To identify differences in memory among patients with epileptic or psychogenic seizures compared with healthy controls.

Patients with epilepsy report that difficulty remembering impacts everyday life, causing significant distress.  Studies have shown that short-term memory may not be impaired and that long-term memory degrades at a significantly higher rate.  This phenomenon has been termed accelerated long-term forgetting.   

Patients with seizures were admitted to the Dartmouth-Hitchcock Medical Center for video-EEG monitoring.  Patients and healthy controls were asked to watch a 30-minute nature film.  (Only patient EEG data were collected and synced with the film in 1 second intervals.)  All participants were then asked to answer questions about the film at two time points: (1) immediately after watching, and (2) 24 hours after watching.  Participants could to provide their own response (free recall) or, if unsure, were prompted to choose the correct answer on the next screen (recognition).  They then rated their confidence level in their chosen answer.  Each participant received three questions per scene of the film targeting a distinct type of memory: verbal, episodic, and visual.  After discharge, patients’ seizures were characterized as epileptic or psychogenic using EEG data.

Same-day recall is impaired in patients with epileptic and psychogenic seizures compared to controls.  Those with epileptic seizures have a decreased confidence rating [Likert score], likely because of the stigma associated with their disorder.

24-hour recall is impaired in patients with epileptic seizures, which demonstrates accelerated long-term forgetting.  There is no difference in the 24-hour recall of patients with psychogenic seizures and controls.

Our results indicate impairments in same-day and 24-hour tests of memory in patients with epilepsy.  Patients seem acutely aware of their poor performance, as they consistently rate their confidence lower than controls.  These results suggest that epileptic seizures alter cognition in a way that psychogenic seizures do not.