Slowing with end-stage renal disease: Attentive but unprepared to act

Dialyzed patients show longer response latencies to stimuli than healthy controls. This study was designed to learn if this abnormal latency may be related to an impairment in the networks that mediate the allocation of sensory-attention (inducing a delay in stimulus recognition-awareness) and/or an impairment of intentional motor preparation (inducing a delay in action-initiation). Dialyzed patients with end-stage renal disease and matched healthy controls were assessed using reaction time tasks from the ROtman-Baycrest Battery to Investigate Attention (ROBBIA) and event-related potentials (ERPs) to help elucidate the possible attentional and/or intentional brain mechanisms that may account for this slowing. The following ERP components were analyzed for single attentional and intentional processes: response preparation (Contingent Negative Variation); perceptual preparation (P1); selective attention and monitoring (P300/Late Positive Potential). Patients (vs. controls) had a decreased ability to sustain response preparation under the condition of a long (3 s) but not a short (1 s) preparation period. This action-intentional deficit was, however, not accompanied by impaired perceptual preparation and monitoring. Future research may investigate whether deficits observed in dialyzed patients can be reduced with treatments such as kidney transplantation.