The structure of DSM-5 posttraumatic stress disorder symptoms in war veterans

Background and Objectives: The present research examined the underlying factor structure of posttraumatic stress disorder (PTSD) as conceptualized in the recently published fifth edition of the Diagnostic and statistical manual of mental disorders (DSM-5). Design: Participants were 258 trauma-exposed Iraq/Afghanistan war veterans. Methods: A self-report measure of PTSD symptoms was administered to all participants and confirmatory factor analysis (CFA) was used to compare several different models of PTSD. Results: CFA revealed that the best-fitting model was a six-factor model in which symptoms loaded onto the factors of intrusion, avoidance, negative affect, anhedonia, dysphoric arousal, and anxious arousal. Conclusions: These findings have important implications for ongoing conceptualization of PTSD and suggest that additional modifications to the diagnostic criteria for PTSD may still be warranted to more accurately reflect the underlying structure of PTSD symptoms.     

A meta-analytic investigation of the structure of posttraumatic stress disorder symptoms

Converging lines of evidence have called into question the validity of conceptualizations of posttraumatic stress disorder (PTSD) based on the Diagnostic and Statistical Manual of Mental Disorders (DSM; American Psychiatric Association, 2000) and suggested alternative structural models of PTSD symptomatology. We conducted a meta-analysis of 40 PTSD studies (N = 14,827 participants across studies) that used a DSM-based measure to assess PTSD severity. We aggregated correlation matrices across studies and then applied confirmatory factor analysis to the aggregated matrices to test the fit of competing models of PTSD symptomatology that have gained support in the literature. Results indicated that both prominent 4-factor models of PTSD symptomatology yielded good model fit across subsamples of studies; however, the model comprising Intrusions, Avoidance, Hyperarousal, and Dysphoria factors appeared to fit better across studies. Results also indicated that the best fitting models were not moderated by measure or sample type. Results are discussed in the context of structural models of PTSD and implications for the diagnostic nosology.     

Posttraumatic Stress Disorder Symptom Clusters and Acquired Capability for Suicide: A Reexamination Using DSM-5 Criteria

This study used the interpersonal–psychological theory of suicide to explore the relationships among DSM-5 posttraumatic stress disorder (PTSD) symptom clusters derived from the six-factor anhedonia model and facets of acquired capability for suicide (ACS). In a sample of 373 trauma-exposed undergraduates, most PTSD symptom clusters were negatively associated with facets of ACS in bivariate correlations, but the anhedonia cluster was positively associated with ACS in regression models. Structure coefficients and commonality analysis indicated that anhedonia served as a suppressor variable for the other symptom clusters. Our findings further elucidate the complex relationship between specific PTSD symptom clusters and ACS.     

Symptoms of Post-Traumatic Stress Disorder in Bereaved Children and Adolescents: Factor Structure and Correlates

This study investigated the factor structure and correlates of posttraumatic stress-disorder (PTSD) symptoms among children and adolescents confronted with the death of a loved one. Three hundred thirty-two bereaved children and adolescents (aged 8–18; 56.9 % girls) who all received some form of psychosocial support after their loss, completed self-report measures of PTSD, together with measures tapping demographic and loss-related variables, depression, prolonged grief, and functional impairment. Parent-rated indices of impairment were also collected. We first evaluated the fit of six alternative models of the factor structure of PTSD symptoms, using confirmatory factor analyses. Outcomes showed that the 4-factor numbing model from King et al. (Psychological Assessment 10, 90–96, 1998), with distinct factors of reexperiencing, avoidance, emotional numbing, and hyperarousal fit the data best. Of all participants, 51.5 % met DSM-IV criteria for PTSD. PTSD-status and scores on the PTSD factors varied as a function of age and gender, but were unrelated to other demographic and loss-related variables. PTSD-status and scores on the PTSD factors were significantly associated symptom-levels of depression, prolonged grief, and functional impairment. Findings complement prior evidence that the DSM-IV model of the factor structure of PTSD symptoms may not represent the best conceptualization of these symptoms and highlight the importance of addressing PTSD symptoms in children and adolescents seeking help after bereavement.     

Post-Traumatic Stress Disorder Symptoms in United Nations Peacekeepers: An Examination of Factor Structure in Peacekeepers with and without Chronic Pain

Recent factor analytic investigations of post-traumatic stress disorder in military veterans suggest that symptoms are best described by either a hierarchical 2-factor model or a 4-factor inter-correlated model. Other recent evidence suggests that post-traumatic stress disorder and chronic pain are intricately related; however, the nature of this relationship is not well understood. Factor analysis provides one method for clarifying this relationship. In study 1, we compared competing models of post-traumatic stress disorder symptom structure in a sample of 400 male United Nations peacekeepers using confirmatory factor analysis. Results indicated that both the hierarchical 2-factor and the 4-factor inter-correlated models provided good fit to the data. In study 2, the reliability of these models was assessed in 427 male United Nations peacekeepers with chronic back pain and 341 without. Group comparisons of the confirmatory factor analysis results revealed that the structure of the hierarchical 2-factor and 4-factor inter-correlated models both provided good fit to the data in both the chronic back pain and the group without. However, the structure of the models for the group with chronic back pain group differed in significant ways from that of the group without chronic back pain. Post-traumatic stress disorder symptoms in military veterans can be adequately conceptualized using either a hierarchical 2-factor or 4-factor inter-correlated model. Chronic pain has a minimal influence on overall factor structure. The hierarchical 2-factor model, while parsimonious, does not provide the degree of symptom detail provided by the 4-factor inter-correlated model. Implications for conceptualization of post-traumatic stress disorder symptoms for patients with chronic back pain and significant post-traumatic stress disorder symptomatology are discussed.     

An Examination of Posttraumatic Stress Symptoms among Maltreated Multiracial Youth

Symptoms of posttraumatic stress disorder (PTSD) are common among maltreated youth removed from their homes. These symptoms might be particularly evident in multiracial youth, although little research exists on this vulnerable population. A model whereby depression, dissociation, and posttraumatic cognition symptoms contributed to symptoms of PTSD met goodness-of-fit criteria in 160 maltreated multiracial adolescents. Enhanced model fit was found for females and for adolescents 11 to 13 years old. Analyses further revealed that the best predictors of PTSD symptoms were negative cognitions about the world and anhedonia. The findings are discussed within the context of existing theoretical models of PTSD. The results further highlight the importance of ethnically and racially sensitive approaches to assessment and treatment of youth with PTSD symptoms.     

Clarifying the relationship between AS dimensions and PTSD symptom clusters: are negative and positive affectivity theoretically relevant constructs?

The association between anxiety sensitivity (AS) and posttraumatic stress disorder (PTSD) has been established in contemporary literature; however, research is divided over the nature of specific relationships between AS dimensions and PTSD symptoms clusters. Further, a paucity of research has examined the AS and PTSD relationship while accounting for theoretically relevant variables, such as negative (NA) and positive affect (PA). The purpose of the current study was twofold: first, to clarify divergent findings regarding the contribution of AS dimensions to PTSD symptom clusters, and, second, to further assess the relevance of NA and PA within the AS/PTSD relationship. Hierarchal regression analyses showed that, beyond shared variance attributable to NA and PA, AS somatic concerns were significantly associated with three of four PTSD symptom (i.e., reexperiencing, numbing, hyperarousal), AS cognitive concerns were only associated with hyperarousal, and AS socially observable symptoms were not significantly associated with any PTSD symptom clusters. These findings suggest that AS somatic concerns are the most robust predictor of variance within the AS/PTSD relationship and further clarify the theoretical importance of NA and PA within this relationship. Comprehensive results, implication, and directions for future research are discussed.     

A Cross-Lagged Panel Approach to Understanding Social Support and Chronic Posttraumatic Stress Disorder Symptoms in Veterans: Assessment Modality Matters

Although there is a strong and consistent association between social support and posttraumatic stress disorder (PTSD), the directionality of this association has been debated, with some research indicating that social support protects against PTSD symptoms, whereas other research suggests that PTSD symptoms erode social support. The majority of studies in the literature have been cross-sectional, rendering directionality impossible to determine. Cross-lagged panel models overcome many previous limitations; however, findings from the few studies employing these designs have been mixed, possibly due to methodological differences including self-report versus clinician-administered assessment. The current study used a cross-lagged panel structural equation model to explore the relationship between social support and chronic PTSD symptoms over a 1-year period in a sample of 264 Iraq and Afghanistan veterans assessed several years after trauma exposure. Approximately a third of the sample met criteria for PTSD at the baseline assessment, with veterans’ trauma occurring an average of 6 years prior to baseline. Two separate models were run, with one using PTSD symptoms assessed via self-report and the other using clinician-assessed PTSD symptoms. Excellent model fit was found for both models. Results indicated that the relationship between social support and PTSD symptoms was affected by assessment modality. Whereas the self-report model indicated a bidirectional relationship between social support and PTSD symptoms over time, the clinician-assessed model indicated only that baseline PTSD symptoms predicted social support 1 year later. Results highlight that assessment modality is one factor that likely impacts disparate findings across previous studies. Theoretical and clinical implications of these findings are discussed, with suggestions for the growing body of literature utilizing these designs to dismantle this complex association.     

Posttraumatic stress and depression: potential pathways to disease burden among heart failure patients

Background and Objectives: Posttraumatic stress disorder (PTSD) and Major Depressive Disorder (MDD) are associated with high disease burden. Pathways by which PTSD and MDD contribute to disease burden are not understood. Design: Path analysis was used to examine pathways between PTSD symptoms, MDD symptoms, and disease burden among 251 low-income heart failure patients. Methods: In Model 1, we explored the independent relationship between PTSD and MDD symptoms on disease burden. In Model 2, we examined the association of PTSD symptoms and disease burden on MDD symptoms. We also examined indirect associations of PTSD symptoms on MDD symptoms, mediated by disease burden, and of PTSD symptoms on disease burden mediated by MDD symptoms. Results: Disease burden correlated with PTSD symptoms (r = .41; p < .001) and MDD symptoms (r = .43; p < .001) symptoms. Both models fit the data well and displayed comparable fit. MDD symptoms did not mediate the association of PTSD symptoms with disease burden. Disease burden did mediate the relationship between PTSD symptoms and MDD symptoms. Conclusions: Results support the importance of detection of PTSD in individuals with disease. Results also provide preliminary models for testing longitudinal data in future studies.     

Anhedonia and emotional numbing in combat veterans with PTSD

We explored relationships between anhedonia and posttraumatic stress disorder (PTSD) symptom clusters, including their role in predicting psychiatric comorbidity. Our measure of anhedonia was derived from an examination of the latent structure of the Beck Depression Inventory. We found evidence for a two-factor solution, leading to anhedonia and undifferentiated, global depressive symptoms scales. In primary analyses, anhedonia had a unique positive relationship with PTSD's emotional numbing symptoms and minimal relationships with other PTSD symptoms. Upon examining the incremental validity of appetitive functioning (i.e., anhedonia, emotional numbing) over and above aversive functioning (i.e., re-experiencing, avoidance, and hyper-arousal PTSD symptoms) variables, greater emotional numbing increased the likelihood of being diagnosed with a major depressive disorder, and greater anhedonia increased the likelihood of being diagnosed with additional anxiety disorders and to a lesser extent, psychotic disorders. Results were consistent with research on the distinction of appetitive and aversive functioning, providing insight into the nature of PTSD.     

Confirmatory factor analysis of the PTSD Checklist and the Clinician-Administered PTSD Scale in disaster workers exposed to the World Trade Center Ground Zero

Although posttraumatic stress disorder (PTSD) factor analytic research has yielded little support for the DSM-IV 3-factor model of reexperiencing, avoidance, and hyperarousal symptoms, no clear consensus regarding alternative models has emerged. One possible explanation is differential instrumentation across studies. In the present study, the authors used confirmatory factor analysis to compare a self-report measure, the PTSD Checklist (PCL), and a structured clinical interview, the Clinician-Administered PTSD Scale (CAPS), in 2,960 utility workers exposed to the World Trade Center Ground Zero site. Although two 4-factor models fit adequately for each measure, the latent structure of the PCL was slightly better represented by correlated reexperiencing, avoidance, dysphoria, and hyperarousal factors, whereas that of the CAPS was slightly better represented by correlated reexperiencing, avoidance, emotional numbing, and hyperarousal factors. After accounting for method variance, the model specifying dysphoria as a distinct factor achieved slightly better fit. Patterns of correlations with external variables provided additional support for the dysphoria model. Implications regarding the underlying structure of PTSD are discussed.     

Personal assessment of intimacy in relationships: Validity and measurement invariance across gender

IntroductionIntimacy is central in close relationships and a variety of definitions and instruments exist in scientific literature, making this concept complex to investigate. Furthermore, gender differences were identified in the definition and experience of intimacy.ObjectivesThis study aims to confirm the three-factor structure of the personal assessment of intimacy in relationships (PAIR, Schaefer & Olson, 1981), commonly used in research and marital therapy, developed by Moore et al. (1998) and to examine the measurement equivalence of the scale across gender.MethodA confirmatory factor analysis (CFA) was performed on the responses of 313 women and 251 men in committed relationships in a French population. Measurement equivalence of the scale across gender was then conducted with the best-fitting model.ResultsThe results of CFA and post-hoc analyses revealed that the three-factor model revised with 18 items was the best fit to the data: (1) engagement (10 items), (2) communication (5 items), (3) shared friends (3 items). PAIR-18 displayed a lack of metric and scalar invariance across gender but estimated means of latent variables is not very different between the full invariant model and the unconstraint models.ConclusionNevertheless, consideration of gender differences in the construct of intimacy is very important for theoretical research on intimacy in romantic relationships and for the interventions of marital therapists based on intimacy.     

Comparing posttraumatic stress disorder's symptom structure between deployed and nondeployed veterans

We tested two empirically validated 4-factor models of posttraumatic stress disorder (PTSD) symptoms using the PTSD Checklist: King, Leskin, King, and Weathers' (1998) model including reexperiencing, avoidance, emotional numbing, and hyperarousal factors, and Simms, Watson, and Doebbeling's (2002) model including reexperiencing, avoidance, dysphoria, and hyperarousal. Our aim was to determine which fit better in two groups of military veterans: peacekeepers previously deployed to a war zone (deployed group) and those trained for peacekeeping operations who were not deployed (nondeployed group). We compared the groups using multigroup confirmatory factor analysis. Adequate model fit was demonstrated among the nondeployed group, with no significant difference between King et al.'s (1998) model (separating avoidance and numbing) and Simms et al.'s (2002) similar model involving a dysphoria factor. A better fitting factor structure consistent with Simms et al.'s (2002) model was found in the deployed group. Comprehensive measurement invariance testing demonstrated significant differences between the deployed and nondeployed groups on all structural parameters, except observed variable intercepts (thus indicating similarities only in PTSD item severity). These findings add to researchers' understanding of PTSD's factor structure, given the revision of PTSD that will appear in the forthcoming 5th edition of the Diagnostic and Statistical Manual of Mental Disorders (American Psychiatric Association, 2010)--namely, that the factor structure may be quite different between groups with and without exposure to major traumatic events.     

The Relationship Between a Hierarchical Transdiagnostic Model of Vulnerability Factors and Posttraumatic Stress Disorder Symptom Clusters

The latent structure of Post-Traumatic Stress Disorder (PTSD) symptomology is the subject of ongoing deliberation. The cognitive vulnerabilities of Negative Affect, Anxiety Sensitivity and Intolerance of Uncertainty have been shown to explain symptoms clusters in multiple anxiety and mood disorders, and may be able to offer further insight to explain PTSD symptomology. Using structural equation modelling, this study examines whether a hierarchical model consisting of the general cognitive factor of Negative Affect and the transdiagnostic risk factors of Anxiety Sensitivity and Intolerance of Uncertainty can explain variability among PTSD symptom clusters as defined by the DSM-5 and/or Dysphoria models of PTSD. Anxiety Sensitivity and Intolerance of Uncertainty were tested as mid-level factors between Negative Affect and the PTSD symptom constructs. The hierarchical model fit the data well in both the DSM-5 and Dysphoria models. Negative Affect consistently showed significant direct effects on each symptoms cluster in both models. Anxiety Sensitivity served as a significant mediator of Negative Affect for several symptom clusters in both models. Intolerance of Uncertainty was non-significant either as a direct effect or as a mediator of Negative Affect in all analyses. This study demonstrates how the hierarchical model of Negative Affect, Anxiety Sensitivity and Intolerance of Uncertainty may fit upon multiple PTSD symptom constructs and offers new directions for conceptualizing this disorder.

     

The underlying dimensions of DSM-5 posttraumatic stress disorder (PTSD) and their relationships with mental and somatoform dissociation,depression and anxiety among jail inmates

ABSTRACT

In this study we examined the DSM-5 factor structure of scores on the Turkish version of the posttraumatic stress disorder (PTSD) Checklist for DSM–5 (PCL-5) and predictors of PTSD caseness in a sample of male prisoners. The 7-factor hybrid model was the optimal model relative to the alternatives. Consistent with the PTSD literature in prisoners, the majority of respondents had past traumatic experiences (96.7%), a probable PTSD diagnosis (68.4%), pathological dissociation (46.8%) and somatoform dissociation (52.3%). Probable PTSD caseness was significantly associated with dissociation and depression, as well as higher levels of education and being married. Re-experiencing was strongly associated with mental and somatic dissociation; whereas dysphoric arousal was related to depression and anxiety.     

Anxiety sensitivity and distress tolerance typologies and relations to posttraumatic stress disorder: A cluster analytic approach

A growing literature suggests a relationship between a high anxiety sensitivity (AS; the fear of anxiety and its related consequences)/low distress tolerance (DT; the capacity tolerate internal negative states) profile and posttraumatic stress disorder (PTSD) symptoms. However, specific profiles have not been identified or examined specifically in Veteran samples. Thus, the aims of the present study were to establish empirically derived profiles created from response patterns on the Anxiety Sensitivity Index and Distress Tolerance Scale and to examine associations with PTSD symptom clusters among a sample of combat-exposed Veterans (N = 250). A cluster analytic approach was used to identify AS/DT profiles, and a series of multivariate analyses of variance with post hoc analyses was conducted to examine the relationship between each AS/DT profile and each PTSD symptom cluster. Results indicated a 3-cluster solution including a high AS/low DT “at risk” profile, a low AS/high DT “resilient” profile, and an average AS/DT “intermediate” profile. The at-risk profile was associated with significantly greater symptoms in each PTSD cluster (i.e., hyperarousal, avoidance, re-experiencing) when compared to the other two profiles. The at-risk profile was also associated with greater depressive symptoms and lower self-reported resilience. These findings extend the previous literature by identifying a high AS/low DT “at risk” profile and its associations with PTSD symptoms, underscoring the potential utility in targeting these affect-regulation constructs for clinical intervention.     

<Emphasis Type="Italic">DSM-5</Emphasis> Posttraumatic Stress Disorder Symptom Structure in Disaster-Exposed Adolescents: Stability across Gender and Relation to Behavioral Problems

Given the significant modifications to posttraumatic stress disorder (PTSD) symptom criteria from DSM-IV to DSM-5, a better understanding of the dimensionality underlying DSM-5 PTSD symptoms among adolescents is needed. However, to date, whether gender moderates the latent structure of DSM-5 PTSD symptoms in youth remains unclear. Meanwhile, little is known about how distinct PTSD dimensions relate to adolescent behavioral problems. The aim of this study was to fill these gaps. A sample of 1184 disaster-exposed Chinese adolescents (53.8 % girls) with age ranging from 13 to 17 years (M = 14.3, SD = 0.8) completed the PTSD Checklist for DSM-5, and the Withdrawn, Aggressive Behavior, and Delinquent Behavior subscales of the Youth Self-Report. Confirmatory factor analyses revealed that the seven-factor hybrid PTSD model provided the best fit to the data for both girls and boys. Measurement equivalence of this model held across gender, although girls had higher mean scores than boys on some factors. Differential patterns of associations emerged between PTSD dimensions and behavioral problems, with anhedonia symptoms most strongly relating to social withdrawal, and externalizing behavior symptoms most strongly relating to aggression and delinquency. These findings further support the gender invariance and external criterion validity of the newly refined hybrid model that best represents DSM-5 PTSD symptom structure in youth, and carry implications for accurate assessment, diagnosis, and gender comparison of DSM-5 PTSD symptomatology, and potential symptom targets for PTSD intervention among adolescent disaster survivors.     

PTSD and substance-related problems: the mediating roles of disconstraint and negative emotionality

The authors examined competing hypotheses regarding the role of 2 personality dimensions, disconstraint and negative emotionality, in mediating the relationship between posttraumatic stress disorder (PTSD) severity and substance-related problems. Data were drawn from a large sample of male Vietnam veterans. The best-fitting structural model included significant indirect paths from PTSD to both alcohol- and drug-related outcomes through disconstraint, and a significant indirect path from PTSD to alcohol-related problems through negative emotionality. There were no direct effects of PTSD on either substance-related outcome. These findings indicate distinct pathways to different forms of substance-related problems in PTSD and underscore the role of personality in mediating these relationships.     

Dimensionality of posttraumatic stress symptoms: a confirmatory factor analysis of DSM-IV symptom clusters and other symptom models

Recent exploratory [Taylor, S., Kuch, K., Koch, W. J., Crockett, D. J., & Passey, G. (1998). The structure of posttraumatic stress symptoms. Journal of Abnormal Psychology, 107, 154-160.] and confirmatory [Buckley, T. C., Blanchard, E. B., & Hickling, E. J. (1998). A confirmatory factor analysis of posttraumatic stress symptoms. Behaviour Research and Therapy, 36, 1091-1099; King, D. W., Leskin, G. A., King, L. A., & Weathers, F. W. (1998). Confirmatory factor analysis of the clinician-administered PTSD scale: evidence for the dimensionality of posttraumatic stress disorder. Psychological Assessment, 10, 90-96.] factor analytic investigations suggest that the three symptom clusters of posttraumatic stress disorder (PTSD) as defined in the Diagnostic and Statistical Manual [4th ed.; DSM-IV; American Psychiatric Association (1994). Diagnostic and statistical manual of mental disorders (4th ed.). Washington, DC: Author.] may not provide the best conceptualization of symptom dimensionality. However, the alternative models have not been in agreement, nor have they been compared against each other or models based on the DSM-IV. The purpose of the present investigation was to test a series of dimensional models suggested by these recent factor analytic investigations and the DSM-IV. Using data collected with the PTSD Checklist--Civilian Version [Weathers, F. W., Litz, B. T., Huska, J. A., & Keane, T. M. (1994). PCL-C for DSM-IV. Boston: National Center for PTSD--Behavioral Science Division.] from 349 referrals to a primary care medical clinic, we used confirmatory factor analysis to evaluate a: (1) hierarchical four-factor model, (2) four-factor intercorrelated model, (3) hierarchical three-factor model, (4) three-factor intercorrelated model, and (5) hierarchical two-factor model. The hierarchical four-factor model (comprising four first-order factors corresponding to reexperiencing, avoidance, numbing, and hyperarousal all subsumed by a higher-order general factor) provided the best overall fit to the data; although, all models met some standards specified for good model fit. More research is needed to establish the dimensional nature of PTSD symptoms and to assess whether identified dimensions differ as a function of the trauma experience. Implications for assessment, diagnosis, and treatment are also discussed.     

Testing motivational and self-regulatory mechanisms of action on device-measured physical activity in the context of a weight loss maintenance digital intervention: A secondary analysis of the NoHoW trial

BackgroundTo date, few digital behavior change interventions for weight loss maintenance focusing on long-term physical activity promotion have used a sound intervention design grounded on a logic model underpinned by behavior change theories. The current study is a secondary analysis of the weight loss maintenance NoHoW trial and investigated putative mediators of device-measured long-term physical activity levels (six to 12 months) in the context of a digital intervention.MethodsA subsample of 766 participants (Age = 46.2 ± 11.4 years; 69.1% female; original NoHoW sample: 1627 participants) completed all questionnaires on motivational and self-regulatory variables and had all device-measured physical activity data available for zero, six and 12 months. We examined the direct and indirect effects of Virtual Care Climate on post intervention changes in moderate-to-vigorous physical activity and number of steps (six to 12 months) through changes in the theory-driven motivational and self-regulatory mechanisms of action during the intervention period (zero to six months), as conceptualized in the logic model.ResultsModel 1 tested the mediation processes on Steps and presented a poor fit to the data. Model 2 tested mediation processes on moderate-to-vigorous physical activity and presented poor fit to the data. Simplified models were also tested considering the autonomous motivation and the controlled motivation variables independently. These changes yielded good results and both models presented very good fit to the data for both outcome variables. Percentage of explained variance was negligible for all models. No direct or indirect effects were found from Virtual Care Climate to long term change in outcomes. Indirect effects occurred only between the sequential paths of the theory-driven mediators.ConclusionThis was one of the first attempts to test a serial mediation model considering psychological mechanisms of change and device-measured physical activity in a 12-month longitudinal trial. The model explained a small proportion of variance in post intervention changes in physical activity. We found different pathways of influence on theory-driven motivational and self-regulatory mechanisms but limited evidence that these constructs impacted on actual behavior change. New approaches to test these relationships are needed. Challenges and several alternatives are discussed.Trial registrationISRCTN Registry, ISRCTN88405328. Registered December 16, 2016, https://www.isrctn.com/ISRCTN88405328.