Psychogenic non-epileptic (functional) seizures in adults with intellectual disability and epilepsy: A matched case-control study.

Abstract

To describe the characteristics of psychogenic non-epileptic (functional) seizures (PNES) in adults with epilepsy and intellectual disability (ID) and to establish differences and risk factors regarding psychosocial functioning between individuals with and without PNES. Adults with ID and epilepsy living in epilepsy care facilities in The Netherlands were screened for PNES by a neurologist. A control group consisting of people with epilepsy and ID, without PNES, was matched according to age, sex, and level of ID. Objective data were retrieved retrospectively from clinical notes of the resident. Standardized questionnaires and tests, adjusted for people with ID, were obtained from participants and their nursing staff. Differences were analyzed using paired t tests, Wilcoxon signed-rank tests, or McNemar's tests, appropriate for matched case-control studies. Conditional logistic regression identified PNES risk factors. Five hundred forty individuals were screened, of which 42 had PNES (point prevalence 7.8%). In total, 35 cases and 35 controls gave consent. Proxy reports indicated that PNES impacted daily life in 79% by adjusting the individual's schedule, and caused minor injuries in one-third. Those with PNES were mainly female (69%); had a mild (46%) or moderate (37%) level of ID; showed more symptoms of depression (p = .024), anxiety (p = .030), self-injurious behavior (p = .015); and experienced more negative life events (p < .001). Clinically relevant predictors of PNES were the number of negative life events (odds ratio [OR] 1.71, 95% confidence interval [CI] 1.12-2.53) and self-injurious behaviors (OR 5.27, 95% CI .97-28.81). Previously, PNES in individuals with ID and epilepsy were described mainly as a reinforced behavioral pattern, due to limited associations with psychiatric disorders. Our results demonstrate that this population does show individual psychosocial vulnerabilities when measured with instruments adjusted for this population, as indicated by proxy reports from daily caregivers. Viewing PNES as an involuntary response, especially for stress-prone individuals with ID, could reduce stigma and improve treatment.