Date of Award
Doctor of Philosophy (PhD)
Chair and Committee
Leopoldo J. Cabassa
Shenyang Guo, Darrell Hudson, Phillip Marotta, Michael Park,
People with serious mental illness (SMI; e.g., schizophrenia) die 10–25 years earlier than people in the general population largely due to chronic medical conditions (e.g., cardiovascular disease [CVD]), and having a co-occurring substance use disorder (SUD) increases this risk even further compared to having either disorder alone. This is concerning since 50% of people with SMI will be diagnosed with a co-occurring SUD in their lifetime and 40%-80% are current tobacco smokers. Healthy lifestyle interventions can improve the health of people with SMI by offering a package of services aimed at improving physical activity, dietary habits, and engagement in health promoting activities, but little is known about how substance use and tobacco smoking affect healthy lifestyle intervention mechanisms of change (e.g., diet, physical activity) and outcomes (e.g., weight loss).The proposed study sought to understand how tobacco smoking and substance use among people with SMI impacts healthy lifestyle intervention factors (e.g., improvements in diet and physical activity) and health outcomes (e.g., weight loss). Understanding this impact is an important step in the development of personalized interventions directed at reducing CVD risk factors, the leading cause of early mortality among people with co-occurring disorders. Further, despite a national push to integrate behavior and physical healthcare, there is limited research into the multimorbidity of substance use disorders and chronic diseases among people with SMI. Advancing knowledge in this area will provide information important to the integration of behavioral and physical healthcare.This dissertation study uses data from a recently completed National Institute of Mental Health (NIMH) funded trial testing the effectiveness of a peer-led healthy lifestyle intervention for 314 participants with SMI and overweight/obesity (BMI ≥25) living in supportive housing. The intervention helped participants achieve clinically significant weight loss (≥5%) through changes in dietary practices and physical activity. The present study addresses the following aims: 1) examine the baseline sociodemographic (e.g., education), mental health (e.g., SMI diagnosis), physical health (e.g., physical health conditions), and healthy lifestyle factor (e.g., diet) correlates of substance use and tobacco smoking, 2) examine how the impact of receiving either the peer-led healthy lifestyle intervention or usual care on weight loss throughout the trial was moderated by participants’ baseline tobacco smoking or substance use status, and 3) explore how tobacco smoking and substance use at baseline moderate the mediating effects that improvements in diet and physical activity over the course of the trial have on weight loss at 18-months.Most participants were from racial/ethnic minoritized groups (82%) and 42% were female. The mean age of participants was 49. Approximately 57% were diagnosed with schizophrenia or a schizoaffective condition, 50% anxiety related conditions, 47% bipolar, and 63% were taking an antipsychotic medication. At baseline, 17% had cardiovascular disease, 32% diabetes, 31% arthritis, and on average, participants had 3.7 different chronic medical conditions. The average BMI of participants was 33. At baseline, 63% (N=197) of participants were current tobacco smokers and 25% (N=79) were using substances (i.e., alcohol or drugs).The aim 1 results indicated that the odds of being a current smoker was significantly higher for females, people with fewer years of education, and those with lower BMI’s. Poor – fair self-rated health (compared to good – excellent) was consistently related to any substance use, more days of substance use, and more problematic substance use. Additionally, a higher number of medical conditions was related to more days of substance use and more problematic substance use. Fewer sitting minutes per day was significantly associated with any substance use and more days of substance use at baseline. Any substance use and more days of substance use were related to younger age and more years of education. Also, females were less likely to have problematic substance use than those who identified as male. Additionally, racial and ethnic minoritized participants had a higher risk of more substance use days and having bipolar disorder was significantly associated with more days of substance use.Aim 2 results found that the main effects of baseline weight and tobacco smoking were important predictors of weight loss over the course of the trial, but these did not moderate the effect of the intervention. Additionally, the main effect of total days of substance use was a predictor of weight loss over the course of the trial but did not moderate the effect of the intervention. Aim 3 results found that neither baseline tobacco smoking nor substance use influenced weight loss indirectly through diet or physicalactivity.An important finding of this study was that more days of substance use and more problematic substance use were significantly associated with worse self-rated health and a higher number of medical conditions. In addition, this study challenges researchers to take substance use and tobacco smoking into account when testing healthy lifestyle interventions since smoking and total days of substance use at baseline were significantly associated with more weight loss over the course of the trial. The potential impact of substance use on diet, physical activity, and weight loss and the known association of smoking cessation and weight gain, have important implications for the personalization of healthy lifestyle interventions.In conclusion, the proposed study sought to understand how tobacco smoking and substance use among people with SMI impacted their physical health at baseline and how it impacted their diet, physical activity, and weight loss during a healthy lifestyle intervention. Even though there is a national push to integrate behavioral and physical healthcare, there is limited research into the multimorbidity of substance use disorders and chronic diseases among people with SMI. This study advances knowledge in this area and provides information important to the integration of behavioral and physical healthcare. This study also provides information critical for the development of personalized interventions directed at reducing CVD risk factors, the leading cause of early death among people with SMI and co-occurring disorders. Health interventions can no longer be siloed into weight loss, diet, PA, tobacco smoking, substance use, coordinated care, etc. It is becoming increasingly clear that there is an integral connection between all aspect of physical and mental health and intervening in one area while ignoring another will make it difficult to move the needle and improve quality of life and life expectancy for people with SMI.
Hawes, Mark R., "The Physical Health of People with Co-occurring Serious Mental Illness and Substance Use Disorders" (2023). Brown School Theses and Dissertations. 13.