Planning and realisation of complex intentions in patients with Parkinson’s disease
- 1Department of Gerontopsychology, University of Zurich, Zurich, Switzerland
- 2School of Psychology, University of Aberdeen, Aberdeen, UK
- 3Department of Neurology, University Hospital Charité, Berlin, Germany
- Correspondence to: Dr Matthias Kliegel Institute of Psychology, University of Zürich, Schaffhauserstr 15, CH-8006 Zürich;
- Received 4 August 2004
- Accepted 24 February 2005
- Revised 14 February 2005
Background: There is some evidence that patients with Parkinson’s disease may impaired in prospective memory performance (planning and self initiated realisation of delayed intentions). Little is known about the effect of the disease on distinct phases of prospective memory and the potential mechanisms underlying these effects.
Objective: To investigate intention formation, intention retention, intention initiation, and intention execution of patients with Parkinson’s disease and test for the mediating influence of working memory, inhibition, short term retrospective memory, and divided attention.
Methods: 16 patients with Parkinson’s disease and 16 age and education matched normal controls were given a complex event based prospective memory task which differentiates four phases of prospective remembering. In addition, participants completed tasks assessing potential cognitive mediators.
Results: On the prospective remembering task, Parkinson patients were impaired in the intention formation phase and showed a trend towards impairment in the intention initiation. In contrast, there were no impairments of retrospective intention retention or the fidelity with which the patients executed their previously developed plan. The group effects were related to interindividual differences in working memory span.
Conclusions: The results suggest that the planning phase of prospective remembering is specifically impaired in Parkinson’s disease, and that the impairment is related to working memory deficit. In contrast, even when complex intentions have to be remembered, the retrospective storage of intentions to be performed is not impaired.
↵* To control for medication effects a 12 hour washout phase for antiparkinsonian drugs was chosen. Although this is in line with current standards and comparable studies2324 a longstanding influence of drug treatment cannot be completely ruled out. However, given the increase of motor symptoms associated with an ongoing off-medication phase, longer withdrawal times might not have been tolerable for patients and it was assumed they would substantially reduce the patients’ compliance.
† We decided to apply analysis of covariance (ANCOVA) in order to address directly the issue of potential mediators for obtained group differences in the ANOVAs. Using simple correlation analyses, partial correlations, or multiple regression analyses, respectively, as done in previous work22 did not change the results.
Competing interests: none declared