Results of neuroimaging datasets aggregated from multiple sites may be biased by site-specific profiles in participants' demographic and clinical characteristics, as well as MRI acquisition... Show moreResults of neuroimaging datasets aggregated from multiple sites may be biased by site-specific profiles in participants' demographic and clinical characteristics, as well as MRI acquisition protocols and scanning platforms. We compared the impact of four different harmonization methods on results obtained from analyses of cortical thickness data: (1) linear mixed-effects model (LME) that models site-specific random intercepts (LME INT), (2) LME that models both site-specific random intercepts and age-related random slopes (LME INT+ SLP), (3) ComBat, and (4) ComBat with a generalized additive model (ComBat-GAM). Our test case for comparing harmonization methods was cortical thickness data aggregated from 29 sites, which included 1,340 cases with posttraumatic stress disorder (PTSD) (6.2-81.8 years old) and 2,057 trauma-exposed controls without PTSD (6.3-85.2 years old). We found that, compared to the other data harmonization methods, data processed with ComBat-GAM was more sensitive to the detection of significant case-control differences (X-2 (3) = 63.704, p < 0.001) as well as casecontrol differences in age-related cortical thinning (X-2 (3) = 12.082, p = 0.007). Both ComBat and ComBat-GAM outperformed LME methods in detecting sex differences (X-2 (3) = 9.114, p = 0.028) in regional cortical thickness. ComBat-GAM also led to stronger estimates of age-related declines in cortical thickness (corrected p-values < 0.001), stronger estimates of case-related cortical thickness reduction (corrected p-values < 0.001), weaker estimates of age-related declines in cortical thickness in cases than controls (corrected p-values < 0.001), stronger estimates of cortical thickness reduction in females than males (corrected p-values < 0.001), and stronger estimates of cortical thickness reduction in females relative to males in cases than controls (corrected p-values < 0.001). Our results support the use of ComBat-GAM to minimize confounds and increase statistical power when harmonizing data with non-linear effects, and the use of either ComBat or ComBat-GAM for harmonizing data with linear effects. Show less
Eshuis, L.V.; Gelderen, M.J. van; Zuiden, M. van; Nijdam, M.J.; Vermetten, E.; Olff, M.; Bakker, A. 2021
Background: Virtual reality exposure therapy (VRET) and augmented reality exposure therapy (ARET) are digitally assisted psychotherapies that potentially enhance posttraumatic stress disorder (PTSD... Show moreBackground: Virtual reality exposure therapy (VRET) and augmented reality exposure therapy (ARET) are digitally assisted psychotherapies that potentially enhance posttraumatic stress disorder (PTSD) treatment by increasing a patient's sense of presence during exposure therapy. This study aimed to systematically review current evidence regarding the efficacy of VRET and ARET as PTSD treatment. Methods: A systematic electronic database search, a systematic quality assessment and two meta-analyses were conducted in accordance with PRISMA guidelines. Results: Eleven studies on the efficacy of VRET for PTSD (n = 438) were found, but no studies on the efficacy of ARET. The majority of VRET studies were of a low quality and had heterogeneous results. Meta-analyses showed VRET outperformed waitlist control (standardized mean difference -0.64 (95% CI -1.05 to -0.22)) while no significant difference was found between VRET and active treatment conditions (standardized mean difference -0.25 (95% CI -0.77 to 0.27)). Conclusion: VRET was superior to waitlist control groups and as effective as other psychotherapies. However, the results showed considerable heterogeneity due to the low number of studies and variety of VRET methods. VRET may be an effective alternative to current treatments and shows promise for the treatment of PTSD patients that have not responded to previous treatment. Future research should focus on high quality RCTs, including information on side effects and adverse events, with sufficient numbers of participants. This study recognizes a research gap regarding the efficacy of ARET, while it may have potential for PTSD treatment. Show less
Zuiden, M. van; Kavelaars, A.; Vermetten, E.; Olff, M.; Geuze, E.; Heijnen, C. 2015
