A pilot study found no significant voxelwise correlation between diffusion measures and symptom improvement across its main correlation analyses. A subsequent responder-group interaction identified a more specific association, which needs to remain separate from a general prediction claim.
Hung and colleagues followed 36 medication-naïve adults with ADHD after clinically selected amphetamine- or methylphenidate-class treatment. Baseline diffusion imaging and executive-function ratings were related to later symptom changes.
Fractional anisotropy describes the directional organization of water diffusion. It is not a direct count of nerve fibers, an assay of amphetamine or proof of how strongly a medicine acted at its molecular target.
Voxelwise correlation analyses did not identify significant relationships across the sample or within responder groups. An interaction analysis found that the relationship between fractional anisotropy and symptom change differed between better and worse responders in a striatal white-matter region.
Follow-up extraction from that region showed an association in better responders. A region selected through an interaction and then examined within subgroups is not equivalent to a prospectively validated whole-sample predictor. Outcome-defined responder groups also require particular care when interpreting prediction.
Treatment was individualized rather than randomized between medication classes, follow-up was limited and the sample was small. The findings cannot establish which medicine a new patient should receive or prove that the identified imaging feature causes response.
This report and clinical-rating predictor research address related questions in medication-naïve adults, so their independence should not be assumed without checking cohort provenance. The useful conclusion is a specific pilot association requiring replication and external validation, rather than a ready-to-use diagnostic or prescribing test.
See another distinction between imaging measures and clinical inference.
Neural and Cognitive Predictors of Stimulant Treatment Efficacy in Medication-Naïve ADHD Adults: A Pilot Diffusion Tensor Imaging Study. doi:10.1177/10870547231222261.