METAANALYTIC COMPARISON OF THE COMPONENTS OF VISUAL COGNITION IN PARKINSONS-DISEASE

Controversy surrounds the presence of deficits of visual cognition in Parkinson's Disease. This literature has been seriously undermined by a number of methodological and theoretical faults that make interpreta tion of this hypothesis difficult. This review proposes a structure of visual cognition composed of 13 aspects. A meta-analysis of these com ponents on 70 studies that used standardised neuropsychological tests and an appropriate normal control group indicates that the PD subjects are significantly compromised on tests of attention and concentration , complex visuospatial functions, and multifactorial spatial functions . More detailed analysis of the basic components of visual cognition w as not undertaken due to low statistical power; hence, it remains uncl ear whether these subjects have primary visual processing deficits in association with their higher order deficits. The observed deficits ma y be interpreted as being a consequence of either undetermined lower l evel visual cognitive deficits or a compromise in executive functionin g.