A biomarker can correlate with recovery without being proven to cause it. That distinction matters in this report of Semax during rehabilitation after ischemic stroke. Primary study
Study outline
The report examined 110 patients divided by early or late rehabilitation, with Semax-treated and untreated subgroups. Plasma BDNF, motor performance, and Barthel scores were assessed. The authors reported higher BDNF and favorable recovery-related findings with Semax, alongside relationships involving rehabilitation timing. Primary report
Our appraisal: two influences require careful separation
Rehabilitation timing and treatment exposure are distinct factors. Patients entering rehabilitation at different stages may differ in recovery potential, initial severity, or other characteristics. A treatment effect cannot be isolated merely by observing that one subgroup improved more.
The indexed abstract does not establish every allocation or masking detail needed to assess bias. It should not be upgraded to a blinded randomized trial without verification. Full-text review must determine how subgroups were formed, whether baseline differences were addressed, and how missing measurements were handled.
The biomarker interpretation requires another boundary. Plasma BDNF is a blood measurement, not a direct measurement of concentration in a particular brain region. A correlation between that blood measure and a functional score does not establish that changing BDNF mediated the functional result.
Functional scales are more clinically relevant than a biomarker alone, but their interpretation still depends on the between-group estimate, uncertainty, and clinical importance of the difference. Statistical association should not replace those details.
This report is relevant human evidence and should be discussed as such, while preserving its unresolved design questions. It does not establish that Semax replaces rehabilitation, proves a BDNF-mediated mechanism, or validates research-market formulations. Its strongest next use is a full-method appraisal of treatment attribution and functional effect size, not an unqualified efficacy claim.
Frequently asked questions
Were human patients included?
Yes, 110 patients after ischemic stroke.
Was rehabilitation timing considered?
Yes.
Was BDNF measured directly in the brain?
The reported measure was plasma BDNF.
Does correlation establish mediation?
No.
Should randomization and blinding be assumed?
No; the full methods must verify them.
Does this show rehabilitation is unnecessary?
No.
What requires closer review?
Group formation, baseline comparability, missing data, and clinically meaningful functional differences.