Somatic health and lifestyle habits in obsessive-compulsive disorder

<p dir="ltr">Background: Obsessive-compulsive disorder (OCD) is a debilitating psychiatric disorder characterized by intrusive thoughts, images, or urges (i.e., obsessions) and recurrent behaviors and rituals aimed at reducing anxiety or a feared consequence (i.e., compulsions). Beyond the significant impairment and psychological burden associated to the disorder, there is growing evidence suggesting that individuals with OCD also have an increased risk of developing somatic conditions, with the most robust evidence focusing on cardiometabolic conditions such as cardiovascular disease, obesity, and type 2 diabetes. Studies suggest that environmental and behavioral factors, such as unhealthy lifestyle habits (e.g., physical inactivity, unhealthy diets, use of alcohol and tobacco), may play a significant role in this association. However, knowledge about the specific lifestyle habits of individuals with OCD remains limited. Assessing lifestyle habits can be challenging, and there is a need to find acceptable and valid methods to measure them. Furthermore, regardless of the underlying mechanisms, promoting healthier habits has shown to be crucial to prevent somatic health problems, but structured programs to support the development of healthier habits in individuals with OCD are lacking.</p><p dir="ltr">Aim: The overall aim of this doctoral thesis was to improve our understanding of the somatic health and lifestyle habits of individuals with OCD, and to develop and evaluate the feasibility of a lifestyle intervention tailored to this population. The thesis comprised four studies. Study 1 aimed at exploring the somatic health and lifestyle habits of adults with self-reported OCD through an online survey. Study 2 aimed at evaluating the feasibility of using ecological momentary assessment (EMA) methods to study lifestyle habits in youth with OCD. Study 3 investigated the familial coaggregation of OCD and cardiometabolic conditions using the Swedish population-based registers. Study 4 aimed at developing and evaluating the feasibility and preliminary effects of a structured lifestyle intervention, named LIFT, for adults with OCD and cardiometabolic risk factors.</p><p dir="ltr">Methods: Study 1 was a cross-sectional study including 496 individuals with self-reported OCD who completed an international online survey. Descriptive statistics were used to analyze the results, and subgroup analyses (by OCD symptom severity, gender, and age group) were performed. Study 2 was a feasibility study of 20 adolescents with OCD that completed a 14-day EMA protocol with questions on lifestyle habits (physical activity, sitting time, food habits, and sleep). Feasibility and acceptability of the method were assessed by exploring recruitment rate, study retention, response compliance, and experiences of participation. Feasibility of the EMA analyses was assessed by using linear mixed-effects methods to compare the lifestyle habits of 17 youth from the OCD group with those of a comparator group of 15 youth recruited from schools. Study 3 was a register-based study using a range of Swedish administrative and health registers to investigate the risk of cardiometabolic conditions (including cardiovascular disease, obesity, type 2 diabetes, and hyperlipidemia) in relatives with different degrees of relatedness (including parents, full and half siblings, aunts/uncles, and cousins) to probands with or without OCD. Over 6,000,000 individuals born between 1950 and 2008 were included, of which 50,212 had a diagnosis of OCD. Cox proportional hazards regression models incorporating time-varying exposures were used to estimate hazard ratios and corresponding 95% confidence intervals. Study 4 was a feasibility trial of a structured lifestyle intervention in 25 individuals with OCD and cardiometabolic risk factors. The intervention consisted of one individual session, six biweekly educational sessions, and 12 exercise sessions delivered over 3 months. Feasibility was assessed by exploring recruitment rate, adherence, credibility, and satisfaction. Mixed-effects linear regression models were used to analyze preliminary effects on lifestyle habits, cardiometabolic risk measures, mental health symptoms, and quality of life.</p><p dir="ltr">Results: In Study 1, over 71% participants reported at least one somatic health condition, 48% were overweight/obese, 55% presented with low levels of physical activity, 37% reported unhealthy diets, 22% reported risky alcohol use, and 54% non-restorative sleep. Many participants expressed motivation to change their habits, yet only half had succeeded. Subgroup analyses showed overall similar results. In Study 2, EMA was found feasible and acceptable to evaluate lifestyle habits in youth with OCD. A total of 65% of the contacted individuals agreed to participate, and we found high levels of retention (90% of included participants completed the study) and compliance (73% of 210 lifestyle items were responded). The OCD group reported, on average, low levels of physical activity, almost daily consumption of vegetables, breakfast, and sweets, 7-9 hours of sleep, and low levels of morning energy. Between-group comparisons were feasible. Study 3 showed that individuals with OCD had an increased risk of cardiovascular disease (HR 1.47, 95% CI 1.43 to 1.51), obesity (HR 1.69, 95% CI 1.63 to 1.74), type 2 diabetes (HR 2.01, 95% CI 1.90 to 2.12), and hyperlipidemia (HR 1.42, 95% CI 1.33 to 1.52). The familial coaggregation analyses showed that relatives of individuals with OCD, compared to the relatives of those without, displayed only small increases in risk, with no clear gradient across different degrees of relatedness. In Study 4, LIFT was found feasible, acceptable, and safe, with low attrition (16%) and high participant satisfaction. Preliminary efficacy results showed statistically significant improvements in dietary habits, alcohol consumption, stress levels, OCD symptom severity, and functional impairment. No significant changes were found in physical activity, sleep, or cardiometabolic markers.</p><p dir="ltr">Conclusions: The results from this thesis add to the limited but growing evidence that individuals with OCD have an increased risk of somatic health conditions and offer preliminary evidence that this association is likely to be related to unique environmental risk factors, such as lifestyle habits, rather than familial factors. A newly-developed, structured lifestyle intervention to promote healthier lifestyle habits in individuals with OCD is feasible, but its efficacy should be explored in a larger randomized controlled trial. The findings of this work highlight the need to acknowledge the somatic health and lifestyle habits of individuals with OCD. Preventive strategies to avoid adverse outcomes are warranted.</p><h3 dir="ltr">List of scientific papers</h3><p dir="ltr">I. <b>Holmberg, A.</b>, Martinsson, L., Lidin, M., Rück, C., Mataix-Cols, D., & Fernández de la Cruz, L. (2024). General somatic health and lifestyle habits in individuals with obsessive- compulsive disorder: an international survey. BMC Psychiatry, 24(1), 98. <br><a href="https://doi.org/10.1186/s12888-024-05566-w">https://doi.org/10.1186/s12888-024-05566-w</a><br><br></p><p dir="ltr">II. Holmberg. A.,*, Thorsson, M.*, Nordin, G., Houghton, E., Mataix-Cols, D., Fernández de la Cruz, L., & Cervin, M. (2026). Using ecological momentary assessment to examine lifestyle habits in young people with obsessive-compulsive disorder: a feasibility study. [*Joint first authors] [Submitted]</p><p dir="ltr">III. <b>Holmberg, A</b> .* , Pol-Fuster, J .* , Kuja-Halkola, R., Larsson, H., Lichtenstein, P., Chang, Z., D'Onofrio, B. M., Brikell, I., Sidorchuk, A., Isomura, K., Crowley, J. J., Martinsson, L., Rück, C., Mataix-Cols, D., & Fernández de la Cruz, L. (2025). Multigenerational family coaggregation study of obsessive-compulsive disorder and cardiometabolic disorders. BMJ Mental Health, 28(1), e301323. [*Joint first authors]<br><a href="https://doi.org/10.1136/bmjment-2024-301323 " rel="noreferrer" target="_blank">https://doi.org/10.1136/bmjment-2024-301323</a> <br><br></p><p dir="ltr">IV. <b>Holmberg, A.</b>, Lidin, M., Lenninger, D., Asplund, S., Lavebratt, C., Rück, C., Martinsson, L., Mataix-Cols, D., & Fernández de la Cruz, L. (2025). A structured lifestyle intervention to reduce cardiometabolic risk factors in individuals with obsessive-compulsive disorder: feasibility trial. BJPsych Open, 2025;11(5):e171. <a href="https://doi.org/10.1192/bjo.2025.10774" rel="noreferrer" target="_blank">https://doi.org/10.1192/bjo.2025.10774</a></p>