Is there a divided attention deficit in patients with early Parkinson's disease?

Divided attention was studied in a group of patients with early Parkinson's disease and compared to normal controls matched for age, gender and intellectual status using a dichotic monitoring task. The Parkinson patients had more difficulty dividing their attention between two competing auditory inputs than the normal subjects. This impairment in divided attention or general attentiveness may be due to changes in the ascending monoamine projections, which have been shown to have a role in auditory attention. A right ear advantage (REA) was also observed. Not only were speech messages discriminated better by the right than the left ear, but these messages were processed more quickly by the right ear.