Problems with the perception of space in Parkinson's disease: a questionnaire study

A questionnaire was completed by 197 putative sufferers from Parkinson’s disease (PD), 43 sufferers from rheumatoid arthritis (RA), and 73 normal age-matched controls. The study built on earlier work to explore further the PD sufferer’s experience of perceptual problems, especially changes in visual perception of the environment. The responses of the RA group allowed investigation of the possibility that any reported problems in the PD group resulted from a chronic and debilitating illness which affects the motor systems, rather than from Parkinson’s disease per se. The control and RA groups differed only on those questions that implicated motor problems (such as reaching for objects). The results suggest that, although the PD respondents are not abnormal in, for example, their descriptions of their own body image or judging the distance between nearby objects, they do notice significant changes in their perception of the world around them, reporting problems with judging distance and motion in the street and problems reaching for objects and moving through narrow spaces within the home. Finally, a factor analysis of the PD responses suggested that they grouped on four main factors, one relating to the motor symptoms of the disease, the second to the perception of peripersonal space, the third to retinal changes, and the fourth to the type of medication. The results of the study suggest visuospatial deficits in PD which may involve the parietal lobe and have implications for understanding the way in which PD patients interact with their environment