The effects of topiramate on cognitive functions of patients with focal epilepsy - a follow-up study in a Serbian sample

Introduction/Objective. The aim of this follow-up study was to determine the effects of topiramate therapy on cognitive functions in patients with pharmacoresistant focal epilepsy. Methods. The study sample comprised of 40 topiramate naive patients. The topiramate starting dose was 25 mg, with a fortnightly titration schedule of 25 mg. A wide range of cognitive functions was evaluated through extensive neuropsychological testing at baseline and six months after reaching the target dose (200 mg/day). Results. The most common side effects following the introduction of topiramate were cognitive impairments, reported by 45% of the participants. The neuropsychological scores on attention, executive function, verbal content recall, improved cognitive flexibility, as well as visuospatial ability and speech, obtained at six-month follow-up were significantly lower than at baseline. However, statistically significant correlation between neuropsychological scores and the number of antiepileptic drugs taken alongside topiramate could not be established. Similarly, no statistically significant differences were noted between the percentage of reduced neuropsychological scores at follow-up pertaining to patients with lower and higher baseline cognitive performance. Moreover, regression analysis indicates that the percentage change in the majority of cognitive scores is unrelated to the age at the epilepsy onset, epilepsy duration, presence of brain pathology on magnetic resonance imaging and percentage change in the depression scale score. Conclusion. Despite slow introduction and administration of a relatively small dose, topiramate exhibits adverse effects on a wide range of cognitive functions, which appear unrelated to the number of additional antiepileptic drugs, baseline cognitive functioning, age at the onset of epilepsy and its duration, presence of brain pathology and the extent of depressive symptoms