Clarifying the Nature and Extent of Prospective Memory Impairment after Stroke

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Shum, David

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Cornwell, Petrea

Fleming, Jennifer

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Prospective Memory (PM) is needed and used when intentions are to be carried out in the future and impairments in this type of memory can have detrimental effects on individuals and their ability to live independently. Little research has been conducted to examine if PM is impaired after stroke, the underlying reason(s) for impairment, and whether PM can be improved after a stroke. Therefore, the present thesis aimed to clarify the nature and extent of PM impairment after stroke. Twenty-eight individuals with stroke, 25 of their significant-others, and 27 neurologically healthy controls took part in the study. For the purposes of data analysis and ease of interpretation, the larger overall study has been broken into three studies outlined in this thesis. Study 1 aimed to compare self-reported PM of individuals with stroke to neurologically healthy controls and their significant-others to determine if perception of PM ability is impaired after stroke. Individuals with stroke reported significantly more Basic Activities of Daily Living (BADL) PM failures compared to controls on part A of the Brief Assessment of Prospective Memory (BAPM). However, on part B, individuals with stroke reported BADL PM failures to be less problematic or important compared to controls, suggesting a lack of awareness into the consequences of PM failure. Individuals with stroke reported more PM and Retrospective Memory (RM) failures than controls on the Prospective and Retrospective Memory Questionnaire (PRMQ). On average, the significant-others rated more frequent memory failures for individuals with stroke than the individuals themselves on the BAPM and PRMQ, however, these differences were not statistically significant. Results of the study clarified the results of previous research and highlighted that individuals with stroke report more PM failures than controls but underestimate the importance of these PM failures. These findings have implications for PM impairments and treatment in this clinical population. Study 2 compared the PM performance of individuals with stroke and controls on a standardised measure, the Cambridge Prospective Memory Test (CAMPROMPT), to determine if PM is impaired after stroke. In addition, it aimed to explore underlying reason(s) for PM impairment by examining the relationships between demographic, cognitive, and metacognitive variables and PM performance. Results showed that individuals with stroke performed more poorly on both event- and time-based PM compared to controls, suggesting PM impairment. In addition, when placed in age and estimated IQ adjusted normative categories based on their PM scores, 39.2% of individuals with stroke were considered to have PM impairment to some extent. No significant differences were found between event- and time-based PM performance for individuals with stroke, suggesting similar level of impairments for both types of PM. After controlling for group membership, event-based PM was found to be significantly predicted by the demographic variable of age, and the cognitive variables of RM retention and global cognitive function. Time-based PM was found to be significantly predicted by the demographic variable of age and the metacognitive variable of note-taking. These findings did not align with previous research that found that cognitive/executive function was more predictive of time-based than event-based PM. While limitations exist in the current research, the findings have helped to confirm that PM impairment does exist after stroke, especially when using standardised clinical PM measures. Furthermore, PM impairment may be predicted by variables such as older age, lack of strategy use, RM, and poorer executive function ability. Study 3 aimed to examine reasons for possible PM impairment after stroke by manipulating cue focality and implementation intentions. Additionally, it aimed to assess the use of virtual reality in the assessment of PM. Firstly, both groups rated the Virtual Reality Prospective Memory Shopping Task (VRPMST) favourably when compared to an experimental measure of PM (Lexical Decision Prospective Memory Task; LDPMT), particularly in terms of similarity with everyday life, suggesting high ecological validity of the VRPMST. On the VRPMST, PM results were similar to the CAMPROMPT, LDPMT, and Delayed Message Task (DMT), specifically for time-based PM. This suggests that the VRPMST is useful in the assessment of time-based PM both in neurologically healthy controls and individuals with stroke. A main effect of focality was found for performance on event-based PM, with focal cues being higher than non-focal cues, however, significant differences were only found for the control group. This suggests that individuals with stroke showed similar level of impairments in event-based PM when both focal and non-focal cues were used. Implementation intentions were found to significantly improve event-based PM in individuals with stroke (on the LDPMT) and improve time-based PM so that individuals with stroke were performing similarly to controls (on the LDPMT, VRPMST, and DMT). The study helped to confirm findings of previous literature that PM impairments exist after stroke, particularly for time-based PM, and may be due to impairments in both spontaneous retrieval and strategic monitoring strategies after stroke. Overall the findings of this thesis indicate that PM is impaired after stroke, particularly for time-based PM, and that some improvements in PM performance can be made with simple rehabilitative techniques like implementation intentions. In addition, possible reasons for PM impairment after stroke have been identified including: deficits in both spontaneous and strategic monitoring processes; advanced age; and both cognitive function and RM impairment. Moreover, the findings of this study may help provide further understanding of the theoretical models of PM (particularly in terms of PM cue types and monitoring strategies) and inform clinical/rehabilitative practices in how to assess and improve PM after stroke. Future research is recommended with larger sample sizes to examine additional factors that could impact PM after stroke (i.e., time-post stroke, stroke location/severity). Implementation intentions only target one phase of the PM process; therefore, it is recommended that future research develop rehabilitative techniques targeted at other stages of PM to see if PM can be improved even more.

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Thesis (PhD Doctorate)

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Doctor of Philosophy (PhD)


School of Applied Psychology

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Prospective memory


Implementation intentions

Monitoring processes

Theoretical models

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