Using Drift Diffusion and RL Models to Disentangle Effects of Depression On Decision-Making vs. Learning in the Probabilistic Reward Task.

The Probabilistic Reward Task (PRT) is widely used to investigate the impact of Major Depressive Disorder (MDD) on reinforcement learning (RL), and recent studies have used it to provide insight into decision-making mechanisms affected by MDD. The current project used PRT data from unmedicated, treatment-seeking adults with MDD to extend these efforts by: (1) providing a more detailed analysis of standard PRT metrics-response bias and discriminability-to better understand how the task is performed; (2) analyzing the data with two computational models and providing psychometric analyses of both; and (3) determining whether response bias, discriminability, or model parameters predicted responses to treatment with placebo or the atypical antidepressant bupropion. Analysis of standard metrics replicated recent work by demonstrating a dependency between response bias and response time (RT), and by showing that reward totals in the PRT are governed by discriminability. Behavior was well-captured by the Hierarchical Drift Diffusion Model (HDDM), which models decision-making processes; the HDDM showed excellent internal consistency and acceptable retest reliability. A separate "belief" model reproduced the evolution of response bias over time better than the HDDM, but its psychometric properties were weaker. Finally, the predictive utility of the PRT was limited by small samples; nevertheless, depressed adults who responded to bupropion showed larger pre-treatment starting point biases in the HDDM than non-responders, indicating greater sensitivity to the PRT's asymmetric reinforcement contingencies. Together, these findings enhance our understanding of reward and decision-making mechanisms that are implicated in MDD and probed by the PRT.

Community-Delivered Heated Hatha Yoga as a Treatment for Depressive Symptoms: An Uncontrolled Pilot Study.

Objectives: There are no known studies of concurrent exposure to high temperature and yoga for the treatment of depression. This study explored acceptability and feasibility of heated (Bikram) yoga as a treatment for individuals with depressive symptoms. Design: An 8-week, open-label pilot study of heated yoga for depressive symptoms. Subjects: 28 medically healthy adults (71.4% female, mean age 36 [standard deviation 13.57]) with at least mild depressive symptoms (Hamilton Rating Scale for Depression [HRSD-17] score ≥10) who attended at least one yoga class and subsequent assessment visit. Intervention: Participants were asked to attend at least twice weekly community held Bikram Yoga classes. Assessments were performed at screening and weeks 1, 3, 5, and 8. Hypotheses were tested using a modified-intent-to-treat approach, including participants who attended at least one yoga class and subsequent assessment visit (N = 28). Results: Almost half of our subjects completed the 8-week intervention, and close to a third attended three quarters or more of the prescribed 16 classes over 8 weeks. Multilevel modeling revealed significant improvements over time in both clinician-rated HRSD-17 (p = 0.003; dGLMM = 1.43) and self-reported Beck Depression Inventory (BDI; p < 0.001, dGLMM = 1.31) depressive symptoms, as well as the four secondary outcomes: hopelessness (p = 0.024, dGLMM = 0.57), anxiety (p < 0.001, dGLMM = 0.78), cognitive/physical functioning (p < 0.001, dGLMM = 1.34), and quality of life (p = 0.007, dGLMM = 1.29). Of 23 participants with data through week 3 or later, 12 (52.2%) were treatment responders (≥50% reduction in HRSD-17 score), and 13 (56.5%) attained remission (HRSD score ≤7). More frequent attendance was significantly associated with improvement in self-rated depression symptoms, hopelessness, and quality of life. Conclusions: The acceptability and feasibility of heated yoga in this particular sample with this protocol warrants further attention. The heated yoga was associated with reduced depressive symptoms, and other improved related mental health symptoms, including anxiety, hopelessness, and quality of life.

Patient primary language in a culturally focused intervention for Latino Americans with depression.

BACKGROUND: This study examined whether a culturally focused psychiatric consultation program (CFP) for Latino Americans was equally effective in reducing depressive symptoms in English-speaking and Spanish-speaking patients. METHODS: The CFP utilizes the Engagement Interview Protocol (EIP), a semi-standardized protocol eliciting patient narratives about illness beliefs. The sample included 118 Latino American patients presenting with depressive symptoms. Patient-preferred primary language was examined as a moderator for the effect of CFP participation vs usual care on change in depressive symptoms. RESULTS: Multiple regression analysis revealed that the interaction effect of primary language and treatment arm on depressive symptoms, as measured by the Quick Inventory of Depressive Symptomatology-Self Report was not statistically significant at 6-month follow-up (B = -2.89, t = -1.35, P = .180). CONCLUSIONS: The findings suggest that the CFP was equally effective in both Spanish and English-speaking Latino Americans. The trend in the results toward greater reduction in depressive symptoms in primary Spanish-speaking Latino Americans as compared with primary English-speaking Latino Americans suggests the importance of receiving language-concordant care.

Val66Met polymorphism association with serum BDNF and inflammatory biomarkers in major depression.

OBJECTIVES: Current evidence supports participation of neurotrophic and inflammatory factors in the pathogenesis of major depressive disorder (MDD). Some studies reported an association between the Val66Met polymorphism (rs6265) of brain-derived neurotrophic factor (BDNF) gene with MDD and peripheral BDNF levels. However, no previous studies have examined the association of this polymorphism with inflammation. The present study assessed the association of the Val66Met polymorphism with serum levels of BDNF and inflammatory markers among depressed outpatients. METHODS: All participants (n = 73) met DSM-IV criteria for a unipolar depressive episode. The serum levels of BDNF and inflammatory biomarkers (IL-2, IL-4, IL-6, IL-10, TNF-α and IFN-γ) were compared between individuals presenting with at least one Met allele (Met-carriers) and those homozygous for the Val allele. RESULTS: In our sample (84.9% female, mean age 52.4 ± 10.3 years), 24.7% (n = 18) were Met-carriers. After Bonferroni correction, the Met allele was significantly associated with higher BDNF and lower TNF-α. These associations persisted after adjusting for potential confounders. CONCLUSIONS: The pattern of low BDNF and high inflammation in MDD may be influenced by the Val66Met polymorphism. The association of a polymorphism in the BDNF gene with inflammatory markers in addition to BDNF levels suggests an interaction between these systems.