health and functioning in post-9/11 Veterans from that TRACTS longitudinal cohort study. Similar to Aim 1, data that is being collected by TRACTS to accomplish this aim. A self-administered web-based 24-hour dietary recall will be used to capture dietary intake and assess diet quality (see below for details). There will be approximately 200 cases with complete dietary intake data by the end of year 4 of the study.

Supplemental Aim, consecutively enrolled TRACTS participants will be invited to participate in this pilot study separately from their standard TRACTS visits. This pilot study will consist of two onsite visits at VABHS, approximately 1-2 weeks apart. In Visit 1, participants will complete a physical activity questionnaire, several mental and physical health assessments, and receive training on how to properly wear an accelerometer. Participants will then be instructed to wear an accelerometer for at least 7 days before returning to VABHS for Visit 2, approximately 9-14 days later. In Visit 2, participants will return the accelerometers, complete a physical activity questionnaire, and a cardiorespiratory fitness test. The goal is to recruit at least 25 participants a year for this study and aim to obtain 100 participants with complete data by the end of year 4 of the study.

Aims 1 and 2 Data Analytic Plan. This aims will use regression-based methods for mediation analysis to explore whether physical activity and/or diet quality mediates the relationship between PTSD and cardiometabolic health and functioning in post-9/11 Veterans. Given the modest sample size, the investigators will use bootstrapped standard errors to reduce potential bias. The investigators will conduct these analyses using the SAS statistical platform. Importantly, the procedures for conducting the proposed analyses using SAS has been previously established. Below, the investigators propose a hypothesized model to test (i.e., physical activity/diet quality as a mediator). However, there are many plausible alternative models (e.g., physical activity/diet quality as a moderator), as well as numerous potential confounders (e.g., age, gender, past or current mental illness, combat exposure, and TBI history). As such, in addition to this proposed model the investigators will evaluate potential alternative models in exploratory analyses.