Reward processing in major depressive disorder and prediction of treatment response - Neuropharm study

Major depressive disorder (MDD) is a prevalent brain disorder for which anhedonia is a core symptom, indicating aberrations in the neural processing of reward. The striatum, medial prefrontal cortex (mPFC) and anterior insula (AI) are core reward processing regions. Here we used a reward-related, card-guessing functional magnetic resonance imaging (fMRI) paradigm to assay brain responses to reward in 90 MDD individuals and 58 healthy controls. We evaluated group differences in task-responsive, reward-related striatal, mPFC, and AI reactivity and whether baseline reactivity predicted an eight-week escitalopram antidepressant treatment response in MDD individuals. Thirty-eight MDD individuals also completed the reward paradigm after treatment and we evaluated antidepressant effects on reward reactivity estimates. Multivariate statistical analysis of task-responsive striatum, mPFC and AI brain responses did not reveal statistically significant differences between MDD and HC individuals (p_uncorrected>0.23). Logistic regression models (five-fold cross-validation, statistical significance assessed with permutation testing) also did not support that baseline reward-related brain responses significantly predicted antidepressant treatment response (p_uncorrected>0.39). Finally, reward-related brain responses were not statistically significantly changed over the course of treatment (p_uncorrected>0.27). Our findings in a comparatively large MDD cohort do not support that these reward-related fMRI brain responses are informative biomarkers of MDD or antidepressant treatment response to escitalopram.

Examination of preliminary behavioral and effective connectivity findings from treatment response to citalopram in cocaine use disorder: A dynamic causal modeling study

We sought effective (directional) connectivity parameters associated with response to citalopram in cocaine use disorder (CUD) by conducting a functional magnetic resonance imaging (fMRI) experiment with participants diagnosed with CUD (n = 13) and matched healthy controls (HC; n = 17). CUD participants showed a positive correlation between bilateral DLPFC-to-putamen effective connectivity and treatment effectiveness score. These preliminary results support further investigation of prefrontal-striatal interactions in response to treatment in CUD.

Frontocingulate cerebral blood flow and cerebrovascular reactivity associated with antidepressant response in late-life depression

BACKGROUND

Vascular pathology is common in late-life depression (LLD) and may contribute to alterations in cerebral blood flow (CBF) and cerebrovascular reactivity (CVR). In turn, such hemodynamic deficits may adversely affect brain function and clinical course. The goal of this study was to examine whether altered cerebral hemodynamics in depressed elders predicted antidepressant response.

METHODS

21 depressed elders completed cranial 3T MRI, including a pseudo-continuous Arterial Spin Labeling (pcASL) acquisition on both room air and during a hypercapnia challenge. Participants then completed 12 weeks of open-label sertraline. Statistical analyses examined the relationship between regional normalized CBF and CVR values and change in Montgomery-Asberg Depression Rating Scale (MADRS) and tested for differences based on remission status.

RESULTS

10 participants remitted and 11 did not. After controlling for age and baseline MADRS, greater change in MADRS with treatment was associated with lower pre-treatment normalized CBF in the caudal anterior cingulate cortex (cACC) and lateral orbitofrontal cortex (OFC), as well as lower CVR with hypercapnia in the caudal medial frontal gyrus (cMFG). After controlling for age and baseline MADRS score, remitters exhibited lower CBF in the cACC and lower CVR in the cMFG.

LIMITATIONS

Our sample was small, did not include a placebo arm, and we examined only specific regions of interest.

CONCLUSIONS

Our findings suggest that increased perfusion of the OFC and the ACC is associated with a poor antidepressant response. They do not support that vascular pathology as measured by CBF and CVR negatively affects acute treatment outcomes.