A 2025 preprint reported that methamphetamine changed brain-network signatures related to attention and arousal. It is preliminary primary research, and the version discussed here explicitly states that it was not certified by peer review.
Molla and colleagues used a within-subject, placebo-controlled design involving 20 mg methamphetamine in healthy adults. They examined sustained-attention performance and functional connectivity during resting-state and task-based fMRI. Network models addressed attention, arousal and valence.
The paper reported improved attention-task performance and connectivity patterns associated with higher attention and arousal. Valence-network strength was not similarly altered. These selective findings are more specific than a claim that the drug uniformly increased all brain activity.
The preprint’s results also describe an order-dependent accuracy pattern: an advantage appeared among participants receiving methamphetamine after an initial placebo session, while the corresponding comparison was nonsignificant when methamphetamine came first. Placebo-session improvement over orientation also suggested a practice or placebo effect.
Those details limit a simple interpretation of an overall performance advantage. They should remain visible even when the network findings are of interest.
A classifier distinguishing methamphetamine and placebo connectivity patterns within a research dataset does not establish that it can identify intoxication in a new forensic population. Nor is a connectivity score a measured blood concentration or an individual impairment threshold.
Testing robustness across independent samples, doses and contexts is necessary before a research signature can become a reliable diagnostic tool.
This article describes the preprint version, dated May 21, 2025, without treating it as a peer-reviewed final publication. The single-dose design and healthy-volunteer setting also limit generalization. Its value is as preliminary evidence about network sensitivity and a basis for further validation.
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