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Moderators and predictors of response to cognitive-behavioral therapy augmentation of pharmacotherapy in obsessive–compulsive disorder
- M. J. Maher, J. D. Huppert, H. Chen, N. Duan, E. B. Foa, M. R. Liebowitz, H. B. Simpson
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- Journal:
- Psychological Medicine / Volume 40 / Issue 12 / December 2010
- Published online by Cambridge University Press:
- 26 April 2010, pp. 2013-2023
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- Article
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Background
Cognitive-behavioral therapy (CBT) consisting of exposure and response prevention (EX/RP) is efficacious as a treatment for obsessive–compulsive disorder (OCD). However, about half of patients have a partial or poor response to EX/RP treatment. This study examined potential predictors and moderators of CBT augmentation of pharmacotherapy, to identify variables associated with a poorer response to OCD treatment.
MethodData were drawn from a large randomized controlled trial that compared the augmenting effects of EX/RP to stress management training (SMT; an active CBT control) among 108 participants receiving a therapeutic dose of a serotonin reuptake inhibitor (SRI). Stepwise regression was used to determine the model specification.
ResultsPretreatment OCD severity and gender were significant moderators of outcome: severity affected SMT (but not EX/RP) outcome; and gender affected EX/RP (but not SMT) outcome. Adjusting for treatment type and pretreatment severity, significant predictors included greater co-morbidity, number of past SRI trials, and lower quality of life (QoL). Significant moderators, including their main-effects, and predictors accounted for 37.2% of the total variance in outcome, comparable to the impact of treatment type alone (R2=30.5%). These findings were replicated in the subgroup analysis of EX/RP alone (R2=55.2%).
ConclusionsThis is the first randomized controlled study to examine moderators and predictors of CBT augmentation of SRI pharmacotherapy. Although effect sizes for individual predictors tended to be small, their combined effect was comparable to that of treatment. Thus, future research should examine whether monitoring for a combination of these risk factors and targeting them with multi-modular strategies can improve EX/RP outcome.
Postcumulus processes in layered intrusions
- R. S. J. Sparks, H. E. Huppert, R. C. Kerr, D. P. McKenzie, S. R. Tait
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- Journal:
- Geological Magazine / Volume 122 / Issue 5 / September 1985
- Published online by Cambridge University Press:
- 01 May 2009, pp. 555-568
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During the postcumulus stage of solidification in layered intrusions, fluid dynamic phenomena play an important role in developing the textural and chemical characteristics of the cumulate rocks. One mechanism of adcumulus growth involves crystallization at the top of the cumulate pile where crystals are in direct contact with the magma reservoir. Convection in the chamber can enable adcumulus growth to occur to form a completely solid contact between cumulate and magma. Another important process may involve compositional convection in which light differentiated melt released by intercumulus crystallization is continually replaced by denser melt from the overlying magma reservoir. This process favours adcumulus growth and can allow adcumulus growth within the pore space of the cumulate pile. Calculations indicate that this process could reduce residual porosities to a few percent in large layered intrusions, but could not form pure monomineralic rocks. Intercumulus melt may also be replaced by more primitive melt during episodes of magma chamber replenishment. Dense magma, emplaced over a cumulate pile containing lower density differentiated melt may sink several metres into the underlying pile in the form of fingers. Reactions between melt and matrix may lead to changes in mineral compositions, mineral textures and whole rock isotope compositions. Another important mechanism for forming adcumulate rocks is compaction, in which the imbalance of the hydrostatic and lithostatic pressures in the cumulate pile causes the crystalline matrix to deform and intercumulus melt to be expelled. For cumulate layers from 10 to 1000 metres in thickness, compaction can reduce porosities to very low values (< 1%) and form monomineralic rocks. The characteristic time-scale for such compaction is theoretically short compared to the time required to solidify a large layered intrusion. During compaction changes of mineral compositions and texture may occur as moving melts interact with the surrounding matrix. Both compaction and compositional convection can be interrupted by solidification in the pore spaces. Compositional convection will only occur if the Rayleigh number is larger than 40, if the residual melt becomes lower in density, and the convective velocity exceeds the solidification velocity (measured by the rate of crystal accumulation in the chamber). Orthocumulates are thus more likely to form in rapidly cooled intrusions where residual melt is frozen into the pore spaces before it can be expelled by compaction or replaced by convection.