The BRadykinesia Akinesia INcoordination (BRAIN) Tap Test: Capturing the Sequence Effect.

Background: The BRadykinesia Akinesia INcoordination (BRAIN) tap test is an online keyboard tapping task that has been previously validated to assess upper limb motor function in Parkinson's disease (PD).

Objectives: To develop a new parameter that detects a sequence effect and to reliably distinguish between PD patients and medication. In addition, we sought to validate a mobile version of the test for use on smartphones and tablet devices.

Methods: The BRAIN test scores in 61 patients with PD and 93 healthy controls were compared. A range of established parameters captured number and accuracy of alternate taps. The new velocity score recorded the intertap speed. Decrement in the velocity score was used as a marker for the sequence effect. In the validation phase, 19 PD patients and 19 controls were tested using different hardware including mobile devices.

Results: Quantified slopes from the velocity score demonstrated bradykinesia (sequence effect) in PD patients (slope cut-off -0.002) with 58% sensitivity and 81% specificity (discovery phase of the study) and 65% sensitivity and 88% specificity (validation phase). All BRAIN test parameters differentiated between and medication states in PD. Differentiation between PD patients and controls was possible on all hardware versions of the test.

Conclusion: The BRAIN tap test is a simple, user-friendly, and free-to-use tool for the assessment of upper limb motor dysfunction in PD, which now includes a measure of bradykinesia.