Suicidality at Epilepsy Diagnosis and Future Treatment Resistance in Adults With Focal Epilepsy

Importance: Psychiatric disturbances are common in epilepsy and are associated with increased risk of premature mortality, lower quality of life, and poor response to antiseizure medications (ASMs). Objective: To evaluate the role of psychiatric disturbances at the time of epilepsy diagnosis in predicting risk of future treatment resistance in focal epilepsy. Design, Setting, and Participants: The Human Epilepsy Project (HEP) is a prospective, observational, international, and multicenter cohort study with follow-up for up to 6 years. Participants with newly diagnosed focal epilepsy, enrolled within 4 months of initiating ASM treatment, between the ages 18 and 60 years, and without significant other comorbidities were recruited during the open period of 2012 to 2020. Data analysis was performed from January to September 2025. Exposure: Presence of a psychiatric diagnosis. Main Outcomes and Measures: Presence of psychiatric diagnosis (mood/anxiety disorders) measured by Mini International Neuropsychiatric Interview (MINI) and/or suicidality measured by Columbia-Suicide Severity Rating Scale (C-SSRS) at enrollment. Treatment response included the following outcomes: treatment resistant (TR), defined as failure of first 2 adequate ASM trials (ongoing seizures at/above therapeutic doses); treatment sensitive (TS), defined by a minimum period of seizure freedom on first 2 adequate ASM trials (12 months/3-fold greatest pretreatment seizure-free interval, whichever is longer); and indeterminate (neither TR/TS). Results: Of 376 enrolled adults, 347 (median [IQR] age at seizure onset, 33 [23-44] years; 209 female [60.2%]) completed the MINI and C-SSRS at enrollment. Of these individuals, 191 (55%) were TS, 83 (24%) TR, and 73 (21%) indeterminate. The rate of psychiatric disturbance (mood/anxiety disorder; suicidality) at epilepsy diagnosis was 38% (n = 133). Fifty-seven (16%) had mood/anxiety disorder(s) without suicidality, and 75 (22%) expressed suicidality with or without a psychiatric disorder. Suicidality at epilepsy diagnosis was associated with greater than 2-fold risk of developing TR (relative risk [RR], 2.02; 95% CI, 1.32-3.09; P = .001). There were no significant overall associations between mood/anxiety disorders and TR. Suicidality alone significantly increased TR probability from 16.3% (95% CI, 11.3%-21.3%) in those with no psychiatric disturbance to 47.1% (RR, 2.89; 95% CI, 1.65-5.05; P < .001). Anxiety disorder alone increased TR probability to 32.9% (RR, 2.02; 95% CI, 1.10-3.71; P = .02), although this was not statistically significant after correcting for multiple comparisons. There was no significant change in TR probability when mood disorder alone was present; however, presence of mood disorder with suicidality increased TR probability to 39.6% (RR, 2.43; 95% CI, 1.26-4.68; P = .008). Conclusions and Relevance: Results of this cohort study reveal that suicidality at the time of focal epilepsy diagnosis was associated with future drug resistance and may be a marker of more severe neuropathology. Psychiatric screening at time of diagnosis may facilitate early identification of patients at risk for treatment refractory epilepsy syndromes.