Does cannabis use impact cognitive behavioural therapy outcomes for anxiety and related disorders? A preliminary examination.

OBJECTIVES: The current study examined whether cannabis use frequency and cannabis-related problem severity (as per the Cannabis Use Disorder Identification Test-Revised) predicted outcomes of cognitive behavioural therapy (CBT) for anxiety and related disorders. It was predicted that greater frequency of cannabis use and greater cannabis-related problem severity would be associated with dampened treatment outcomes compared to less severe cannabis use presentations. METHODS: Participants were 253 adults seeking treatment for anxiety and related disorders. Cannabis use was categorized as non-use (n = 135), infrequent use (using monthly to 4 times per month; n = 45), and frequent use (using 2 or more times per week; n = 73). Individuals who reported using cannabis completed cannabis use and cannabis-related problem measures before starting a CBT group. Participants also completed a weekly symptom-specific measure of anxiety symptoms throughout CBT. RESULTS: As hypothesized, frequent cannabis use was associated with poorer outcomes in CBT for anxiety and related disorders compared to non-use. Despite this, individuals who used cannabis frequently still experienced a statistically significant decrease in their anxiety symptoms from pre-to post-CBT, with a large effect size (d = -0.87). Cannabis-related problems was not a significant predictor of CBT outcomes. CONCLUSIONS: Cannabis use frequency was associated with poorer CBT outcomes for anxiety and related disorders, however these individuals still made notable treatment gains. The mechanism driving this relationship remains unclear. Future studies should attempt to replicate the current findings and examine possible mechanisms.

Distinct Subcortical Volume Alterations in Pediatric and Adult OCD: A Worldwide Meta- and Mega-Analysis.

OBJECTIVE: Structural brain imaging studies in obsessive-compulsive disorder (OCD) have produced inconsistent findings. This may be partially due to limited statistical power from relatively small samples and clinical heterogeneity related to variation in illness profile and developmental stage. To address these limitations, the authors conducted meta- and mega-analyses of data from OCD sites worldwide. METHOD: T1 images from 1,830 OCD patients and 1,759 control subjects were analyzed, using coordinated and standardized processing, to identify subcortical brain volumes that differ between OCD patients and healthy subjects. The authors performed a meta-analysis on the mean of the left and right hemisphere measures of each subcortical structure, and they performed a mega-analysis by pooling these volumetric measurements from each site. The authors additionally examined potential modulating effects of clinical characteristics on morphological differences in OCD patients. RESULTS: The meta-analysis indicated that adult patients had significantly smaller hippocampal volumes (Cohen's d=-0.13; % difference=-2.80) and larger pallidum volumes (d=0.16; % difference=3.16) compared with adult controls. Both effects were stronger in medicated patients compared with controls (d=-0.29, % difference=-4.18, and d=0.29, % difference=4.38, respectively). Unmedicated pediatric patients had significantly larger thalamic volumes (d=0.38, % difference=3.08) compared with pediatric controls. None of these findings were mediated by sample characteristics, such as mean age or scanning field strength. The mega-analysis yielded similar results. CONCLUSIONS: The results indicate different patterns of subcortical abnormalities in pediatric and adult OCD patients. The pallidum and hippocampus seem to be of importance in adult OCD, whereas the thalamus seems to be key in pediatric OCD. These findings highlight the potential importance of neurodevelopmental alterations in OCD and suggest that further research on neuroplasticity in OCD may be useful.

A preliminary study of functional connectivity of medication naïve children with obsessive-compulsive disorder.

BACKGROUND: Evidence suggests that obsessive-compulsive disorder (OCD) is associated with a dysfunction in the cortico-striatal-thalamic-cortical (CSTC) circuitry. Resting state functional connectivity magnetic resonance imaging (rs-fcMRI) allows measurements of resting state networks (RSNs), brain networks that are present at 'rest'. However, although OCD has a typical onset during childhood or adolescence, only two other studies have performed rs-fcMRI comparisons of RSNs in children and adolescents with OCD against healthy controls. METHODS: In the present study, we performed resting state functional magnetic resonance imaging using a 3 Tesla MRI, in 11 medication-naïve children and adolescents with OCD and 9 healthy controls. In contrast to previous studies that relied on a priori determination of RSNs, we determined resting state functional connectivity with a data-driven independent component analysis (ICA). RESULTS: Consistent with previous reports in healthy adults, we identified 13 RSNs. Case-control un-adjusted statistical significance (p<0.05) was found for two networks. Firstly, increased connectivity (OCD>control) in the right section of Brodmann area 43 of the auditory network; Secondly, decreased connectivity in the right section of Brodmann area 8 and Brodmann area 40 in the cingulate network. CONCLUSIONS: Our preliminary findings of case-control differences in RSNs lend further support to the CSTC hypothesis of OCD, as well as implicating other regions of the brain outside of the CSTC.