Explaining the Objective-Subjective Memory Discrepancy in Epilepsy
MetadataShow full item record
Previous research has shown that epilepsy patients frequently report increased memory impairments compared to the normal population but that their performance on standardised memory tests does not reflect this, displaying an “objective-subjective memory discrepancy” not seen in healthy controls (e.g. Witt et al., 2012). Multiple factors have been proposed to explain this phenomenon, many summarised comprehensively by Hall et al. (2009). These explanations include methodological flaws in both objective and subjective memory assessment as well as potential influences on subjective memory report such as anxiety/depression and illness perceptions. In light of these proposals, this study aimed to assess whether the objective-subjective memory discrepancy remains to be seen in epilepsy patients when they are assessed with an ecologically valid objective memory test, the Rivermead Behavioural Memory Test- Extended Version (RBMT-E) and a comprehensive subjective memory questionnaire, the Prospective Retrospective Memory Questionnaire (PRMQ). Further to this the study aimed to investigate estimated IQ, verbal fluency, longer-term memory failures, anxiety/depression and illness perceptions as potential explanatory factors for the objective-subjective memory discrepancy in epilepsy patients, acting by inflating subjective memory report. Correlational and regression analysis was used to investigate predictors of subjective memory report in patients and this analysis was also performed on control participant data for comparison purposes. This study has found evidence to support an objective-subjective memory discrepancy in epilepsy, with no relationship seen between the two forms of memory assessment, despite worse memory performance in both compared to healthy controls. No evidence was found in support of hypotheses that verbal fluency difficulties may be misreported as subjective memory complaints, therefore influencing the discrepancy, or that objective memory measures are failing to detect memory difficulties in epilepsy patients due to them being too short-term in nature. Subjective memory complaints in epilepsy patients were found to be best predicted in this case by both estimated premorbid IQ and anxiety/depression symptoms, after accounting for IQ effects. This suggests a potential explanatory role for these factors in the objective-subjective memory discrepancy. Lower premorbid IQ and increased anxiety/depression symptoms in epilepsy can be proposed to influence the objective-subjective memory discrepancy seen in epilepsy patients as they inflate subjective memory reports whilst having no effect on objective memory performance. Indications of an influence of illness perceptions in predicting subjective memory complaints, after controlling for effects of IQ and anxiety/depression, were also observed. This finding however was only approaching significance and so the role of illness perceptions in the subjective-objective memory discrepancy in epilepsy therefore warrants future investigation.