Attentional and perceptual impairments in Parkinson's disease with visual hallucinations.

Visual hallucinations (VH) are common in Parkinson's Disease (PD). Both deficits of perception and attention seem to play a role in the pathogenesis of VH in PD. However, the possible coexistence of impairments in attention and visual perception in PD with VH is not known. This study investigated both attention and visual perception in non-demented PD patients with VH, compared to PD patients without VH and healthy controls. Fourteen participants were included in each group. All patients were assessed with sustained visual attention and object and space perception tests. Only PD patients with VH showed impairments on object and space perception. In addition, PD patients with and without VH showed impairments on sustained visual attention, being more severely affected in PD patients with VH. Only in PD patients with VH sustained visual attention was associated with a decreased object and space perception. The results of our study thus suggest that in PD patients with VH an impairment of object and space perception, possibly in association with a decreased sustained visual attention, might play a role in the pathogenesis of VH.