Negative Affect Circuit Subtypes and Neural, Behavioral, and Affective Responses to MDMA: A Randomized Clinical Trial

Posttraumatic stress disorder (PTSD) and major depressive disorder (MDD) show substantial clinical and neurobiological heterogeneity, yet treatments are commonly applied through a trial-and-error approach. Zhang and colleagues position precision medicine in mental health as a way to overcome this limitation by stratifying individuals on the basis of neural circuit profiles derived from functional neuroimaging. Prior fMRI work has repeatedly implicated amygdala hyperactivity during nonconscious threat processing in PTSD and MDD; relationships between threat-evoked amygdala responses and ventral anterior cingulate regions, including the subgenual anterior cingulate cortex (sgACC), have varied across studies, suggesting distinct subgroups within these disorders. The amygdala and sgACC comprise a negative affect circuit thought to mediate implicit threat detection and regulation, and amygdala hyperactivity during nonconscious threat has been associated with poorer responses to first-line treatments. This study tested whether baseline stratification by negative affect circuit activity—measured during a nonconscious threat task—differentiates acute neural, behavioural, and affective responses to MDMA. Using a within-participant, double-blinded, placebo- and baseline-controlled design, the investigators administered two MDMA doses (80 mg and 120 mg) and placebo to adults with histories of early life trauma and subthreshold PTSD symptoms. They hypothesised that individuals with higher baseline threat-evoked circuit activity would show normalisation across neural, behavioural, and affective measures following acute MDMA administration compared with those with lower baseline activity. The approach aims to identify potential biomarkers to personalise MDMA-based interventions and clarify MDMA’s standalone pharmacological effects on threat circuitry.

The trial was approved by Stanford University's institutional review board and preregistered; all participants gave written informed consent and the study followed CONSORT guidelines. The investigators used a within-participants, randomised, double-blind design with a true baseline visit preceding any drug exposure. Each participant completed four visits: one baseline session, a placebo session, and two MDMA sessions (80 mg and 120 mg) in randomized order. Data collection for the reported wave occurred between November 2, 2021, and November 9, 2022. Seventeen adults aged 18–55 were recruited from the community. The extracted text does not clearly report exclusion criteria in full here, but elsewhere indicates participants had used MDMA on at least two prior occasions, had not used it in the preceding 6 months, and had subthreshold PTSD symptoms and histories of early life trauma while lacking current psychiatric disorders. The text reports stratification analyses conducted on 16 participants (see Results), so the sample actually analysed is unclear from the extraction. Primary outcomes centred on the negative affect circuit: amygdala and sgACC activity and their connectivity evoked by a nonconscious Facial Expressions of Emotion Task. Task-evoked responses (threat vs neutral faces) were measured by fMRI approximately 90 minutes after drug or placebo administration and expressed as z scores relative to a healthy reference dataset (n = 50). Secondary measures included a behavioural implicit emotion bias test (WebNeuro implicit recognition of facial emotions), where implicit threat bias was operationalised as reaction time for angry minus neutral faces and standardised against age-matched norms; a facial likability rating (0–100) for faces seen in the fMRI task; affective self-report via visual analogue scales (VAS) including items such as "I want to be with other people" and "I feel secure"; and selected subscales of the Five-Dimensional Altered States of Consciousness (5D-ASC) assessing Anxiety and Impaired Control and Cognition. Participants’ narrative descriptions were also recorded. For analysis, the investigators stratified participants at baseline by amygdala response to nonconscious threat using a median split into NTN A+ and NTN A- subgroups. Linear mixed-effects models tested effects of baseline subgroup, dose (placebo, 80 mg, 120 mg), and their interaction, with covariates (age, biological sex, percentage of motion spikes) included when associated with outcomes. The primary contrasts emphasised were placebo versus 120 mg and placebo versus 80 mg. Effect sizes were reported as Cohen's d and statistical significance was set at two-sided P < .05. Multiple imputation was used to address missing values in sensitivity checks. Masking (blinding) integrity was assessed by asking clinicians, coordinators, and participants to identify dose conditions.

Baseline stratification divided participants into NTN A+ (high threat-evoked amygdala activity) and NTN A- (low activity) subgroups using a median split, each with eight participants according to the extracted text. The NTN A+ subgroup had mean amygdala z scores above the healthy reference (mean z = 1.09) while the NTN A- subgroup had mean z below the reference (mean z = -0.57). The NTN A+ subgroup showed significantly greater amygdala activity than the NTN A- subgroup at baseline (mean difference 1.66; 95% CI, 1.00–2.32; Cohen d = 2.7; P < .001). Behaviourally, NTN A+ participants exhibited a larger implicit threat bias at baseline, with slower reaction times when implicitly primed with angry versus neutral faces (mean difference -0.93; 95% CI, -1.61 to -0.26; Cohen d = -1.48; P = .01). The investigators report that these subgroup differences were not attributable to baseline demographics, overall symptom severity, or early life trauma as measured in the study, although a relatively greater distribution of PTSD symptoms and traumatic events was seen in NTN A+ (supplementary figures referenced). For acute drug effects, distinct differences emerged for the 120 mg MDMA dose when compared with placebo in the NTN A+ versus NTN A- subgroups. In the NTN A+ subgroup, 120 mg MDMA produced significant reductions in threat-evoked amygdala activity (contrast estimate [CE] -1.43; 95% CI, -2.60 to -0.27; Cohen d = -1.22; P = .02) and sgACC activity (CE -1.48; 95% CI, -2.42 to -0.54; Cohen d = -1.56; P = .004). The same subgroup also showed an increase in sgACC–right amygdala connectivity (CE 0.65; 95% CI, 0.02–1.28; Cohen d = 1.02; P = .04). These neural changes were specific to the 120 mg dose in the reported comparisons. On behavioural and affective outcomes, implicit threat bias did not differ significantly between subgroups in response to MDMA (CE 0.45; 95% CI, -0.49 to 1.39; Cohen d = 0.38; P = .34). Perceived likability of threat faces, however, increased significantly in the NTN A+ subgroup under 120 mg MDMA compared with NTN A- (CE 14.38; 95% CI, 1.46–27.29; Cohen d = 0.86; P = .03), with effects particularly noted for angry faces. Self-reported affect showed subgroup differences for some items: the extracted text is truncated for one contrast (reporting that NTN A+ reported less increase in "wanting to be with others" with incomplete CI reporting), but it does report no significant increase in Impaired Control and Cognition (CE 11.07; 95% CI, -0.53 to 22.67; Cohen d = 0.74; P = .06). Narrative reports aligned with quantitative measures: NTN A+ participants described more introspective and emotionally nuanced experiences during 120 mg MDMA, whereas NTN A- participants described more positive and euphoric experiences. Results were robust to multiple imputation for missing data according to supplementary analyses. Masking outcomes showed that dose conditions were correctly identified across visits in 85% of clinician ratings (39 of 46), 81% of research coordinator ratings (38 of 47), and 77% of participant ratings (34 of 44). Accuracy was highest for placebo and lower for both MDMA doses; accuracy was notably lower in the NTN A- subgroup (reported range 50%–60% for some conditions).

Zhang and colleagues interpret their findings as evidence that baseline stratification by negative affect circuit activity can differentiate acute neural, behavioural, and affective responses to MDMA. They highlight that, following a single 120 mg dose of MDMA administered in a supportive research environment without structured therapy, participants with high baseline amygdala activity (NTN A+) exhibited reduced amygdala and sgACC activation in response to nonconscious threat and increased amygdala–sgACC connectivity. The investigators view these changes as a regularisation of threat circuitry, consistent with the idea that MDMA pharmacology can dampen automatic threat reactivity and thereby create a neural state more receptive to emotional engagement. The authors situate their results within prior literature showing amygdala hyperactivity during nonconscious threat in PTSD and MDD and note that increased amygdala–sgACC connectivity has been associated with successful extinction of implicit threat conditioning. They propose that the observed connectivity increase may reflect enhanced implicit regulation of threat, promoting more contextualised processing of trauma-related stimuli. Behavioural findings—particularly increased likability ratings of threat faces in the NTN A+ subgroup—are discussed as evidence that MDMA can soften the emotional salience of threat-related cues. At the same time, the NTN A+ subgroup reported some increases in subjective anxiety despite neural reductions, which the authors suggest may reflect the discomfort of emotional engagement with threat material even as neural markers move toward normalisation. Practical implications emphasized by the investigators include the potential use of circuit-based stratification to identify likely responders for future clinical trials, thereby improving trial efficiency and reducing risks associated with MDMA administration. They note that inclusion of a true baseline visit improved their ability to dissociate drug effects from placebo responses and that adding the 80 mg condition reduced unmasking compared with typical MDMA-assisted therapy trials. Key limitations acknowledged in the extracted text include the small sample size and the need for validation in larger cohorts; the authors recommend further clinical studies to determine whether the acute circuit changes observed translate to therapeutic outcomes when MDMA is paired with structured psychotherapy.