INVESTIGATING THE PROGNOSIS OF TRANSIENT EPILEPTIC AMNESIA: DOES IT LEAD TO ALZHEIMER’S DISEASE?

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Transient Epileptic Amnesia (TEA) is a form of temporal lobe epilepsy characterised by seizure-induced amnesia, often accompanied by ongoing memory disturbances of autobiographical amnesia and accelerated long-term forgetting. Short-term follow-up, 1–2 years after commencing anticonvulsant therapy, suggests a relatively stable cognitive profile. Recent case reports, however, have raised concerns regarding a risk of developing Alzheimer's Disease (AD). This paper reports on the clinical and cognitive outcome of TEA patients over a 10 to 20-year period. Two cohorts of TEA participants were studied at 10-year intervals: an initial cohort of 10 patients (C1), followed up at 10 and 20- years; and an additional 42 patients (C2), followed up at 10 years only. Information regarding clinical outcomes was gained via GP records and clinical interview. Objective memory function was determined at each time point via comprehensive neuropsychological assessment, where possible. Patients were compared with age-matched healthy control participants. Clinical information was available for 9 patients from C1 (90%), and 37 (88%) from C2. In C1, there was no indication of AD in the 4 participants (40%) who had died (mean age at death = 82 years). One participant was diagnosed with Vascular Dementia. In C2, 15 participants (40%) had died, including one patient with AD (mean age of death = 81 years). Dementia was diagnosed in a further 5 patients (3 with AD). Subjective memory complaints were significantly greater in TEA patients than matched controls, although some reported no concerns or stable memory difficulties. Neuropsychological assessment showed no evidence of a general cognitive decline, with TEA participants performing similarly to healthy controls on the majority of tests. Within the memory domain, both TEA cohorts included patients with stable memory performance over time relative to healthy controls, as well as patients showing impairments on one or more memory measures. Additional impairments in other cognitive domains (typically executive function) were observed in some patients. Despite concerns raised regarding dementia, the prognosis of TEA appears relatively benign over the long term. While persistent memory difficulties are common, the prevalence of dementia in TEA does not exceed population prevalence data.