Background: IVS5-91G>A (rs3812718) polymorphism of the sodium voltage-gated channel alpha subunit 1 (SCN1A) gene has been associated with inadequate responsiveness to common antiepileptic drugs which act as sodium channel blockers. This study was performed to investigate the effect of IVS5-91G>A (rs3812718) polymorphism on lamotrigine (LTG) efficacy in a cohort of patients with non-lesional focal epilepsy taking LTG as monotherapy. Methods: A total of 100 of patients with non-lesional focal epilepsy on LTG monotherapy was included in this prospective interventional study. After reaching a stable dose of LTG patients were followed-up for 12 consecutive months. LTG responsiveness was defined as a 75% or more reduction in seizure frequency on a stable dose of LTG. Genotyping was performed at the end of the study using standard procedures and data were correlated with clinical data. Results: There were no significant differences in the prevalence of responsiveness to LTG between carriers of different genotypes. Average maintenance LTG doses in the responder group differed by genotype in the order AA>GA>GG, but these differences did not reach statistical significance. Conclusion: Our data suggest lack of association between SCN1A IVS5-91G>A (rs3812718) polymorphism and response to LTG.

Background/Objectives: Obstructive sleep apnea (OSA) is a common sleep-related breathing disorder associated with cognitive decline. Evidence regarding the reversibility of these deficits after continuous positive airway pressure (CPAP) therapy remains inconsistent. Methods: This prospective observational study included 60 adults with newly diagnosed moderate-to-severe OSA (median age 51 years; 80% male), who underwent baseline assessment using P300 event-related potentials and the Montreal Cognitive Assessment (MoCA). After three months of CPAP therapy with confirmed good compliance, both measures were re-evaluated. Results: After three months of CPAP therapy, a statistically significant reduction in P300 latency (p < 0.001) and an increase in amplitude were observed, accompanied by significant improvements in executive function (p < 0.001), attention (p < 0.001), and delayed recall (p < 0.001). Conclusions: CPAP therapy leads to measurable recovery of cognitive function in patients with moderate-to-severe OSA, suggesting partial reversibility of neurocognitive impairment associated with sleep-disordered breathing. These findings highlight the importance of early recognition and treatment of OSA to prevent long-term cognitive decline.