Accelerated long-term forgetting in children with temporal lobe epilepsy.
Adults with temporal lobe epilepsy (TLE) have been found to have accelerated long-term forgetting, but this phenomenon has not yet been investigated in children. Although deficits in recall of materials after short (20- to 30-minute) delays have been shown to slowly emerge from childhood to adolescence in patients with TLE, it is unknown whether such a trend will also be found in recall of materials after long delays. This study examined the presence of accelerated long-term forgetting in children with TLE and how it relates to chronological age. Twenty-three children with TLE and 58 healthy controls of similar age, sex distribution and socioeconomic status completed a battery of neuropsychological tests, including standardised tests of story recall and design location, as well as two experimental tests requiring the learning of words and design locations to a criterion, both of which assessed recall after short (30-min) and long (7-day) delays. Word recall at the 7-day delay (relative to the 30-min recall) was significantly poorer in the TLE group, compared to the control group. The TLE group also exhibited worse 30-min recall performance on a standardised test of story recall. Individual patient analyses revealed dissociation between performance on the experimental and standardised verbal memory tests; children who were impaired on the experimental test (7-day delay) were not impaired on the standardised test (30-min delay). Compared to controls, patients with a left-hemisphere seizure focus recalled fewer words at short and long delays while patients with an abnormal hippocampus recalled fewer words at the long delay. No between-group differences were found with respect to the design location task. Age negatively correlated with the recall of words after short- and long-term delays within the TLE group, where older age was associated with worse memory. This association was not present in the control group. To our knowledge, this is the first study to show evidence of accelerated long-term forgetting in children with TLE, which could not be explained by poor performance on standardised memory tests. Additionally, these results suggest that the developmental trajectory of long-term memory in children with TLE is similar to that of short-term memory: deficits emerge gradually, therefore older children are more likely to present with long-term memory deficits.
School of Psychology, The University of Sydney, Australia.
Michael B
MB
Gascoigne
The University of Toronto and The Hospital for Sick Children, Toronto, Canada.
Mary Lou
ML
Smith
Children׳s Hospital Education Research Institute, The Children׳s Hospital at Westmead and Discipline of Paediatrics and Child Health, Faculty of Medicine, University of Sydney, Australia.
Belinda
B
Barton
T.Y. Nelson Department of Neurology and Neurosurgery, The Children׳s Hospital at Westmead, Sydney, Australia.
Richard
R
Webster
T.Y. Nelson Department of Neurology and Neurosurgery, The Children׳s Hospital at Westmead, Sydney, Australia.
Deepak
D
Gill
School of Psychology, The University of Sydney, Australia; ARC Centre of Excellence in Cognition and its Disorders, Australia. Electronic address: suncica.lah@sydney.edu.au.
Suncica
S
Lah
D000293:Adolescent; D000367:Age Factors; D002648:Child; D004833:Epilepsy, Temporal Lobe / Q000150:complications*; D005260:Female; D006801:Humans; D008297:Male; D008569:Memory Disorders / Q000150:complications*; D057567:Memory, Long-Term; D008570:Memory, Short-Term; D011939:Mental Recall; D013067:Speech Perception
Accelerated forgetting; Consolidation; Memory; Recall; Temporal lobe epilepsy