Attentional deficits in Parkinson's disease: partial reversibility with naphtoxazine (SDZ NVI-085), a selective noradrenergic alpha 1 agonist.

Several authors have suggested that catecholamine depletion may affect attentional processes in human subjects and could be implicated in the frontal lobe syndrome that has been described in Parkinson's disease (PD). The present study reports the effects of a placebo and naphtoxazine (SDZ-NVI-085), a selective noradrenergic alpha 1 agonist. These substances were administered to nine parkinsonian patients who were assessed on measures of attention, including neuropsychological tests and evoked potentials. The results indicate that naphtoxazine may improve performance on some tests of "frontal functions," including the Stroop and the Odd-Man-Out tests, which have been previously found to be affected in PD. However, the results of some other neuropsychological tests of frontal function were not affected by naphtoxazine. Specific evoked potentials such as the Nd1 and Nd2 curves--which are thought to reflect attentional processes and which have been found to be affected in PD--were improved by naphtoxazine. Finally, naphtoxazine reduced the percentage of errors and restored the lateralization of N100 during the Shifting Reaction Time Task, suggesting that this substance may act on the processes underlying the shifting deficit in these patients. The results are discussed in terms of the specific cognitive processes that may be affected by naphtoxazine and in terms of the role of the noradrenaline in attentional deficits found in PD.