Abstract
Parkinson’s disease (PD) is the second most common neurodegenerative disease in the world. Recently, cognitive dysfunction has started to be viewed as a core symptom of PD, resulting in the proliferation of numerous studies assessing cognitive deficits specific to PD patients. There are, however, some issues with the methods employed in these studies. Supplementary factors such as age, gender, handedness, education and time of testing have been shown to affect performance on cognitive tasks in previous research. However, in cognitive PD research, these factors are often counterbalanced and left out of analysis or ignored completely, meaning their effects could be overlooked. The current study aimed to address this issue by identifying which of these factors (if any) affect performance on a range of cognitive tasks, and whether their influences interact with PD. 47 PD patients and 27 healthy controls matched for age, gender, education, handedness and time of testing were assessed using standard validated clinical inventories and a computerised cognitive battery. General linear models were then produced to determine which supplementary factors affected performance on the cognitive tasks and to identify any interaction effects. Results showed that age, education and time of testing affected performance on at least one of the tasks used in the current study, but these observations should be interpreted tentatively as the current study was not without limitations. Solutions to these limitations, implications of the findings and future directions of study are then discussed.