Mindfulness Training-Induced Increases in Middle Cingulate Cortex Activity during Self-Reflection Predicts Depression-Reduction in Adults with Autism Spectrum Disorder

Background: Adults with autism spectrum disorder (ASD) experience high rates of depression and anxiety. There is some evidence that Mindfulness-Based Stress Reduction (MBSR) is effective in reducing depression and anxiety in adults with ASD, however the neural mechanisms and benefit above and beyond support/education groups are unknown. Functional MRI (fMRI) research shows adults with ASD do not activate the ventral medial prefrontal cortex (vmPFC) and middle cingulate cortex (MCC) during self-reflection as seen in neurotypical (NT) adults. Mindfulness training regulates self-reflection neural activation in NT adults, making this a likely mediator of symptom-reducing effects in adults with ASD.

Objectives: In a pilot study, we investigated whether adults with ASD who received MBSR training increased the blood-oxygen-level dependent (BOLD) response in regions activated during self-reflection, compared to a support/education control group, and if the BOLD signal change correlated with changes in self-reported depression and anxiety.

Methods: Twenty-eight adults (nine women; mean age=31.8±12.9, range=18-64; mean IQ=106±18.5, range=70-139) with ASD were randomly assigned to an 8-week MBSR group (n=15) or a support/education control group (n=13). All participants self-reported an ASD diagnosis and met ASD criteria on the ADOS-2. The MBSR training was adapted by removing metaphorical language similar to Spek et al. (2013), and was co-instructed by an experienced MBSR instructor and ASD clinician. Participants met for two-hours once/week for eight weeks with homework. The novel control group met for the same amount of time with a cognitive neuroscience instructor to control for social interaction/support. Control participants were given minimal education on relaxation techniques from the National Center for Complementary and Integrative Health and homework. Pre- and post-intervention fMRI scans were collected for the self-reflection task where participants: (1) reflected on whether or not the word displayed was a trait they possessed (self-condition), and (2) made a judgement about the positive or negative valence of words (word-condition). Self-reported symptom ratings were assessed via the Beck Depression Inventory-2 and the State-Trait Anxiety Inventory. Within group comparisons were performed with paired t-tests and correlations with Pearson product-moment.

Results: The MBSR group demonstrated significant depression reduction with a moderately-large effect size (t(14)=3.31, p=0.005, d=0.66; Fig. 1a). The control group’s depression reduction approached significance with a moderately-small effect size (t(12)=1.82, p=0.09, d=0.40; Fig. 1a). Neither group significantly reduced anxiety symptoms (Fig. 1b). The MBSR group demonstrated increased activation in MCC (p=0.018, small-volume family-wise error corrected; Fig. 2a), but not vmPFC, in the Self>Word contrast after training; the control group demonstrated no changes. Change in MCC activation was negatively correlated with depressive symptom change in the MBSR group (r(11)=-0.49, p=0.04 one-tailed; Fig. 2b).

Conclusions: In a pilot study, we demonstrated that MBSR is effective for reducing depression in adults with ASD, and the neural mechanism may be increased MCC activation during self-reflection. Additionally, our novel support/education group shows promise for modest depression-reduction, which is an important consideration for individuals or communities with limited access to or funding for MBSR training. A larger clinical trial is warranted to fully understand the efficacy and neural mechanisms of each behavioral intervention.