Premature mortality in persons with epilepsy and schizophrenia: A population-based nationwide cohort study

Febrile seizures and childhood epilepsy and risk of internalizing and psychotic symptoms

OBJECTIVE

To assess whether children with febrile seizures and/or epilepsy were at increased risk of experiencing internalizing symptoms or psychotic-like experiences at age 11 years.

METHODS

This cohort study includes 44 819 children from the 11-year follow up of the Danish National Birth Cohort. Information on childhood seizures was retrieved from the Danish National Patient Registry, whereas child psychiatric symptoms were assessed in a web-based questionnaire using the Adolescent Psychotic-like Symptom Screener and the Strength and Difficulties Questionnaire. Adjusted odds ratios (aORs) with corresponding 95% confidence intervals (CIs) for the association between childhood seizures and internalizing symptoms (symptom score ≥8) and psychotic-like experiences (≥2 definite experiences) were obtained using logistic regression models.

RESULTS

A total of 1620 children with febrile seizures (3.6%), and 311 children with epilepsy (0.7%) were identified. When adjusted for potential confounders, no association between febrile seizures and psychiatric symptoms was observed, and no association was observed between epilepsy and psychotic-like experiences. However, the OR for internalizing symptoms was 1.76 (95% CI: 1.20-2.58) in children with epilepsy compared to children without. This higher risk was evident mainly in boys (OR 2.30, 95% CI 1.37-3.85), children with ≥2 epilepsy-related hospital admissions (OR 2.79, 95% CI 1.81-4.32), and children whose age at first epilepsy-related hospital admission was 0-3 years (OR 2.47, 95% CI 1.45-4.19).

SIGNIFICANCE

No association was found between febrile seizures and psychiatric symptoms or epilepsy and psychotic-like experiences at age 11. However, boys with epilepsy were at higher risk of experiencing internalizing symptoms.

Epilepsy and psychiatric comorbidities: A bidirectional mendelian randomization study

STUDY OBJECTIVES

Psychiatric comorbidities are relatively common among patients with epilepsy; however, the underlying mechanisms of this association remain largely unknown. The objective of this Mendelian randomization (MR) study was to analyze the genetic correlations and causality underlying these reciprocal associations.

METHODS

Single-nucleotide polymorphisms associated with epilepsy (29,677 controls and 15,212 cases) and seven psychiatric comorbidities (485,436 controls and 269,495 cases) were identified from genome-wide association studies. Causal significance was estimated using inverse variance weighting. Sensitivity analyses included the weighted median, MR-Egger, and MR-PRESSO. The psychiatric comorbidities analyzed in this study included attention deficit hyperactivity disorder (ADHD), autism spectrum disorder, major depressive disorder, bipolar disorder, schizophrenia, obsessive-compulsive disorder (OCD), and anorexia nervosa.

RESULTS

Both forward and reverse genetic associations were observed for the selected psychiatric disorders. Notably, ADHD was significantly associated with an increased risk of generalized epilepsy (odds ratio [OR], 1.09; 95 % confidence interval [CI], 1.01-1.18; p = 0.013). However, MR-PRESSO detected the existence of pleiotropy (p = 0.001). Additionally, focal epilepsy was significantly associated with a higher risk of OCD (OR, 1.44; 95 % CI, 1.08-1.92; p = 0.013), and all sensitivity tests yielded favorably nonsignificant results. There was no significant genetic association between epilepsy and other examined psychiatric disorders. However, due to the detection of pleiotropy by MR-Egger and considerations related to the threshold for genetic instruments, a cautious approach is warranted in interpreting some of the results.

CONCLUSIONS

This study revealed significant genetic causality between focal epilepsy and OCD, as well as between ADHD and generalized epilepsy. However, no casual significance was observed with other psychiatric comorbidities examined. Considering the inherent limitations of MR studies, further research is warranted to definitively clarify these genetic causal associations.

Epilepsy and psychosis

Psychotic disorders are eight times more frequent in epilepsy than in the general population. The various clinical syndromes are classified according to their chronology of onset in relation to epileptic seizures: ictal psychoses (during epileptic discharge), post-ictal psychoses (PIP, after a seizure), interictal psychoses (IIP, with no chronological link) and those related to complete seizure control. Antiepileptic drugs can cause psychotic disorders in all these situations. Post-ictal psychoses (PIP) are affective psychoses that occur after a lucid interval lasting 12 to 120hours following a cluster of seizures. They last an average of 10days, with an abrupt beginning and end. PIP are directly linked to epileptic seizures, and disappear when the epilepsy is controlled. Interictal psychoses are schizophrenias. The management of psychotic disorders in epilepsy is neuropsychiatric, and requires close collaboration between epileptologists and psychiatrists. Antipsychotics can be prescribed in persons with epilepsy. Even today, psychotic disorders in epilepsy are poorly understood, under-diagnosed and under-treated.

Behavioral Deficits in Mice with Postnatal Disruption of Ndel1 in Forebrain Excitatory Neurons: Implications for Epilepsy and Neuropsychiatric Disorders

Dysfunction of nuclear distribution element-like 1 (Ndel1) is associated with schizophrenia, a neuropsychiatric disorder characterized by cognitive impairment and with seizures as comorbidity. The levels of Ndel1 are also altered in human and models with epilepsy, a chronic condition whose hallmark feature is the occurrence of spontaneous recurrent seizures and is typically associated with comorbid conditions including learning and memory deficits, anxiety, and depression. In this study, we analyzed the behaviors of mice postnatally deficient for Ndel1 in forebrain excitatory neurons (Ndel1 CKO) that exhibit spatial learning and memory deficits, seizures, and shortened lifespan. Ndel1 CKO mice underperformed in species-specific tasks, that is, the nest building, open field, Y maze, forced swim, and dry cylinder tasks. We surveyed the expression and/or activity of a dozen molecules related to Ndel1 functions and found changes that may contribute to the abnormal behaviors. Finally, we tested the impact of Reelin glycoprotein that shows protective effects in the hippocampus of Ndel1 CKO, on the performance of the mutant animals in the nest building task. Our study highlights the importance of Ndel1 in the manifestation of species-specific animal behaviors that may be relevant to our understanding of the clinical conditions shared between neuropsychiatric disorders and epilepsy.

Genetic Effects of the Schizophrenia-Related Gene DTNBP1 in Temporal Lobe Epilepsy

Recent studies have reported patients who concurrently exhibit conditions of epilepsy and schizophrenia, indicating certain shared pathologies between them. This study aimed to investigate the genetic effects of the schizophrenia-related gene DTNBP1 in temporal lobe epilepsy (TLE). A total of 496 TLE patients and 528 healthy individuals were successfully genotyped for six DTNBP1 polymorphisms (rs760665, rs1011313, rs2619528, rs2619522, rs909706, and rs2619538), including 335 TLE patients and 325 healthy controls in cohort 1, and 161 TLE patients and 203 healthy controls in cohort 2. The frequency of the TT genotype at rs909706 T > C was lower in TLE patients than in normal controls in the initial cohort (cohort 1), which was confirmed in an independent cohort (cohort 2). However, the intronic T allele failed to be in linkage disequilibrium (LD) with any functional variations nearby; thus, together with the CCAC and TCAT haplotypes (rs1011313-rs2619528-rs2619522-rs909706) observed in the study, this allele acts only as a protective factor against susceptibility to TLE. Meanwhile, a novo mutant allele rs2619538 T > A was exclusively observed in TLE patients, and a dual-luciferase assay revealed that the mutant allele was increased by approximately 22% in the DTNBP2 promoter compared with the wild-type allele. Together with the trend of increasing DTNBP1 expression in epilepsy patients and animal models in this study, these are the first findings to demonstrate the genetic association of DTNBP1 with TLE. Homozygous mutation of rs2619538 T > A likely promotes DTNBP1 expression and facilitates subsequent processes in epilepsy pathologies. Thus, the role of DTNBP1 in TLE deserves further exploration in the future.