Abstracts

Rationale:
Memory impairment is a common complaint for people with temporal lobe epilepsy (TLE), however, little is known about the factors that influence memory performance. Moreover, whereas verbal memory is particularly vulnerable in TLE, previous investigation has been confounded by the input modality (auditory versus visual presentation of information). To better understand the cognitive profile of people with TLE, our aims were to (1) compare verbal memory in the auditory (spoken words) versus visual modality (written words), and (2) examine how performance on The Pair Test is influenced by psychological factors.
Method:
Eighteen patients (8 with right-lateralized TLE, RTLE, 10 with left-lateralized TLE, LTLE) and thirty controls were administered the word list learning task from the BIMPB, as well as a novel memory test “The Pair Test”. The Pair Test is a paired associate learning paradigm that provides measures of learning, delayed recall and delayed recognition for verbal information presented in the auditory modality (spoken words), and in the visual modality (written words and written pseudowords). Participants also completed several questionnaires: the HADS (Hospital Anxiety and Depression Scale) for measures of anxiety and depression, the Everyday Memory Questionnaire for a measure of self-reported memory, and the Pittsburgh Sleep Quality Index for a measure of sleep quality. Pearson correlation analyses were computed to (1) compare memory scores for spoken words with memory scores for written words from the Pair Test, and (2) compare memory scores on the Pair Test with scores on the various questionnaires.     Results: (1) A significant correlation was shown people with RTLE between verbal learning scores of the BIMPB and the scores on the spoken words subtests of the Pair Test (R=[ 0.8704],  p=[ 0.0108]), but not with the written words subtests of the Pair Test. This correlation was not significant in people with LTLE or controls. (2) People with TLE and controls all showed significant positive correlations between anxiety scores and recall scores for pseudowords (Controls: R=[0.5505],  p=[0.0119], TLE: R=[0.5350], p=[0.0487]). Measures from sleep and self-reported memory questionnaires were not significantly correlated with memory scores.
Conclusion:
(1) The distinction in the processing of input modality (auditory versus visual modality) in people with RTLE suggests that they may process auditory and visual information differently. Understanding these differences may allow for a more accurate diagnosis of memory impairment, and more importantly, may help target appropriate cognitive rehabilitation. (2) People with and without TLE who demonstrate higher levels of self-reported anxiety showed better ability to recall pseudowords. This suggests the advantage that anxiety grants over more complex tasks which require higher levels of attention (i.e. pseudowords). Together, these findings shed light on the factors that influence memory impairments associated with TLE, and may help the refinement of treatment options.
Funding:
:National Institute for Health Research University College London Hospitals Biomedical Research Center (grant number 229811)