Vulnerability in speed of visuomotor ability.

The aim of this report is to illustrate the utility of neurocognitive testing as an investigative method to establish the presence of persistent effects of concussive brain injury amongst players of a contact sport with high risk of such injury. The report reviews the outcomes of three previously published neuropsychological studies on South African Rugby Union (hereafter 'rugby') from school through to the national adult level. The diagnostic utility of differential effects per se, as well as differential practice effects on visuomotor function, as a means of distinguishing poorer neurocognitive outcome for rugby versus demographically equivalent noncontact sports players, is described. From various methodological angles, at each level of play, the reviewed studies attest to the presence of long-term vulnerability in visuomotor speed in association with participation in rugby, in turn implicating diffuse frontotemporal dysfunction due to repetitive concussive and subconcussive injury amongst rugby players. As visuomotor speed is a prime function called upon for optimal scholastic and occupational performance, the robustly demonstrated decrement is of immediate clinical importance. Of critical heuristic relevance, however, is evidence of residual brain dysfunction in association with rugby as early as school level, which may ultimately be the precursor of chronic traumatic encephalopathy.