Visual perception in Parkinson disease dementia and dementia with Lewy bodies

Abstract

Abstract-Objective:To quantify visual discrimination, space-motion, and object-form perception in patients with Parkinson disease dementia (PDD), dementia with Lewy bodies (DLB), and Alzheimer disease (AD). Methods: The authors used a cross-sectional study to compare three demented groups matched for overall dementia severity (PDD: n ϭ 24; DLB: n ϭ 20; AD: n ϭ 23) and two age-, sex-, and education-matched control groups (PD: n ϭ 24, normal controls [NC]: n ϭ 25). Results: Visual perception was globally more impaired in PDD than in nondemented controls (NC, PD), but was not different from DLB. Compared to AD, PDD patients tended to perform worse in all perceptual scores. Visual perception of patients with PDD/DLB and visual hallucinations was significantly worse than in patients without hallucinations. Conclusions: Parkinson disease dementia (PDD) is associated with profound visuoperceptual impairments similar to dementia with Lewy bodies (DLB) but different from Alzheimer disease. These findings are consistent with previous neuroimaging studies reporting hypoactivity in cortical areas involved in visual processing in PDD and DLB. NEUROLOGY 2004;63:2091-2096 Parkinson disease (PD) is associated with a higher risk of developing dementia compared to healthy elderly controls; longitudinal studies suggest that up to 78% of PD patients will develop dementia after nearly two decades of motor symptoms.1 Once dementia is established, clinical symptoms of PD dementia (PDD) may show, apart from a longer duration of motor features, considerable overlap with dementia with Lewy bodies (DLB). The postural instability-gait type of parkinsonism is overrepresented in PDD and DLB 2 and both disorders show similar fluctuation of attention 3 and response to cholinergic therapy. 4,5 Studies comparing visual perception and visual construction of PDD with Alzheimer disease (AD) have revealed contradictory results. Some studies report PDD to be more impaired, 6,7 whereas other studies found no differences. 8,9 Similar inconsistencies have been found when perception of PD patients was compared with healthy controls.10 Since operationalized criteria to define the clinical boundaries between PD and PDD or PDD and DLB require refinement, these inconsistencies may be partly due to diagnostic heterogeneity. When DLB was compared with AD, studies consistently reported greater visual impairment in DLB 11 and a recent study found similar impairments in pentagon copying in DLB and PDD.12 Some of these studies used construction tasks as evidence, but this may not be legitimate given the motor impairments in these patients. Studies quantifying visual perception of DLB and PDD using tasks without motor requirements are lacking.Peripheral structures such as the retina, the optic nerve and tract, and primary visual cortex are multimodal in their function, whereas the visual association cortex is more specialized.13 Low-level visual discrimination is mainly processed in visual area V1/ V2, whereas high-level visual functions require additional activati...

Paired Studies Comparing Clinical Profiles of Lewy Body Dementia with Alzheimer’s and Parkinson’s Diseases

“…The prominent non-dominant hand 9HP score differences between LBD and PD subjects likely reflect the more impaired visuospatial impairments seen in our LBD group [48].…”

Dementia Associated with Parkinsons Disease

“…10 Visual-spatial abstraction and reasoning were more impaired in patients with PD-D, whereas visual-spatial memory tasks were worse in patients with AD. This was especially evident in more complex tasks that required planning and sequencing.…”

Dopaminergic contributions to distance estimation in Parkinson's disease: A sensory-perceptual deficit?

“…Evidence of a visual processing deficit resulting from impairment of the magnocellular system (i.e., an area in the brain that processes visual information about movement) has been hypothesized (Castelo-Branco et al, 2009;Silva et al, 2005), since peripheral vision is known to be altered in PD by an abnormality of dopaminergic amacrine cells (Bodis-Wollner & Paulus, 1999). There has been some support for this hypothesis since studies have shown that those with PD have difficulty identifying the direction or speed of movement when solely relying on moving visual stimuli in their periphery (Mosimann et al, 2004;Trick, Kaskie, & Steinman, 1994) . However, research investigating motion discrimination in PD did not find that the damaged magnocellular pathway was predictive of motion integration deficits (Castelo-Branco et al, 2009).…”