Brexanolone Treatment in a Real-World Patient Population: A Case Series and Pilot Feasibility Study of Precision Neuroimaging

PURPOSE/BACKGROUND

Brexanolone is approved for postpartum depression (PPD) by the United States Food and Drug Administration. Brexanolone has outperformed placebo in clinical trials, but less is known about the efficacy in real-world patients with complex social and medical histories. Furthermore, the impact of brexanolone on large-scale brain systems such as changes in functional connectivity (FC) is unknown.

METHODS/PROCEDURES

We tracked changes in depressive symptoms across a diverse group of patients who received brexanolone at a large medical center. Edinburgh Postnatal Depression Scale (EPDS) scores were collected through chart review for 17 patients immediately prior to infusion through approximately 1 year postinfusion. In 2 participants, we performed precision functional neuroimaging (pfMRI), including before and after treatment in 1 patient. pfMRI collects many hours of data in individuals for precision medicine applications and was performed to assess the feasibility of investigating changes in FC with brexanolone.

FINDINGS/RESULTS

The mean EPDS score immediately postinfusion was significantly lower than the mean preinfusion score (mean change [95% CI]: 10.76 [7.11-14.40], t (15) = 6.29, P < 0.0001). The mean EPDS score stayed significantly lower at 1 week (mean difference [95% CI]: 9.50 [5.23-13.76], t (11) = 4.90, P = 0.0005) and 3 months (mean difference [95% CI]: 9.99 [4.71-15.27], t (6) = 4.63, P = 0.0036) postinfusion. Widespread changes in FC followed infusion, which correlated with EPDS scores.

IMPLICATIONS/CONCLUSIONS

Brexanolone is a successful treatment for PPD in the clinical setting. In conjunction with routine clinical care, brexanolone was linked to a reduction in symptoms lasting at least 3 months. pfMRI is feasible in postpartum patients receiving brexanolone and has the potential to elucidate individual-specific mechanisms of action.

Neural correlates of drinking reduction during a clinical trial of cognitive behavioral therapy for alcohol use disorder

BACKGROUND

Cognitive behavioral therapy (CBT) is an effective treatment for alcohol use disorder (AUD). We hypothesized that the dorsolateral prefrontal cortex (DLPFC), a region implicated in cognitive control and goal-directed behavior, plays a role in behavior change during CBT by facilitating the regulation of craving (ROC).

METHODS

Treatment-seeking participants with AUD (N = 22) underwent functional magnetic resonance imaging (fMRI) scanning both before and after a 12-week, single-arm trial of CBT, using an ROC task that was previously shown to engage the DLPFC.

RESULTS

We found that both the percentage of heavy drinking days (PHDD) and the overall self-reported alcohol craving measured during the ROC task were significantly reduced from pre- to post-CBT. However, we did not find significant changes over time in either the ability to regulate craving or regulation-related activity in any brain region. We found a significant 3-way interaction between the effects of cue-induced craving, cue-induced brain activity and timepoint of assessment (pre- or post-CBT) on PHDD in the left DLPFC. Follow-up analysis showed that cue-induced craving was associated with cue-induced activity in the left DLPFC among participants who ceased heavy drinking during CBT, both at pre-CBT and post-CBT timepoints. No such associations were present at either timepoint among participants who continued to drink heavily.

CONCLUSIONS

These results suggest that patients in whom DLPFC functioning is more strongly related to cue-induced craving may preferentially respond to CBT.

A Novel Cognitive Training Program Targets Stimulus-Driven Attention to Alter Symptoms, Behavior, and Neural Circuitry in Pediatric Anxiety Disorders: Pilot Clinical Trial

Objective: Pediatric anxiety disorders are associated with increased stimulus-driven attention (SDA), the involuntary capture of attention by salient stimuli. Increased SDA is linked to increased activity in the right ventrolateral prefrontal cortex (rVLPFC), especially in the portion corresponding to the ventral attention network (VAN). In this study, we present a small clinical trial using a novel attention training program designed to treat pediatric anxiety by decreasing SDA and activity in the rVLPFC. Methods: Children ages 8-12 with anxiety disorders (n = 18) participated in eight sessions of attention training over a 4-week period. At baseline and after completing training, participants completed clinical anxiety measures and a battery of cognitive tasks designed to measure three different aspects of attention: SDA, goal-oriented attention, and threat bias. A subset of participants (n = 12) underwent baseline and post-training neuroimaging while engaged in an SDA task. Brain analyses focused on activity within the rVLPFC. Results: Parent (p < 0.001)-, child (p < 0.002)-, and clinician-rated (p < 0.02) anxiety improved significantly over the course of training. Training significantly altered SDA [F(1,92) = 8.88, corrected p-value (pcor) < 0.012, uncorrected p-value (puncor) < 0.004]. Anxiety improvement correlated with improvements in goal-directed attention [r(10) = 0.60, pcor < 0.12 puncor < 0.04]. Within an area of the rVLPFC corresponding to the cingulo-opercular network (CON), there was a main effect of training [F(1,20) = 6.75, pcor < 0.16, puncor < 0.02], with decreasing signal across training. There was a significant interaction between training and anxiety on this region's activity [F(1,20) = 9.48, pcor < 0.048, puncor < 0.006]. Post hoc testing revealed that post-training activity within this CON area correlated with residual anxiety [r(10) = 0.68, p < 0.02]. Conclusions: SDA and rVLPFC neural activity may be novel therapeutic targets in pediatric anxiety. After undergoing a training paradigm aimed at modifying this aspect of attention and its underlying neural circuitry, patients showed lower anxiety, changes in SDA and goal-oriented attention, and decreased activity in the CON portion of the rVLPFC.

Neurocircuitry of Treatment in Anxiety Disorders

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Precision clinical trials: a framework for getting to precision medicine for neurobehavioural disorders

The goal of precision medicine (individually tailored treatments) is not being achieved for neurobehavioural conditions such as psychiatric disorders. Traditional randomized clinical trial methods are insufficient for advancing precision medicine because of the dynamic complexity of these conditions. We present a pragmatic solution: the precision clinical trial framework, encompassing methods for individually tailored treatments. This framework includes the following: (1) treatment-targeted enrichment, which involves measuring patients' response after a brief bout of an intervention, and then randomizing patients to a full course of treatment, using the acute response to predict long-term outcomes; (2) adaptive treatments, which involve adjusting treatment parameters during the trial to individually optimize the treatment; and (3) precise measurement, which involves measuring predictor and outcome variables with high accuracy and reliability using techniques such as ecological momentary assessment. This review summarizes precision clinical trials and provides a research agenda, including new biomarkers such as precision neuroimaging, transcranial magnetic stimulation-electroencephalogram digital phenotyping and advances in statistical and machine-learning models. Validation of these approaches - and then widespread incorporation of the precision clinical trial framework - could help achieve the vision of precision medicine for neurobehavioural conditions.

Individual-specific functional connectivity of the amygdala: A substrate for precision psychiatry

The amygdala is central to the pathophysiology of many psychiatric illnesses. An imprecise understanding of how the amygdala fits into the larger network organization of the human brain, however, limits our ability to create models of dysfunction in individual patients to guide personalized treatment. Therefore, we investigated the position of the amygdala and its functional subdivisions within the network organization of the brain in 10 highly sampled individuals (5 h of fMRI data per person). We characterized three functional subdivisions within the amygdala of each individual. We discovered that one subdivision is preferentially correlated with the default mode network; a second is preferentially correlated with the dorsal attention and fronto-parietal networks; and third subdivision does not have any networks to which it is preferentially correlated relative to the other two subdivisions. All three subdivisions are positively correlated with ventral attention and somatomotor networks and negatively correlated with salience and cingulo-opercular networks. These observations were replicated in an independent group dataset of 120 individuals. We also found substantial across-subject variation in the distribution and magnitude of amygdala functional connectivity with the cerebral cortex that related to individual differences in the stereotactic locations both of amygdala subdivisions and of cortical functional brain networks. Finally, using lag analyses, we found consistent temporal ordering of fMRI signals in the cortex relative to amygdala subdivisions. Altogether, this work provides a detailed framework of amygdala-cortical interactions that can be used as a foundation for models relating aberrations in amygdala connectivity to psychiatric symptoms in individual patients.

Charting the expansion of strategic exploratory behavior during adolescence

Although models of exploratory decision making implicate a suite of strategies that guide the pursuit of information, the developmental emergence of these strategies remains poorly understood. This study takes an interdisciplinary perspective, merging computational decision making and developmental approaches to characterize age-related shifts in exploratory strategy from adolescence to young adulthood. Participants were 149 12-28-year-olds who completed a computational explore-exploit paradigm that manipulated reward value, information value, and decision horizon (i.e., the utility that information holds for future choices). Strategic directed exploration, defined as information seeking selective for long time horizons, emerged during adolescence and maintained its level through early adulthood. This age difference was partially driven by adolescents valuing immediate reward over new information. Strategic random exploration, defined as stochastic choice behavior selective for long time horizons, was invoked at comparable levels over the age range, and predicted individual differences in attitudes toward risk taking in daily life within the adolescent portion of the sample. Collectively, these findings reveal an expansion of the diversity of strategic exploration over development, implicate distinct mechanisms for directed and random exploratory strategies, and suggest novel mechanisms for adolescent-typical shifts in decision making. (PsycINFO Database Record

FAAH genetic variation enhances fronto-amygdala function in mouse and human

Cross-species studies enable rapid translational discovery and produce the broadest impact when both mechanism and phenotype are consistent across organisms. We developed a knock-in mouse that biologically recapitulates a common human mutation in the gene for fatty acid amide hydrolase (FAAH) (C385A; rs324420), the primary catabolic enzyme for the endocannabinoid anandamide. This common polymorphism impacts the expression and activity of FAAH, thereby increasing anandamide levels. Here, we show that the genetic knock-in mouse and human variant allele carriers exhibit parallel alterations in biochemisty, neurocircuitry, and behavior. Specifically, there is reduced FAAH expression associated with the variant allele that selectively enhances fronto-amygdala connectivity and fear extinction learning, and decreases anxiety-like behaviors. These results suggest a gain-of-function in fear regulation and may indicate for whom and for what anxiety symptoms FAAH inhibitors or exposure-based therapies will be most efficacious, bridging an important translational gap between the mouse and human.

Default mode network mechanisms of transcranial magnetic stimulation in depression

BACKGROUND

Repetitive transcranial magnetic stimulation (TMS) of the dorsolateral prefrontal cortex (DLPFC) is an established treatment for depression, but its underlying mechanism of action remains unknown. Abnormalities in two large-scale neuronal networks-the frontoparietal central executive network (CEN) and the medial prefrontal-medial parietal default mode network (DMN)-are consistent findings in depression and potential therapeutic targets for TMS. Here, we assessed the impact of TMS on activity in these networks and their relation to treatment response.

METHODS

We used resting state functional magnetic resonance imaging to measure functional connectivity within and between the DMN and CEN in 17 depressed patients, before and after a 5-week course of TMS. Motivated by prior reports, we focused on connectivity seeded from the DLPFC and the subgenual cingulate, a key region closely aligned with the DMN in depression. Connectivity was also compared with a cohort of 35 healthy control subjects.

RESULTS

Before treatment, functional connectivity in depressed patients was abnormally elevated within the DMN and diminished within the CEN, and connectivity between these two networks was altered. Transcranial magnetic stimulation normalized depression-related subgenual hyperconnectivity in the DMN but did not alter connectivity in the CEN. Transcranial magnetic stimulation also induced anticorrelated connectivity between the DLPFC and medial prefrontal DMN nodes. Baseline subgenual connectivity predicted subsequent clinical improvement.

CONCLUSIONS

Transcranial magnetic stimulation selectively modulates functional connectivity both within and between the CEN and DMN, and modulation of subgenual cingulate connectivity may play an important mechanistic role in alleviating depression. The results also highlight potential neuroimaging biomarkers for predicting treatment response.

Neural Evidence for the Flexible Control of Mental Representations

This study was designed to explore neural evidence for the simultaneous engagement of multiple mental codes while retaining a visual object in short-term memory (STM) and, if successful, to explore the neural bases of strategic prioritization among these codes. We used multivariate pattern analysis of fMRI data to track patterns of brain activity associated with three common mental codes: visual, verbal, and semantic. When participants did not know which dimension of a sample stimulus would be tested, patterns of brain activity during the memory delay indicated that a visual representation was quickly augmented with both verbal and semantic re-representations of the stimulus. The verbal code emerged as most highly activated, consistent with a canonical visual-to-phonological recoding operation in STM. If participants knew which dimension of a sample stimulus would be tested, brain activity patterns were biased toward the probe-relevant stimulus dimension. Interestingly, probe-irrelevant neural states persisted at an intermediate level of activation when they were potentially relevant later in the trial, but dropped to baseline when cued to be irrelevant. These results reveal the neural dynamics underlying the creation and retention of mental codes, and they illustrate the flexible control that humans can exert over these representations.

Teens impulsively react rather than retreat from threat

There is a significant inflection in risk taking and criminal behavior during adolescence, but the basis for this increase remains largely unknown. An increased sensitivity to rewards has been suggested to explain these behaviors, yet juvenile offences often occur in emotionally charged situations of negative valence. How behavior is altered by changes in negative emotional processes during adolescence has received less attention than changes in positive emotional processes. The current study uses a measure of impulsivity in combination with cues that signal threat or safety to assess developmental changes in emotional responses to threat cues. We show that adolescents, especially males, impulsively react to threat cues relative to neutral ones more than adults or children, even when instructed not to respond. This adolescent-specific behavioral pattern is paralleled by enhanced activity in limbic cortical regions implicated in the detection and assignment of emotional value to inputs and in the subsequent regulation of responses to them when successfully suppressing impulsive responses to threat cues. In contrast, prefrontal control regions implicated in detecting and resolving competing responses show an adolescent-emergent pattern (i.e. greater activity in adolescents and adults relative to children) during successful suppression of a response regardless of emotion. Our findings suggest that adolescence is a period of heightened sensitivity to social and emotional cues that results in diminished regulation of behavior in their presence.

Decoding attended information in short-term memory: an EEG study

For decades it has been assumed that sustained, elevated neural activity--the so-called active trace--is the neural correlate of the short-term retention of information. However, a recent fMRI study has suggested that this activity may be more related to attention than to retention. Specifically, a multivariate pattern analysis failed to find evidence that information that was outside the focus of attention, but nonetheless in STM, was retained in an active state. Here, we replicate and extend this finding by querying the neural signatures of attended versus unattended information within STM with electroencephalograpy (EEG), a method sensitive to oscillatory neural activity to which the previous fMRI study was insensitive. We demonstrate that in the delay-period EEG activity, there is information only about memory items that are also in the focus of attention. Information about items outside the focus of attention is not detectable. This result converges with the fMRI findings to suggest that, contrary to conventional wisdom, an active memory trace may be unnecessary for the short-term retention of information.

Neural evidence for a distinction between short-term memory and the focus of attention

It is widely assumed that the short-term retention of information is accomplished via maintenance of an active neural trace. However, we demonstrate that memory can be preserved across a brief delay despite the apparent loss of sustained representations. Delay period activity may, in fact, reflect the focus of attention, rather than STM. We unconfounded attention and memory by causing external and internal shifts of attention away from items that were being actively retained. Multivariate pattern analysis of fMRI indicated that only items within the focus of attention elicited an active neural trace. Activity corresponding to representations of items outside the focus quickly dropped to baseline. Nevertheless, this information was remembered after a brief delay. Our data also show that refocusing attention toward a previously unattended memory item can reactivate its neural signature. The loss of sustained activity has long been thought to indicate a disruption of STM, but our results suggest that, even for small memory loads not exceeding the capacity limits of STM, the active maintenance of a stimulus representation may not be necessary for its short-term retention.