Resting motor threshold is the minimum intensity that evoked a visible contralateral involuntary finger twitch.
Resting motor threshold asymmetry is the absolute difference between the left and right RMT measurements.
Conflicting results have emerged from studies examining the potential of resting motor threshold as a neurophysiological marker for Alzheimer's disease diagnosis and progression.
In this study, the authors estimated the strength of the association between Resting motor threshold measurements and severity of cognitive impairment in a relatively large sample of clinical trial participants with mild to moderate Alzheimer's disease.
Resting motor threshold for each participant was determined by applying single-pulse transcranial magnetic stimulation repeated at varying intensities over left and right sides of the primary motor cortex.
Cognitive impairment was measured with the Montreal Cognitive Assessment and the Alzheimer Disease Assessment Scale - Cognitive scores.
Although the left and right resting motor threshold was lower in CDR 2 than in CDR 1 participants, neither RMT nor RMT asymmetry correlated significantly with cognitive test scores.
In conclusion, authors' study in a large sample size does not support the idea that resting motor threshold is a sensitive marker of cognitive decline/severity in Alzheimer's disease.