Interictal epileptiform discharges were associated with poorer cognitive performance in adult epileptic patients

•Poorer cognitive performance in ACER was found in adult patients with IEDs.•Verbal Fluency and Language scores were mainly associated with the low scores.•Sleep phase IEDs were related to the poorer cognitive performance in ACER as well.

ObjectiveCognitive impairment is one of the major consequences of epilepsy and has been shown to reduce quality of life. Interictal epileptiform discharges (IEDs) were associated with poorer cognitive performance in children, and the aim of this study was to determine whether there was a similar association in adults.MethodsA prospective cohort of 167 seizure-free adult patients underwent EEG recording and extensive cognitive evaluations. Global cognition was evaluated using Addenbrooke's Cognitive Examination-Revised (ACE-R), while sub-dimensions of cognition were evaluated using the Auditory Verbal Learning Test (AVLT), Trial Making Test (TMT)-A and -B, and the 5 constitutive subscales of ACE-R.ResultsPerformance in ACER, but not AVLT or TMT, was significantly lower in patients with general IEDs. Furthermore, the five subscale scores of ACE-R were significantly lower in patients with general IEDs, and verbal fluency and language scores contributed in a major way to the low scores. Stratified analysis showed that sleep-phase IEDs were also associated with lower performance in ACE-R and its subscales. Finally, non-rapid eye movement (NREM)-IEDs were found to be associated with visuospatial and memory impairment, and IEDs while awake, with poorer performance in TMT-B.SignificanceThe results of this study demonstrate that cognitive performance is associated with IEDs in adult epilepsy patients, and could serve as a springboard for further research into reducing IEDs to bring about better cognitive performance.