Week 11

Spatial and non-spatial working memory at different stages of Parkinson's disease

Parkinson’s disease (PD) is characterized through the deterioration of motor functions, produced through the decline of dopamine-generating cells. Owen et al. (1997) now suggests that parallel to this motor function degeneration, there is a deterioration of cognitive functions. In their study Owen et al. tested 21 patients with PD in different stages (mild and severe), being either medicated or non-medicated, on their abilities in three different kinds of working memory (spatial, verbal, visual). 


As they predicted, they found an increase of impairment parallel to an increase of severeness in the disease. Non-medicated patients with mild symptoms showed no impairment in all three working memories, medicated patients with mild symptoms showed an impaired spatial working memory but normal abilities for the visual and verbal task, and medicated patients with severe symptoms showed impairment in all 3 tests. It was concluded that first symptoms of PD occur in the frontal lobe (spatial) and then expanding to other brain areas. Compared to Patients with frontal lobe damage however, patients with PD show significantly less severe symptoms.

However, Owen et al. mentioned an extreme difference in task difficulty between the spatial task and the verbal and visual task. A slightly more difficult spatial task would be expected to show impairment even for the first condition. (210 words).

Nevertheless, this study failed to explicitly test any additional frontal lobe functions in PD, which makes it hard to evaluate the expansion of the impairment in these patients. Since frontal lobe patients show a complete destruction of the brain tissue, whereas PD only exhibits deterioration of single areas within the lobe, less severe symptoms might be expectable.