Study Identifies Positive Association Between Epilepsy Seizure Severity and Impulsivity

Sang-Ahm Lee, MD, PhD

Data from a recent study suggest a positive, sex-specific association between clinical seizure severity and impulsivity in patients with epilepsy. The findings further suggest that impulsivity could be weakly associated with suicidality in these patients. 

Investigators, led by Sang-Ahm Lee, MD, PhD, department of neurology, Asan Medical Center, University of Ulsan College of Medicine, in Seoul, Republic of Korea, included a total of 146 patients with epilepsy from 6 tertiary hospitals in the multicenter study. Patients had a mean age of 36.9 years (standard deviation [SD], 13.3), and 92 were men (83.0%). The Barratt Impulsiveness Scale Version 11 (BIS-11) was used to measure impulsivity, the Patient Health Questionairre-9 (PHQ-9) to screen for a major depressive episode, the Generalized Anxiety Disorders Scale (GAD-7) to screen for anxiety disorders, and the Mini International Neuropsychiatric Interview (MINI) was used as a diagnostic tool for suicidality. 

Patients had a mean BIS-11 score of 59.3 (SD, 10.7). Investigators identified psychiatric pathologies in several patients, included suicidality, as a PHQ-9 score of 10 or greater was reported for 29 patients (19.9%), a GAD-7 score of 7 or greater for 35 patients (24.0%), and a MINI suicidality score of 6 or greater for 15 patients (10.3%).

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When conducting stepwise linear regression using a coefficient of determination of 0.397, investigators also found that total BIS-11 scores were positively and significantly related to multiple factors, including PHQ-9 scores (P <.001), antiseizure medication (ASM) polytherapy (P <.001), used of lamotrigine (P = .009), and recurrence of generalized or focal to bilateral tonic clonic seizures (GTCS or FBTCS) (P = .010). The recurrence of these seizures was positively associated with BIS-11 scores in men and not women, but the relationship was not statistically significant (F = 3.493; P = 0.065; partial eta² = 0.025).

“We examined association between impulsivity and seizure-related factors in subjects with mixed types of epilepsy. Seizure-related variables such as ASM polytherapy and GTCS or FBTCS recurrence in the last year were positively associated with total impulsivity score and impulsivity subscale scores, as measured by the BIS-11, independent of depressive symptoms,” Lee et al wrote.¹ “Specifically, ASM polytherapy and/or GTCS or FBTCS recurrence, if combined, had stronger associations with total BIS-11 and motor impulsivity scores than depressive symptoms. In contrast, depressive symptoms had stronger associations with attentional and non-planning impulsivity scores than seizure-related variables.”

Both total and subscale BIS-11 scores were higher in participants who had a MINI suicidality score of 6 or greater, when compared with those who had a score lower than 6. After controlling for PHQ-9 scores in a logistic model, positive association of total BIS-11 scores with suicidality score of 6 or greater almost reaching statistical significance (P = .066). 

The study was limited due to its basis as a questionnaire and resultant distrust in memory-based measures. In addition, no evidence for causal or temporal relationships were generated by the cross-sectional design, and analyses were performed using the typical 3-factor model of the BIS-11, which has not been validated for patients with epilepsy. Information about specific medication for the treatment of current psychiatric disorders was not collected, data were susceptible to referral bias, and selection bias was unavoidable. Lastly, 90.4% of patients had an education of 12 or more years, which may limit findings in terms of education. According to investigators, future study will need to assess current findings and develop potential therapeutic interventions to treat impulsivity in this patient population. 

This is not the first study to link suicidality and impulsivity with epilepsy. Last year, a study in Epilepsy & Behavior by Syvertsen et al suggested that trait impulsivity in genetic generalized epilepsy was strongly related to the recent occurrence of myoclonic seizures,² and a 2019 narrative review from Ciuffini et al, published in the Journal of Psychopathology, concluded that there is a dire need for collaborations between physicians treating patients with epilepsy and mental health professionals to provide more comprehensive treatment for those at risk of suicide. “This partnership between neurologists, epilepsy specialists, psychiatrists, as well as other mental health professionals can allow for the development of suicide prevention programs, preventing the loss of life and improving the quality of life,” Ciuffini et al wrote.³

REFERENCES 
1. Lee SA, Choi EJ, Jeon JY, et al. Impulsivity in persons with epilepsy: Association with seizure severity and suicide risk. Published online November 23, 2021. Epilepsy Res. 2021(179):106825. doi:10.1016/j.eplepsyres.2021.106825
2. Syvertsen M, Koht J, Selmar K, et al. Trait impulsivity correlates with active myoclonic seizures in genetic generalized epilepsy. Epilepsy Behav. 2020;112:107260. doi:10.1016/j.yebeh.2020.107260 
3. Ciuffini R, Marrelli A, Perilli E, Stratta P. Epilepsy and suicide: a narrative review. J Psychopathology. 2019;25:155-61.