Laurie A Miller1, Annu Mothakunnel2, Emma Flanagan3, Armin Nikpour4, Zoe Thayer4. 1. Institute of Clinical Neurosciences, Royal Prince Alfred Hospital, and Central Medical School, University of Sydney, Camperdown, NSW, Australia; ARC-Centre of Excellence in Cognition and Its Disorders, University of Sydney, NSW, Australia. Electronic address: laurie.miller@sydney.edu.au. 2. ARC-Centre of Excellence in Cognition and Its Disorders, University of Sydney, NSW, Australia; Neuroscience Research Australia, Sydney, NSW, Australia. 3. Neuroscience Research Australia, Sydney, NSW, Australia; Norwich Medical School, University of East Anglia, Norwich, United Kingdom. 4. Institute of Clinical Neurosciences, Royal Prince Alfred Hospital, and Central Medical School, University of Sydney, Camperdown, NSW, Australia; ARC-Centre of Excellence in Cognition and Its Disorders, University of Sydney, NSW, Australia.
Abstract
BACKGROUND: Accelerated Long Term Forgetting (ALF) is usually defined as a memory impairment that is seen only at long delays (e.g., after days or weeks) and not at shorter delays (e.g., 30min) typically used in clinical settings. Research indicates that ALF occurs in some patients with epilepsy, but the incidence rates and underlying causes have not been established. In this study, we considered these issues. METHODS: Forty-four patients with a history of focal seizures were tested at 30min and 7day delays for material from the Rey Auditory Verbal Learning Test (RAVLT) and Aggie Figures Test. Recently published norms from a matched group of 60 control subjects (Miller et al., 2015 ) were used to determine whether patients demonstrated ALF, impairment at 30min or intact memory performance. RESULTS: The incidence of ALF in the epilepsy patients (18%) was >3 times higher than normal on the RAVLT, but no different (7%) from the incidence in normal subjects on the Aggie Figures. A different, but again significantly high, proportion of patients (36%) showed shorter-term memory deficits on at least one task. ALF was found mainly in patients with temporal-lobe epilepsy, but also occurred in one patient with an extratemporal seizure focus. Presence of a hippocampal lesion was the main predicting factor of ALF. CONCLUSIONS: Many patients with a focal seizure disorder show memory deficits after longer delays that are not evident on standard assessment. The present study explored the factors associated with this ALF memory profile. These new findings will enhance clinical practice, particularly the management of patients with memory complaints.
BACKGROUND: Accelerated Long Term Forgetting (ALF) is usually defined as a memory impairment that is seen only at long delays (e.g., after days or weeks) and not at shorter delays (e.g., 30min) typically used in clinical settings. Research indicates that ALF occurs in some patients with epilepsy, but the incidence rates and underlying causes have not been established. In this study, we considered these issues. METHODS: Forty-four patients with a history of focal seizures were tested at 30min and 7day delays for material from the Rey Auditory Verbal Learning Test (RAVLT) and Aggie Figures Test. Recently published norms from a matched group of 60 control subjects (Miller et al., 2015 ) were used to determine whether patients demonstrated ALF, impairment at 30min or intact memory performance. RESULTS: The incidence of ALF in the epilepsypatients (18%) was >3 times higher than normal on the RAVLT, but no different (7%) from the incidence in normal subjects on the Aggie Figures. A different, but again significantly high, proportion of patients (36%) showed shorter-term memory deficits on at least one task. ALF was found mainly in patients with temporal-lobe epilepsy, but also occurred in one patient with an extratemporal seizure focus. Presence of a hippocampal lesion was the main predicting factor of ALF. CONCLUSIONS: Many patients with a focal seizure disorder show memory deficits after longer delays that are not evident on standard assessment. The present study explored the factors associated with this ALF memory profile. These new findings will enhance clinical practice, particularly the management of patients with memory complaints.
Authors: Pabitra Hriday Patra; Melissa Barker-Haliski; H Steve White; Benjamin J Whalley; Sarah Glyn; Haramrit Sandhu; Nicholas Jones; Michael Bazelot; Claire M Williams; Alister James McNeish Journal: Epilepsia Date: 2018-12-26 Impact factor: 5.864