New longitudinal EEG evidence suggests Army Basic Combat Training (BCT) measurably dampens reward processing in the brain, with recruits showing a significant post-training drop in reward-related neural signals. In a 2025 analysis of 123 Army National Guard recruits, time-domain reward positivity (RewP) decreased from pre- to post-BCT (b = −0.67, p < .001), a shift researchers say aligns with the substantial stress burden of a 10-week boot camp environment [1]. The preregistered study is part of the University of Minnesota’s ARMOR project and adds new, quantitative detail to how intensive training may reshape neural responses to gains and losses [2].

The stress signal mattered. Recruits who reported greater perceived BCT stress showed larger reductions in reward-linked brain activity, while those with stronger baseline delta-band reward power reported lower stress during training, a pattern consistent with neurobiological resilience [1]. The authors caution that participants were clinically high-functioning, and the practical, behavioral ramifications of these neural shifts remain to be established with continued follow-up [3].

Methodological nuances temper interpretation. The analysis lacked a non-BCT control group, and the average interval between EEG sessions was close to one year, even though BCT itself lasts 10 weeks; not all time-frequency EEG measures shifted in tandem, underscoring specificity of the effect to the time-domain RewP metric [2]. Still, the combination of preregistration, a longitudinal design, and converging stress associations makes this one of the most rigorous tests of training-related reward signal change to date [5].

Key Takeaways

– Shows time-domain reward processing fell after 10-week BCT in 123 recruits, with a robust RewP decrease (b = −0.67; p < .001) indicating dampened reward sensitivity [1]. - Reveals analytical subsamples of 115–116 for EEG measures and an average inter-visit interval near one year, with no non-BCT control, limiting causal inference [2]. - Demonstrates stress–brain coupling: higher perceived BCT stress predicted larger reductions in reward-related activity; stronger baseline delta-band reward power forecast lower stress [1][5]. - Indicates declines encompassed neural responses to both gains and losses within the RewP window, pointing to a broad attenuation of evaluative reward signaling [1]. - Suggests operational relevance: ARMOR’s 1,201-recruit cohort (launched April 14, 2019) tracks five post-BCT timepoints to inform readiness and resilience interventions [4].

Inside the study of reward processing during boot camp

The findings come from ARMOR, a prospective cohort launched on April 14, 2019, to study 1,201 Army National Guard recruits across multiple timepoints before and after BCT. A 123-person laboratory substudy collected EEG and MRI pre- and post-BCT to identify neurobehavioral markers linked to resilience, readiness, and mental health outcomes in military contexts [4]. This infrastructure enables repeated, mechanistic assessments beyond self-report alone [4].

The reward processing analysis was preregistered and later accepted in Biological Psychiatry: Cognitive Neuroscience and Neuroimaging. The Experts@Minnesota record notes the study’s OSF preregistration and reports the key statistical finding (b = −0.67; p < .001), alongside the prospective result that baseline delta-band reward power predicted lower perceived BCT stress, consistent with a protective neural signature [5]. This transparency supports interpretability and future replication [5].

Although BCT spans 10 weeks, the typical interval between the two EEG lab sessions was approximately one year, reflecting practical scheduling in a real-world military cohort. Analytical sample sizes for core EEG outcomes ranged from 115 to 116 after quality control, and time-frequency EEG measures did not show uniform change, focusing the central conclusion on the time-domain RewP metric [2].

How reward processing changed in the brain

The core result: recruits’ reward positivity, a time-domain event-related potential that indexes rapid neural differentiation of favorable outcomes, significantly decreased from before to after BCT. In model terms, the change was sizable and directionally negative (b = −0.67; p < .001), marking a robust reduction in the brain’s early reward evaluation signal following training [1]. Notably, the attenuation encompassed responses to both gain and loss outcomes within the canonical RewP window [1].

This specificity matters. While the time-domain effect was clear, time–frequency analyses did not move in lockstep, indicating that not all oscillatory markers of reward-related processing followed the same pattern. That divergence helps confine claims to the most reliable metric in this dataset—the RewP—pending replication and finer-grained modeling in future waves [2]. The longitudinal design, however, strengthens the inference that training experiences and the associated stress are linked to the observed neural shift [1].

By concentrating on within-person change, the study reduces confounds that often bedevil cross-sectional comparisons. Even so, the absence of a non-training control group prevents a definitive causal statement that BCT, rather than other intervening factors during the inter-visit interval, is solely responsible for the measured decline in reward processing [2]. The authors explicitly call for controlled designs to settle that question [5].

Stress exposure amplified reward processing dampening

Stress was not just context; it was predictive. Recruits who reported higher perceived BCT stress showed larger decreases in reward-linked neural activity, consistent with a stress-induced blunting of reward responsiveness observed in other high-stress settings. The effect aligns with the notion that intensive training can tax motivational systems, at least transiently, as indexed by EEG [1]. This coupling between subjective stress and neural change provides convergent validity for the central finding [1].

Importantly, baseline delta-band reward power—measured before training—predicted lower self-reported stress across the 10 weeks, suggesting a prospective neural marker of resilience. Individuals with stronger pre-BCT delta-band reward responses appeared less likely to experience high stress during BCT, highlighting a potential biomarker that could inform targeted support or monitoring in future cohorts [5].

What altered reward processing means for readiness and health

Despite the neural decline, recruits remained clinically high-functioning in the period studied, and the authors and outside reporting stress that the downstream behavioral consequences, if any, are not yet known. In practical terms, that means no immediate alarm about day-to-day performance; the key question is whether these neural changes persist and whether they map onto mood, motivation, or decision-making over time [3]. The project’s longitudinal design is specifically aimed at answering those questions [3].

ARMOR’s broader mandate is to identify neurobehavioral signatures that can inform interventions to bolster readiness and mental health. With five post-BCT follow-up timepoints and multimodal assessment, the cohort is positioned to test whether early neural indicators like RewP and delta-band power forecast who thrives under stress—and to guide training supports accordingly [4]. That translational bridge is essential for turning brain metrics into field-relevant insights [4].

Caveats for interpreting reward processing changes

Two cautions loom large. First, without a non-BCT control group, it is impossible to fully disentangle training-specific effects from other life events in the roughly year-long interval between lab visits. Second, not all EEG measures shifted together, arguing against a generalized, global neural dampening and in favor of a more targeted effect on the time-domain reward positivity [2]. These features map the limits of what can be claimed from the present dataset [2].

The authors emphasize that the study was preregistered and call for replication and controlled designs—ideally with randomized elements or matched comparison groups—to validate the magnitude and scope of the observed RewP change. Such designs would help quantify how much of the effect is directly attributable to BCT stress versus other exposures or maturational factors over the interval [5]. That next step is crucial for establishing causality and durability [5].

Finally, the participants remained clinically high-functioning, and public-facing summaries underscore that long-term behavioral or clinical impacts, if any, remain unknown. This is a mechanistic neural finding first; its practical significance will depend on whether it predicts real-world outcomes at upcoming follow-ups [3]. Until then, the message is measured: robust neural change detected, implications pending [3].

The data backbone powering these findings

ARMOR’s scale and design are the engine here. With 1,201 recruits enrolled since April 2019 and repeated assessments spanning five post-BCT timepoints, the project can trace trajectories rather than snapshots. The 123-person lab substudy integrates EEG and MRI around BCT to capture neural and physiological changes with temporal precision—a rare capacity in operational military research [4]. This platform is what makes mechanistic, longitudinal testing of resilience hypotheses feasible [4].

External reporting on Sept. 4, 2025, distilled the message for a wider audience: Army basic training appears to reshape how the brain processes reward, but the recruits remain high-functioning and the behavioral stakes will need future data to define. That balance—between strong neural evidence and appropriately cautious interpretation—frames the next phase of analysis as the ARMOR cohort matures [3].

Sources:

[1] Biological Psychiatry: Cognitive Neuroscience and Neuroimaging (PMC) – Neural Response to Reward and Loss Following Basic Combat Training: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12230802/

[2] PubMed / NCBI – Neural Response to Reward and Loss Following Basic Combat Training (PubMed abstract): https://pubmed.ncbi.nlm.nih.gov/40412619/ [3] PsyPost – Army basic training appears to reshape how the brain processes reward: www.psypost.org/army-basic-training-appears-to-reshape-how-the-brain-processes-reward/” target=”_blank” rel=”nofollow noopener noreferrer”>https://www.psypost.org/army-basic-training-appears-to-reshape-how-the-brain-processes-reward/

[4] University of Minnesota ARMOR Project – About Our Study | The ARMOR Project: https://armor.umn.edu/about-our-study [5] Experts@Minnesota – Neural Response to Reward and Loss Following Basic Combat Training (Experts@Minnesota entry): https://experts.umn.edu/en/publications/neural-response-to-reward-and-loss-following-basic-combat-trainin

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