Measurement and interpretation
Definition
Target engagement is evidence that an intervention produced the predicted measurable effect on its hypothesised biological or behavioural target.
Aliases and abbreviations
mechanistic target engagement · engagement of the target
Editorial record
Published: August 25, 2026 · Reviewed: August 25, 2026
Expanded definition
A target may be molecular, cellular, circuit-level, physiological, behavioural, or another clearly defined mechanism. The measure used should be objective, reproducible, and linked to a pre-specified hypothesis.
Demonstrating target engagement is different from showing clinical benefit. Researchers may first ask whether the target changed and then test whether that change is associated with the outcome of interest.
In VNS research, electrical output, skin sensation, electrode contact, or a change in one physiological measure does not automatically establish selective engagement of a vagal pathway. The inference depends on the measure and study design.
What the term does not establish
Why the distinction matters
Separating mechanism evidence from outcome evidence makes negative, mixed, and positive studies more informative and reduces overclaiming.
Main guide
A map of mechanisms, outcomes, device differences, and interpretation boundaries across VNS methods.
Explore mechanism researchSources and further reading
Related terms
Safety and research
Protocol and stimulation parameters
Measurement and interpretation
Safety and research
Measurement and interpretation
Stimulation methods
Editorial scope
This glossary entry supports general education. It does not diagnose, recommend treatment, or transfer findings from one VNS method, protocol, or device to another.