LONDON—Transient epileptic amnesia (TEA) does not appear to increase the risk of Alzheimer’s disease, according to a study presented at the 2017 Alzheimer’s Association International Conference. Persistent memory problems are common in patients with TEA, but the prevalence of dementia in these patients may not exceed that in the general population, the researchers noted.
TEA is a type of adult-onset temporal lobe epilepsy characterized by recurring amnestic seizures. Interictal memory deficits, such as autobiographic amnesia and accelerated long-term forgetting, are common. Short-term follow-up after initiating anticonvulsant medication suggests good seizure control and stable cognition. Recent case reports, however, have raised concerns that TEA may be a prodrome of Alzheimer’s disease.
Investigating Clinical and Cognitive Outcomes
To evaluate the basis for these concerns, Sharon A. Savage, PhD, Lecturer in Aging and Dementia at the University of Exeter Medical School in the United Kingdom, and colleagues investigated clinical and cognitive outcomes of patients with TEA over 10 to 20 years. They also assessed evidence of increased risk of Alzheimer’s disease.
Sharon A. Savage, PhD
The researchers studied two cohorts of patients with TEA. The first cohort included 10 patients followed up at 10 years and 20 years. The second cohort included 42 patients followed up at 10 years. At baseline, both cohorts were compared with age- and IQ-matched healthy controls. Researchers also recorded Alzheimer’s disease diagnoses among participants with TEA and compared the prevalence of Alzheimer’s disease in the study populations with published prevalence rates.
In a subset of patients, Dr. Savage and colleagues assessed cognitive ability using the National Adult Reading Test or the Wechsler Abbreviated Scale of Intelligence. They assessed objective memory using the Logical Memory story 1, Rey Complex Figure, and the Recognition Memory Test. Additional testing examined naming, verbal fluency, and problem solving.
Fifty patients completed neuropsychologic review (mean age at baseline, 66). At last follow-up, clinical information was available for nine patients from Cohort 1 and 37 patients from Cohort 2.
Controls Performed Similarly to TEA Cohorts
At 20 years, no cases of Alzheimer’s disease were reported in Cohort 1. One participant in that group developed vascular dementia, and four died. Four patients in Cohort 2 had Alzheimer’s disease at 10 years, and 15 patients died, including one patient with Alzheimer’s disease.
When TEA data were compared with data from healthy controls, general cognitive ability among patients with TEA was above average with no decline at 10 and 20 years. In addition, significant change from baseline was observed at 10 years for story recall, recognition memory, verbal fluency, and problem solving. Overall, approximately one-third of patients with TEA remained stable or improved on individual test scores at 10 years.
At 20 years, general cognitive ability remained above average for patients with TEA, compared with controls. Performance was not significantly reduced on more than one memory measure per participant.
Researchers concluded that memory problems may continue in TEA despite effective cessation of seizures. Some patients may remain stable over 10 to 20 years, and others may decline. Additional changes in executive function may also develop over time in some patients, the researchers added.
“The prognosis of TEA appears relatively benign,” said Dr. Savage and colleagues. Patients in both TEA cohorts performed similarly to healthy controls on the majority of tests. In addition, life expectancy did not appear to decrease, and seizures were generally well controlled.
—Erica Tricarico