Among Inpatients, Posttraumatic Stress Disorder ...

Copyedited by: Anna Grace R. de Castro

ORIGINAL ARTICLE

Among Inpatients, Posttraumatic Stress Disorder Symptom Severity Is Negatively Associated With Time Spent Walking

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Simon Rosenbaum, PhD,*†‡ Davy Vancampfort, PhD,§k Anne Tiedemann, PhD,‡ Brendon Stubbs, MSc,¶ Zachary Steel, PhD,†#** Philip B. Ward, BMedSc, PhD,*†† David Berle, PhD,*k and Catherine Sherrington, PhD‡ Abstract: This study aimed to determine whether posttraumatic stress disorder (PTSD) symptom severity and psychological and functional variables were associated with physical activity (PA) upon admission to an inpatient facility. PTSD symptoms, depression, anxiety and stress, sleep quality, and PA participation were assessed among 76 participants (age, 47.6 ± 11.9 years; 83% male). Backward stepwise regression analyses identified variables independently associated with time spent walking and engaging in moderate-vigorous PA (MVPA). No significant correlations were found between any of the variables and MVPA. Total PTSD symptoms (r = −0.39, p < 0.001), combined symptoms of depression, anxiety, and stress (r = −0.31, p < 0.01), and sleep behavior (r = −0.24, p < 0.05) were significantly and negatively associated with total walking time. Total PTSD symptoms were the only significant predictor of walking time (B = −0.03, SE = 0.008, β = −0.4; t = −3.4; p < 0.001). Results indicate that increased PTSD symptoms are associated with lower levels of walking. Results highlight the imAQ2 portance of considering symptoms when designing PA programs for people with PTSD. Key Words: PTSD, walking, physical activity, depression (J Nerv Ment Dis 2015;00: 00–00)

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osttraumatic stress disorder (PTSD) occurs after exposure to potentially traumatic events, with an estimated lifetime prevalence of 6.8% (Kessler et al., 2005). PTSD is particularly prevalent and of increasing concern among certain populations, including first responders (police officers, paramedics, firefighters) and veterans. For example, the estimated point-prevalence of PTSD among combat veterans has reported to be in excess of 30% (Richardson et al., 2010). PTSD also significantly increases overall health care consumption, resulting in a growing economic burden (Marshall et al., 2014). PTSD is associated with increased rates of obesity, diabetes, and metabolic syndrome (Boscarino, 2004; Roberts et al., 2015). These cardiovascular disease-related risk factors are at comparable levels with those in people with schizophrenia and bipolar disorder (Vancampfort et al., 2013b) and are considered to contribute to premature mortality (Ahmadi et al., 2011). Several hypotheses, including hypothalamic-pituitary-adrenal and sympathetic-adrenal-medullary dysfunction and inflammation, in addition to lifestyle factors, have

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*School of Psychiatry, University of New South Wales; †South Eastern Sydney Local Health District, Bondi Early Psychosis Programme, Sydney, NSW; ‡Musculoskeletal Division, The George Institute for Global Health and Sydney Medical School, The University of Sydney, Sydney, Australia; §UPC KU Leuven, campus Kortenberg, Department of Neurosciences, KU Leuven–University of Leuven, Kortenberg; kDepartment of Rehabilitation Sciences, KU Leuven–University of Leuven, Leuven, Belgium; ¶School of Health and Social Care, University of Greenwich, London, UK; #St John of God Health Care Richmond Hospital, North Richmond; **Black Dog Institute, NSW; and ††Schizophrenia Research Unit, South Western Sydney Local Health District, Sydney, Australia. Send reprint requests to Simon Rosenbaum, PhD, School of Psychiatry, Black Dog Institute, University of New South Wales, Hospital Rd, Randwick, Sydney, NSW 2301, Australia. E-mail: [email protected]. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved. ISSN: 0022-3018/15/0000–0000 DOI: 10.1097/NMD.0000000000000415

been suggested as potential mechanisms explaining premature mortality (Boscarino, 2004; Dedert et al., 2010; Eraly et al., 2014). For example, people with PTSD are at an increased risk of engaging in binge eating (Hoerster et al., 2015), are significantly more likely to smoke (Fu et al., 2007), have poor sleep behaviors (Lamarche and De Koninck, 2007; Talbot et al., 2013), and are known to be less physically active (de Assis et al., 2008), despite physical activity being the cornerstone of cardiovascular disease prevention and treatment in the general population (Kodama et al., 2009). Recently, Babson et al. (2015) reported that among US veterans receiving residential treatment for PTSD, exercise participation was associated with a greater reduction in PTSD hyperarousal symptom severity at discharge among veterans with poor sleep quality at admission. This study provided preliminary evidence regarding the interactive relationship between exercise participation, sleep quality, and PTSD symptom severity and the potential role of exercise in improving outcomes in this population. Given these preliminary findings, coupled with the increased prevalence of physical comorbidities and compromised cardiovascular health associated with PTSD, there is a growing recognition of the need for novel treatment strategies with the potential to address both physical and mental health outcomes (Farr et al., 2014), including those that target increasing levels of physical activity. Physical activity is defined as any bodily movement produced by skeletal muscle resulting in increased energy expenditure, whereas exercise is a subset of physical activity that is planned, structured, and premeditated (Caspersen et al., 1985). Physical activity and exercise have repeatedly been shown to be effective in improving physical and mental health outcomes in a variety of mental disorders, including depression, schizophrenia, and anxiety (Jayakody et al., 2013; Rosenbaum et al., 2014b; Vancampfort et al., 2014). More recently, a limited yet growing body of literature has reported on the benefits of structured exercise for PTSD (Fetzner and Asmundson, 2014; Mitchell et al., 2014; Rosenbaum et al., 2014a; van der Kolk et al., 2014). For example, a 2-week randomized controlled trial (RCT) of an aerobic exercise (stationary cycling) intervention led to clinically significant reductions in PTSD symptoms (Fetzner and Asmundson, 2014). The authors of the current study reported that a structured, 12-week intervention that combined aerobic and resistance-based exercise for inpatients with severe PTSD led to clinically significant reductions in PTSD symptoms and depression, with simultaneous improvements in physical health parameters including waist circumference and self-reported physical activity (an established predictor of cardiovascular and metabolic disease) (Rosenbaum et al., 2014a). Two additional RCTs have also reported the mental health benefits of yoga as an intervention for patients with PTSD (Mitchell et al., 2014; van der Kolk et al., 2014). Walking has been identified as a safe and accessible form of physical activity for people with PTSD. For example, in a nonrandomized study, Diaz and Motta (2008) reported on the positive impact of a moderate-intensity walking program on female adolescents with PTSD, whereas walking was a key component of the Rosenbaum et al. (2015) intervention. Walking as a physical activity modality has well-established health benefits, including reducing cardiometabolic risk and improved mental health outcomes (Hanson and Jones, 2015)

The Journal of Nervous and Mental Disease • Volume 00, Number 00, Month 2015

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and is likely to have an important role in enhancing total physical activity levels in this population. Therefore, further research into the relationship between time spent walking and PTSD symptom severity is justified. To enhance physical activity participation in people with PTSD, it is important to understand the factors associated with physical activity participation. A growing body of literature demonstrates an inverse relationship between physical activity participation and depression (Mammen and Faulkner, 2013), but the relationship between physical activity and PTSD symptoms is yet to be investigated. Better understanding of the association between PTSD symptom severity, other psychological and functional variables, and participation in walking and other physical activity is urgently needed and is likely to have important implications for physical activity promotion in this population. The aim of this study was therefore to determine whether PTSD symptom severity and other associated psychological and functional variables were associated with time spent in moderate-vigorous intensity physical activity and walking upon admission to a PTSD inpatient facility.

METHODS We analyzed data from participants in a randomized controlled trial reported elsewhere (Rosenbaum et al., 2014a). The study took place at St John of God Hospital Richmond, Australia. The eligibility criteria were a) inpatients, with a Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, diagnosis of PTSD and b) aged 18 to 65 years. Participants were excluded if they were pregnant or planning pregnancy, or if they were medically unfit to participate in an exercise program based on the American College of Sports Medicine (2009) contraindications to exercise. Recruitment was conducted over a 20-month period from 2010 to 2012. The study was approved by the St John of God Health Care Ethics Committee (REF:412). All participants provided written informed consent and self-completed the Posttraumatic Stress Disorder Checklist–Civilian version (PCL-C; Weathers et al., 1993), the Depression, Anxiety and Stress Scale (Lovibond and Lovibond, 1995), the Pittsburgh Sleep Quality Index Addendum for PTSD (Germain et al., 2005), and the International Physical Activity Questionnaire–Short Form (Craig et al., 2003). All objective measures (e.g., anthropometric assessments) were conducted by allied health and nursing staff blinded to group allocation. A priori sample size calculation determined that 80 participants were required to detect as significant a 5-point between-group difference on the PCL-C.

Outcome Measures The PCL-C The PCL-C is a commonly used 17-item self report questionnaire assessing the key symptoms of PTSD (Weathers et al., 1993). Scores range from 17 to 85, with higher scores indicating higher symptom severity. A score of 45 is consistent with a diagnosis of primary PTSD (Weathers et al., 1993).

The Depression, Anxiety, and Stress Scale The 42-item Depression, Anxiety, and Stress Scale (DASS) is a self-report questionnaire that measures the related negative emotional states of depression, anxiety, and tension/stress (Lovibond and Lovibond, 1995). Scores range from 0 to 126, with higher scores reflecting greater symptom severity. Separate scores can be calculated for each of the three domains of depression, anxiety, and stress in addition to a global total score (Lovibond and Lovibond, 1995). The psychometric properties of the DASS have been comprehensively evaluated, and it has been found to be valid, reliable, and responsive to treatment (Lovibond and Lovibond, 1995). 2

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Pittsburgh Sleep Quality Index–Addendum for PTSD The Pittsburgh Sleep Quality Index–Addendum for PTSD (PSQIA) is a 10-item self-report questionnaire that assesses sleep quality in PTSD (Germain et al., 2005). Scores range from 0 to 21, with a score of 4 previously shown to discriminate adults with PTSD (Germain et al., 2005).

The International Physical Activity Questionnaire–Short Form The International Physical Activity Questionnaire–Short Form (IPAQ-SF) is a self-report physical activity questionnaire that was used to assess the level of physical activity participation. The IPAQ-SF assesses activity in the previous 7-day period and includes four questions that assess participation in vigorous and moderate-intensity exercise, in addition to the total time spent walking, and the total time spent sitting (Craig et al., 2003). The IPAQ-SF has previously been used and validated among patients with PTSD. When compared with an objective measure of physical activity, correlations of a magnitude comparable with those typically observed in similar correlation studies (range r = 0.2–0.4) in the general population were found (Rosenbaum et al., 2014c).

Waist Circumference Waist circumference was measured to the nearest 0.5 cm at the midway point between the iliac crest and the costal margin. Waist circumference, as opposed to body weight or body mass index (BMI), was measured owing to the established association with obesityrelated health risk (Janssen et al., 2004).

Statistical Analyses The distributions of variables were assessed using the ShapiroWilks test. IPAQ data were transformed using a logarithmic transformation (log base 10 plus 1) because of some participants reporting zero episodes of at least 10-minute bouts of walking as per the IPAQ-SF instructions. Pearson correlation coefficients were used to assess correlations between variables. Backward stepwise regression analyses were performed to identify variables that were independently associated with time spent walking and physical activity participation. Significant ( p < 0.05) variables in the correlation analyses were entered into the final multivariable model. To test for multicollinearity, a variance inflation factor (VIF) was computed for each independent variable in the model. Values above 3 were used to indicate a multicollinearity problem in the model (Kleinbaum et al., 2013). To avoid multicollinearity, we adopted a conservative VIF threshold of less than 3, and if violated, only the strongest correlation coefficient was inserted into the model (Field, 2000). Statistical analyses were performed using the statistical package SPSS version 22.0 (SPSS Inc, Chicago, IL).

RESULTS Participants Participant characteristics can be seen in Table 1. The mean (SD) age was 47.6 (11.9) years (83% male), with 78% of the sample reporting trauma that was experienced in the course of their occupation. PTSD symptoms were high, consistent with the population being recruited from an inpatient facility. The mean walking time was 286.7 ± 330.9 minutes per week; moderate physical activity, 135.1 ± 254.9 minutes per week; and vigorous physical activity, 133.2 ± 253.5 minutes per week. In total, 91% of participants were overweight or obese, with 37% meeting criteria for obesity class I (BMI 30–34.9 kg/m2), 9% meeting obesity class II (BMI 35–39.9 kg/m2), and 5% of the sample meeting criteria for obesity class III (BMI >40 kg/m2). © 2015 Wolters Kluwer Health, Inc. All rights reserved.


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TABLE 1. Baseline Characteristics (n = 76) Male, n (%) Age (yrs) Total PCL-C DASS BMI (kg/m2), n (%) Healthy (18.5–24.9) Overweight (25–29.9) Obese (≥30) IPAQ-SF (min/wk) Vigorous Moderate Walking PSQI (total; 0–21)

TABLE 3. Unstandardized and Standardized Regression Coefficients for Variables With Time Spent Walking as the Dependent Variable 63 (83) 47.6 (11.9) 64.3 (12.0) 73.6 (31.1) 7 (9) 30 (40) 39 (51) 133 (254) 135 (255) 287 (331) 16.9 (6.3)

Data are presented as mean (SD), unless stated otherwise. PSQI indicates Pittsburgh Sleep Quality Index.

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Walking and PTSD Symptoms

No significant correlations were found between total time spent in moderate and vigorous physical activity and any of the clinical variables. In contrast, time spent walking was significantly and negatively associated with PTSD symptoms as assessed by the total PCL-C score (r = −0.39, p < 0.001; large effect size, Cohen's d = 0.8). A significant and negative association was also found between time spent walking and symptoms of depression, anxiety, and stress as assessed by the DASS (r = −0.31, p < 0.01; medium effect size, Cohen's d = 0.6), as well as sleep behavior as assessed by the PSQIA (r = −0.24, p < 0.05; medium effect size, Cohen's d = 0.5). Table 2 shows the correlations between time spent walking and clinical variables. The significant variables (PCL-C total, DASS total, and sleep behavior) were included in the backward stepwise regression analyses. The only significant predictor of walking time was PTSD symptoms (B = −0.03, SE = 0.008, β = −0.4; t = −3.4 p < 0.001). PTSD symptoms explained 13% of the overall variance in walking time (Table 3).

DISCUSSION The current study demonstrates that inpatients with PTSD experiencing more severe symptoms, as reported by the PCL-C, spend less time walking. Even after adjustment for other variables,

Variable Total PCL-C DASS PSQIA

B −0.03 −0.001 −0.002

SE B

β −0.36 −0.02 −0.01

0.01 0.004 0.02

*Full model analysis of variance, df = 3,72, F = 3.9, p = 0.01, r2 = 0.14.

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a significant, negative correlation between time spent walking and symptoms of PTSD remained. The association between PTSD symptoms and time spent walking indicates that interventions designed to increase walking and physical activity participation could be specifically targeted at those patients with higher levels of PTSD symptoms. Preliminary evidence of a reciprocal relationship between depressive symptoms and walking impairment has been recently been reported in other chronic conditions such as multiple sclerosis (Ensari et al., 2015), whereas in people with severe mental illness, walking has been shown to be a safe, popular, and effective modality of physical activity that can be introduced in a familiar setting and potentially leading to more autonomously motivated participation (Soundy et al., 2014a; Vancampfort et al., 2013a). Therefore, future research should investigate the differential impact of walking interventions for people with varying levels of PTSD symptoms. The outcomes of such studies would assist clinicians in the design and delivery of walking interventions. No association was found between symptoms and total moderate-vigorous intensity activity. The lack of a relationship between moderate-vigorous physical activity and symptoms of PTSD, depression, anxiety, and stress was an unexpected finding that requires replication in future studies. One potential explanation for this lack of association is the difficulty in obtaining accurate estimates of selfreported physical activity via questionnaire. Although the IPAQ has previously been used and validated among inpatients with PTSD (Rosenbaum et al., 2014), self-report measures have limitations in comparison with objective measures of physical activity participation (Soundy et al., 2014b). Specific to PTSD, it has been suggested that those from a veteran or emergency services background may tend to report physical activity levels and intensity reflecting pretrauma levels, despite the IPAQ specifically asking about the previous 7-day period (Rosenbaum et al., 2014). Given the cross-sectional nature of the study, we were not able to investigate the mediating relationships between

TABLE 2. Association Between Walking, Moderate, and Vigorous Physical Activity and Clinical Variables (n = 76)

PTSD symptoms Re-experiencing Avoidance Hyperarousal DASS total Depression Anxiety Stress Waist circumference

Mean ± SD

Walking

Moderate Physical Activity

Vigorous Physical Activity

Effect Size (Cohen's d)

64.3 ± 12.0 18.0 ± 4.3 26.6 ± 5.4 19.8 ± 4.0 73.6 ± 31.1 25.6 ± 11.8 20.2 ± 11.0 28.1 ± 11.0 104.3 ± 14.6

−0.39** −0.39** −0.39** −0.24* −0.31* −0.31* −0.30* −0.27* −0.02

0.05 0.08 −0.05 0.13 0.04 −0.1 0.08 0.14 0.15

0.04 0.15 −0.14 0.15 0.09 −0.17 0.22 0.21 −0.23

0.8 0.8 0.8 0.5 0.7 0.7 0.6 0.5 0

Cohen's d: small, 0.0–0.2; medium, 0.3–0.5; large, 0.8–2. *Significant at the p < 0.05 level. **Significant at the p < 0.001 level.

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physical activity and PTSD symptoms. This also limits interpretation regarding the direction of the association. In addition, the data analyzed for this study were from participants recruited to a clinical trial investigating the impact of exercise on PTSD. As such, it should be acknowledged that a potentially biased sample of participants may have been recruited, reflecting those more willing or interested in participating in physical activity.

Clinical Implications Symptom severity should be considered when designing and delivering interventions aiming to increase walking and physical activity participation in people with PTSD. Walking is a low-risk physical activity that is accessible and can be encouraged by nonexercise clinicians. Given the high rates of overweight, obesity, and metabolic syndrome among people with PTSD, the benefits of increased walking are likely to simultaneously improve physical health parameters (Rosenbaum et al., 2015). Barriers to physical activity participation faced by people experiencing mental disorders (including poor motivation and a lack of prioritizing of physical activity by health care professionals) must be addressed using evidence-based strategies (Soundy et al., 2014c). For example ensuring individualized and targeted exercise programming, addressing social support, facilitating goal setting, and ensuring adequate opportunity for participation in exercise while attending inpatient treatment may help promote physical activity participation among this vulnerable population (Bruins et al., 2014).

Future Research Future research should investigate the impact of physical activity interventions on people with varying levels of PTSD symptoms. Future studies should also consider using objective physical activity monitoring devices and examine the potential benefits of increased walking on PTSD treatment outcomes, including engagement with treatment services and civilian reintegration. The effect of increased physical activity on the physical health outcomes of people experiencing PTSD and the link between such outcomes and PTSD symptoms also warrants further study, and the mechanisms giving rise to such associations also need elucidation (Farr et al., 2014). In conclusion, the current study demonstrated that increased levels of PTSD symptoms are associated with lower levels of walking. Given the need to develop novel interventions to improve the physical and mental health of people with PTSD, walking may offer a lowcost, accessible treatment modality. DISCLOSURE Prof. Sherrington is supported by a Fellowship from the Australian National Health and Medical Research Council. Dr Vancampfort is funded by the Research Foundation Flanders (FWO-Vlaanderen). The other authors declare no conflict of interest. REFERENCES Ahmadi N, Hajsadeghi F, Mirshkarlo HB, Budoff M, Yehuda R, Ebrahimi R (2011) Post-traumatic stress disorder, coronary atherosclerosis, and mortality. Am J Cardiol. 108:29–33. American College of Sports Medicine (2009) ACSM's guidelines for exercise testing and prescription (8th ed, Vol 220). Philadelphia, PA: Lippincott Williams & Wilkins. Babson KA, Heinz AJ, Ramirez G, Puckett M, Irons JG, Bonn-Miller MO, Woodward SH (2015) The interactive role of exercise and sleep on veteran recovery from symptoms of PTSD. Ment Health Phys Act. 8:15–20. Boscarino JA (2004) Posttraumatic stress disorder and physical illness: Results from clinical and epidemiologic studies. Ann N Y Acad Sci. 1032:141–153. Bruins J, Jörg F, Bruggeman R, Slooff C, Corpeleijn E, Pijnenborg M (2014) The Effects of lifestyle interventions on (long-term) weight management,

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