Suicidal behavior and antiepileptic drugs in epilepsy: analysis of the emerging evidence

Risk of suicide and suicide-related events in subjects treated with antiseizure medications

INTRODUCTION

In the United States, it is reported that 1.4% of the general population commits suicide. It has been postulated that antiseizure medications (ASMs) can lead to the development of suicidal ideation and suicidal behavior; however, this risk is still very low and has yet to be precisely established.

AREAS COVERED

This narrative review evaluates the risk of suicide-related events (SREs) in subjects taking ASMs for various neurological disorders. Screening tools for suicidal ideation and suicidal behavior are also discussed. References for this article were found using PubMed/MEDLINE.

EXPERT OPINION

Although some ASMs can be associated with SREs, this is not yet clearly established. The mechanisms involved in suicide risk in subjects taking ASMs are multifactorial. The bidirectional relationship between depression and epilepsy, as well as other associations, should be kept in mind when interpreting any impact of ASMs in PWE. Screening for SREs, close monitoring of subjects taking ASMs are the most appropriate strategies to minimize suicide risk. More efforts should be made to achieve accurate risk stratification through prognostic models that could be applied to subjects taking ASMs. Studies exploring the association between ASMs and suicide should consider ASMs individually and control for prior SREs.

Evaluation of common prescription analgesics and adjuvant analgesics as markers of suicide risk: a longitudinal population-based study in England

Background

Analgesics prescriptions may provide a marker for identifying individuals at higher risk of suicide. In particular, awareness of which analgesics are implicated may help clinicians assess and modify risk.

Method

A case-control study in England using the Clinical Practice Research Datalink (for primary care records) linked with hospital and national mortality electronic registries. We included patients aged ≥15 who died by suicide between 2001 and 2019 (N = 14,515), to whom we individually matched 580,159 controls by suicide date and general practice (N = 594,674). Odds ratios (ORs) for suicide, controlled for age and sex, were assessed using conditional logistic regression.

Findings

Suicide risks were highest in those prescribed adjuvant analgesics (pregabalin, gabapentin and carbamazepine) (adjusted OR 4.07; 95% confidence intervals CI: 3.62-4.57), followed by those prescribed opioids (adjusted OR 2.01; 95% CI: 1.88-2.15) and those prescribed non-opioid analgesics (adjusted OR 1.48; 95% CI: 1.39-1.58) compared to those not prescribed these medications. By individual analgesic, the highest suicide risks were seen in patients prescribed oxycodone (adjusted OR 6.70; 95% CI: 4.49-9.37); pregabalin (adjusted OR 6.50; 95% CI: 5.41-7.81); morphine (adjusted OR 4.54; 95% CI: 3.73-5.52); and gabapentin (adjusted OR 3.12; 95% CI: 2.59-3.75). Suicide risk increased linearly with the number of analgesic prescriptions in the final year (p < 0.01 based on the likelihood ratio test), and the more different analgesics categories were prescribed in the final year (p < 0.01 based on the likelihood ratio test).

Interpretation

Analgesic prescribing was associated with higher suicide risk. This is a particular issue with regard to adjuvant non-opiate analgesics.

Funding

There was no funding for this study.

Multipronged Attack of Stem Cell Therapy in Treating the Neurological and Neuropsychiatric Symptoms of Epilepsy

Epilepsy stands as a life-threatening disease that is characterized by unprovoked seizures. However, an important characteristic of epilepsy that needs to be examined is the neuropsychiatric aspect. Epileptic patients endure aggression, depression, and other psychiatric illnesses. Therapies for epilepsy can be divided into two categories: antiepileptic medications and surgical resection. Antiepileptic drugs are used to attenuate heightened neuronal firing and to lessen seizure frequency. Alternatively, surgery can also be conducted to physically cut out the area of the brain that is assumed to be the root cause for the anomalous firing that triggers seizures. While both treatments serve as viable approaches that aim to regulate seizures and ameliorate the neurological detriments spurred by epilepsy, they do not serve to directly counteract epilepsy's neuropsychiatric traits. To address this concern, a potential new treatment involves the use of stem cells. Stem cell therapy has been employed in experimental models of neurological maladies, such as Parkinson's disease, and neuropsychiatric illnesses like depression. Cell-based treatments for epilepsy utilizing stem cells such as neural stem cells (NSCs), mesenchymal stem cells (MSCs), and interneuron grafts have been explored in preclinical and clinical settings, highlighting both the acute and chronic stages of epilepsy. However, it is difficult to create an animal model to capitalize on all the components of epilepsy due to the challenges in delineating the neuropsychiatric aspect. Therefore, further preclinical investigation into the safety and efficacy of stem cell therapy in addressing both the neurological and the neuropsychiatric components of epilepsy is warranted in order to optimize cell dosage, delivery, and timing of cell transplantation.

Associations between gabapentinoids and suicidal behaviour, unintentional overdoses, injuries, road traffic incidents, and violent crime: population based cohort study in Sweden

OBJECTIVE

To examine associations between gabapentinoids and adverse outcomes related to coordination disturbances (head or body injuries, or both and road traffic incidents or offences), mental health (suicidal behaviour, unintentional overdoses), and criminality.

DESIGN

Population based cohort study.

SETTING

High quality prescription, patient, death, and crime registers, Sweden.

PARTICIPANTS

191 973 people from the Swedish Prescribed Drug Register who collected prescriptions for gabapentinoids (pregabalin or gabapentin) during 2006 to 2013.

MAIN OUTCOME MEASURES

Primary outcomes were suicidal behaviour, unintentional overdoses, head/body injuries, road traffic incidents and offences, and arrests for violent crime. Stratified Cox proportional hazards regression was conducted comparing treatment periods with non-treatment periods within an individual. Participants served as their own control, thus accounting for time invariant factors (eg, genetic and historical factors), and reducing confounding by indication. Additional adjustments were made by age, sex, comorbidities, substance use, and use of other antiepileptics.

RESULTS

During the study period, 10 026 (5.2%) participants were treated for suicidal behaviour or died from suicide, 17 144 (8.9%) experienced an unintentional overdose, 12 070 (6.3%) had a road traffic incident or offence, 70 522 (36.7%) presented with head/body injuries, and 7984 (4.1%) were arrested for a violent crime. In within-individual analyses, gabapentinoid treatment was associated with increased hazards of suicidal behaviour and deaths from suicide (age adjusted hazard ratio 1.26, 95% confidence interval 1.20 to 1.32), unintentional overdoses (1.24, 1.19 to 1.28), head/body injuries (1.22, 1.19 to 1.25), and road traffic incidents and offences (1.13, 1.06 to 1.20). Associations with arrests for violent crime were less clear (1.04, 0.98 to 1.11). When the drugs were examined separately, pregabalin was associated with increased hazards of all outcomes, whereas gabapentin was associated with decreased or no statistically significant hazards. When stratifying on age, increased hazards of all outcomes were associated with participants aged 15 to 24 years.

CONCLUSIONS

This study suggests that gabapentinoids are associated with an increased risk of suicidal behaviour, unintentional overdoses, head/body injuries, and road traffic incidents and offences. Pregabalin was associated with higher hazards of these outcomes than gabapentin.

Usefulness of the Liverpool Adverse Events Profile for predicting a high risk of suicidality in people with drug-resistant epilepsy

PURPOSE

Suicidality including suicidal ideation and attempt has been a critical issue in people with epilepsy, especially in people with drug-resistant epilepsy (PWDRE). Clinicians commonly ask about adverse effects of antiepileptic drugs (AEDs) using something like the Liverpool Adverse Events Profile (LAEP) at epilepsy clinics, but suicide is usually not of interest. A high risk of suicidality can increase mortality by committing suicide in PWDRE. This study aimed to investigate whether clinicians can discern a high risk of suicidality in PWDRE by referring to the LAEP.

METHODS

We recruited PWDRE, aged from 19 to 68. They completed the 21-item LAEP, the suicidality module of the Mini International Neuropsychiatric Interview, and the Neurological Disorders Depression Inventory for Epilepsy (NDDI-E). Through receiver operating characteristic curve analysis, we tested the usefulness of LAEP to detect a high risk of suicide. By this, we determined each cutoff point of the total LAEP score and the number of severe LAEP items, for detecting the risk.

RESULTS

A hundred forty-four PWDRE participated in this study. Among them, 36 PWDRE (25.0%) had a high risk of suicidality. Either >45 of the total LAEP score or >8 of the number of severe LAEP items was a suggested optimal cutoff point for discerning the high risk of suicidality. LAEP had a correlation with the suicidality item of the NDDI-E.

CONCLUSION

The LAEP may inform a high risk of suicidality in PWDRE. Referring to this, clinicians can discern suicidal problems in their epilepsy clinics.

Contemplating stem cell therapy for epilepsy-induced neuropsychiatric symptoms

Epilepsy is a debilitating disease that impacts millions of people worldwide. While unprovoked seizures characterize its cardinal symptom, an important aspect of epilepsy that remains to be addressed is the neuropsychiatric component. It has been documented for millennia in paintings and literature that those with epilepsy can suffer from bouts of aggression, depression, and other psychiatric ailments. Current treatments for epilepsy include the use of antiepileptic drugs and surgical resection. Antiepileptic drugs reduce the overall firing of the brain to mitigate the rate of seizure occurrence. Surgery aims to remove a portion of the brain that is suspected to be the source of aberrant firing that leads to seizures. Both options treat the seizure-generating neurological aspect of epilepsy, but fail to directly address the neuropsychiatric components. A promising new treatment for epilepsy is the use of stem cells to treat both the biological and psychiatric components. Stem cell therapy has been shown efficacious in treating experimental models of neurological disorders, including Parkinson's disease, and neuropsychiatric diseases, such as depression. Additional research is necessary to see if stem cells can treat both neurological and neuropsychiatric aspects of epilepsy. Currently, there is no animal model that recapitulates all the clinical hallmarks of epilepsy. This could be due to difficulty in characterizing the neuropsychiatric component of the disease. In advancing stem cell therapy for treating epilepsy, experimental testing of the safety and efficacy of allogeneic and autologous transplantation will require the optimization of cell dosage, delivery, and timing of transplantation in a clinically relevant model of epilepsy with both neurological and neuropsychiatric symptoms of the disease as the primary outcome measures.

Perampanel: A Review in Drug-Resistant Epilepsy

Perampanel (Fycompa®), an orally-active, selective, noncompetitive α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonist, is a first-in-class antiepileptic drug (AED) offering the convenience of once-daily administration. In the EU and US, perampanel is approved in patients with epilepsy aged ≥12 years for the adjunctive treatment of primary generalized tonic-clonic seizures (GTCS) and partial-onset seizures (POS; with or without secondary generalization). In phase III trials of 17 or 19 weeks' duration, add-on perampanel ≤12 mg/day significantly improved seizure control in patients aged ≥12 years who were experiencing either primary GTCS or POS (with or without secondary generalization), despite ongoing treatment with stable dosages of one to three AEDs. Improvements in seizure control were maintained for up to 2 years in extensions of these core studies. Perampanel also provided sustained seizure control for up to ≈4 years in an extension of two phase II studies in patients aged ≥18 years with drug-resistant POS. Adjunctive perampanel therapy was generally well tolerated. Treatment-emergent adverse events were most commonly CNS-related (e.g. dizziness, somnolence, fatigue and irritability) and dose-related; however, most were of mild to moderate intensity. Clinical experience with perampanel is accumulating, although comparative studies and pharmacoeconomic data that could assist in positioning it relative to other AEDS that are approved and/or recommended as adjunctive therapy are lacking. Nonetheless, on the basis of its overall clinical profile and unique mechanism of action, perampanel is a useful additional adjunctive treatment option for patients with drug-resistant POS, with or without secondary generalization, and primary GTCS.

Third International Congress on Epilepsy, Brain, and Mind: Part 2

Epilepsy is both a disease of the brain and the mind. Here, we present the second of two papers with extended summaries of selected presentations of the Third International Congress on Epilepsy, Brain and Mind (April 3-5, 2014; Brno, Czech Republic). Humanistic, biologic, and therapeutic aspects of epilepsy, particularly those related to the mind, were discussed. The extended summaries provide current overviews of epilepsy, cognitive impairment, and treatment, including brain functional connectivity and functional organization; juvenile myoclonic epilepsy; cognitive problems in newly diagnosed epilepsy; SUDEP including studies on prevention and involvement of the serotoninergic system; aggression and antiepileptic drugs; body, mind, and brain, including pain, orientation, the "self-location", Gourmand syndrome, and obesity; euphoria, obsessions, and compulsions; and circumstantiality and psychiatric comorbidities.

Are children affected by epileptic neuropsychiatric comorbidities?

Childhood-onset epilepsy is associated with psychiatric and cognitive difficulties and with poor social outcomes in adulthood. Some antiepileptic drugs adversely affect behavior in susceptible children with easy-to-control or refractory epilepsies, contributing to a high risk of psychological and psychiatric disturbance. Studies had demonstrated that patients with benign rolandic epilepsy and absence epilepsy had more aggressive behavior, depression, and anxiety disorders than control children. Psychiatric comorbidities are strongly associated with a poor long-term health-related quality of life in childhood-onset epilepsy, which suggests that comprehensive epilepsy care must include screening and long-term treatment for these conditions, even if seizures remit.

Psychiatric comorbidity and social aspects in pregnant women with epilepsy - the Norwegian Mother and Child Cohort Study

OBJECTIVE

The objective of this study was to investigate psychiatric disease and social aspects in young women with epilepsy before and during pregnancy.

METHOD

The study included self-reported data from 106,935 pregnancies.

RESULTS

Seven hundred eleven women reported having epilepsy, and 45.9% of them were using antiepileptic drugs (AEDs). Compared to the reference group, self-reported eating disorders and depression were increased in the untreated epilepsy group before pregnancy. Both AED-treated and untreated women with epilepsy reported higher depression scores as assessed by the Hopkins Symptom Checklist, and the Lifetime Major Depression scale was increased in AED-treated women. Antiepileptic drug treatment was linked to low income (27.4% vs. 18.4%, p<0.001) and no income (5.5% vs. 2.6%, p=0.001). Low educational level was associated with epilepsy in AED-treated and untreated women (50.5%, p<0.001 and 46.9%, p<0.001 vs. 32.2%), as was unemployment due to disability (7.9%, p<0.001 and 6.5%, p<0.001 vs. 1.5%) and single parenting (4.4%, p=0.016 and 4.5%, p=0.007 vs. 2.4%). No difference was found for smoking, alcohol use, or narcotic use.

CONCLUSION

Symptoms of depression were associated with epilepsy both during and before pregnancy. Epilepsy was linked to eating disorders before pregnancy. Unemployment, single parenting, and low educational level were linked to epilepsy in young pregnant females. Efforts aiming at treatment and screening for psychiatric comorbidity in pregnant women with epilepsy are important in the follow-up of these patients.

Temporal trends in new exposure to antiepileptic drug monotherapy and suicide-related behavior

OBJECTIVE

Because some recent studies suggest increased risk for suicide-related behavior (SRB; ideation, attempts) among those receiving antiepileptic drugs (AEDs), we examined the temporal relationship between new AED exposure and SRB in a cohort of older veterans.

METHODS

We used national Veterans Health Administration databases to identify veterans aged ≥65 years who received a new AED prescription in 2004-2006. All instances of SRB were identified using ICD-9-CM codes 1 year before and after the AED exposure (index) date. We also identified comorbid conditions and medication associated with SRB in prior research. We used generalized estimating equations with a logit link to examine the association between new AED exposure and SRB during 30-day intervals during the year before and after the index date, controlling for potential confounders.

RESULTS

In this cohort of 90,263 older veterans, the likelihood of SRB the month prior to AED exposure was significantly higher than in other time periods even after adjusting for potential confounders. Although there were 87 SRB events (74 individuals) the year before and 106 SRB events (92 individuals) after, approximately 22% (n = 16) of those also had SRB before the index date. Moreover, the rate of SRB after AED start was gradually reduced over time.

CONCLUSIONS

The temporal pattern of AED exposure and SRB suggests that, in clinical practice, the peak in SRB is prior to exposure. While speculative, the rate of gradual reduction in SRB thereafter suggests that symptoms may prompt AED prescription.

Epilepsy, cognition, and neuropsychiatry (Epilepsy, Brain, and Mind, part 2)

Epilepsy is, of course, not one disease but rather a huge number of disorders that can present with seizures. In common, they all reflect brain dysfunction. Moreover, they can affect the mind and, of course, behavior. While animals too may suffer from epilepsy, as far as we know, the electrical discharges are less likely to affect the mind and behavior, which is not surprising. While the epileptic seizures themselves are episodic, the mental and behavioral changes continue, in many cases, interictally. The episodic mental and behavioral manifestations are more dramatic, while the interictal ones are easier to study with anatomical and functional studies. The following extended summaries complement those presented in Part 1.

Impact of psychotropic drugs on suicide and suicidal behaviors

OBJECTIVE

To examine the impact of psychotropic drugs on suicide and suicidal behaviors in bipolar disorders.

METHODS

A Medline search of articles published from January 1960 to January 2013 was performed using relevant keywords to identify studies examining the relationship of psychotropic drugs to suicidal behaviors. The publications were further reviewed for relevant references and information. Additionally, the US Food and Drug Administration Center for Drug Evaluation Research website was searched.

RESULTS

The available studies used differing methodologies, making interpretation of the findings difficult. Studies suggest that antidepressants may increase suicidal risk in bipolar disorder, this possibly being related to the induction of broadly defined mixed states. There is no evidence that antiepileptic drugs as a class increase suicidal risk in patients with bipolar disorder. Only lithium provides convincing data that it reduces the risk of suicide over the long term. There is little known regarding the effects of antipsychotics, as well as anti-anxiety and hypnotic drugs, on suicidal behavior.

CONCLUSIONS

The available evidence for the impact of psychotropics on suicidal risk in patients with bipolar disorder is largely methodologically flawed and, except for a few instances, clinically not useful at this point. Adequately powered, prospective randomized controlled studies are needed to assess the impact of each class of psychotropic and each psychotropic as well as common combination therapies. Until such studies have been carried out, clinicians are urged to exercise caution in using these drugs and rely on the traditional means of carefully assessing and monitoring patients with bipolar disorder who are at high risk for suicide.

Suicide risk in people with epilepsy taking antiepileptic drugs

OBJECTIVES

The standardized mortality ratio for suicide in people with epilepsy is reported as 5.1 [95% confidence interval (CI): 3.9-6.6], but this is only partially explained by the high rates of psychiatric comorbidity. This issue was revived when, in 2008, the Food and Drug Administration (FDA) issued an alert on an increased risk of suicide in people taking antiepileptic drugs (AEDs). We discuss and elaborate on available evidence on the interplay among epilepsy, suicide, and AEDs, taking into account the phenomenology of mood disorders in people with epilepsy and the psychotropic potential of AEDs.

METHODS

Articles were identified by searches of Medline/PubMed using the terms epilepsy, antiepileptic drugs, and suicide. Only papers published in English in international peer-reviewed journals were considered. The reference lists of relevant articles were hand-searched for additional publications (e.g., book chapters or review papers) if relevant to the discussion.

RESULTS

The results of studies supporting or opposing the FDA conclusions have been inconsistent. This may be due to a number of methodological limitations, such as the failure to adjust for past suicidality and the confounding effect of epilepsy.

CONCLUSIONS

A subgroup of people with epilepsy appears to be at risk of developing treatment-emergent psychiatric adverse effects of AEDs independently of the specific mechanism of action of the drug. Clinicians need to pay attention not only to seizure patterns when choosing the appropriate AED but also to a number of different parameters, not least the mental state of the individual patient.

Lamotrigine positively affects the development of psychiatric comorbidity in epileptic animals, while psychiatric comorbidity aggravates seizures

Several clinical and preclinical studies have focused on the relationship between epilepsy and psychological disturbances. Although behavior in some experimental models of epilepsy has been studied, only few of them can be considered as models of epilepsy and mood disorder comorbidity. Since several models of epilepsy or psychiatric disorders are already available, we wondered whether a mixture of the two could experimentally represent a valid alternative to study such comorbidity. Here, we present a possible experimental protocol to study drug effects and physiopathogenesis of psychiatric comorbidity in epileptic animals. Pentylentetrazol-kindled animals were subjected to the chronic mild stress (CMS) procedure; furthermore, we tested the effects of chronic lamotrigine treatment on the development of comorbidity. We found that epileptic-depressed animals showed more pronounced behavioral alterations in comparison to other mice groups, indicating that kindled animals develop more pronounced CMS-induced behavioral alterations than nonepileptic mice; lamotrigine was able to prevent the development of comorbidities such as anxiety, depression-like behavior, and memory impairment.

Ideal characteristics of an antiepileptic drug: how do these impact treatment decisions for individual patients?

Effective management of epilepsy requires a holistic approach that takes into account the needs of the individual patient. Antiepileptic drug (AED) treatment must therefore look beyond efficacy to ensure that the patient's overall health status and quality of life (QoL) are optimized. Because the primary objective of AED treatment is to control seizures over the long term, the ideal AED should, first and foremost, demonstrate sustained efficacy and favourable tolerability. In addition, it should have a broad spectrum of activity; its pharmacokinetic profile should be stable and predictable and allow the option of once-daily dosing; and it should not interact with other medications and concomitant AEDs. Because the efficacy of first-line AEDs is broadly comparable, choice of treatment should be based on the individual patient's specific clinical characteristics. In particular, the primary and secondary prevention of comorbid conditions should be taken into consideration, because this can reduce the risk of mortality and improve health outcomes and QoL. Treatment selection must also take into account the patient's particular lifestyle and priorities, to maximize the likelihood of long-term treatment adherence. Advances in genetic testing may help inform choice of treatment - not only by elucidating a patient's underlying aetiology, but also by helping to avoid unnecessary side effects. Although certain patient populations (e.g. women of childbearing potential, adolescents, the elderly) require particular consideration when choosing the most appropriate treatment, every patient's unique clinical characteristics and personal circumstances must be taken into account to ensure treatment success and optimize their QoL.

Uncovering the neurobehavioural comorbidities of epilepsy over the lifespan

Epilepsy is a common neurological disorder that is complicated by psychiatric, cognitive, and social comorbidities that have become a major target of concern and investigation in view of their adverse effect on the course and quality of life. In this report we define the specific psychiatric, cognitive, and social comorbidities of paediatric and adult epilepsy, their epidemiology, and real life effects; examine the relation between epilepsy syndromes and the risk of neurobehavioural comorbidities; address the lifespan effect of epilepsy on brain neurodevelopment and brain ageing and the risk of neurobehavioural comorbidities; consider the overarching effect of broader brain disorders on both epilepsy and neurobehavioural comorbidities; examine directions of causality and the contribution of selected epilepsy-related characteristics; and outline clinic-friendly screening approaches for these problems and recommended pharmacological, behavioural, and educational interventions.

Antiepileptic drugs and suicidality: an expert consensus statement from the Task Force on Therapeutic Strategies of the ILAE Commission on Neuropsychobiology

In 2008, the U.S. Food and Drug Administration (FDA) issued an alert to health care professionals about an increased risk of suicide ideation and suicide behavior in people treated with antiepileptic drugs (AEDs). Since then, a number of retrospective cohort and case-control studies have been published that are trying to address this issue, but gathered results are contradictory. This report represents an expert consensus statement developed by an ad hoc task force of the Commission on Neuropsychobiology of the International League Against Epilepsy (ILAE). Although some (but not all) AEDs can be associated with treatment-emergent psychiatric problems that can lead to suicidal ideation and behavior, the actual suicidal risk is yet to be established, but it seems to be very low. The risk of stopping AEDs or refusing to start AEDs is significantly worse and can actually result in serious harm including death to the patient. Suicidality in epilepsy is multifactorial, and different variables are operant. Clinicians should investigate the existence of such risk factors and adopt appropriate screening instruments. If necessary, patients should be referred for a psychiatric evaluation, but AED treatment should not be withheld, even in patients with positive suicidal risks. When starting an AED or switching from one to other AEDs, patients should be advised to report to their treating physician any change in mood and suicidal ideation. Data on treatment-emergent psychiatric adverse events need to be collected, in addition to general safety information, during controlled studies in order to have meaningful information for patients and their relatives when a new drug is marketed.

Rhythm and blues: animal models of epilepsy and depression comorbidity

Clinical evidence shows a strong, bidirectional comorbidity between depression and epilepsy that is associated with decreased quality of life and responsivity to pharmacotherapies. At present, the neurobiological underpinnings of this comorbidity remain hazy. To complicate matters, anticonvulsant drugs can cause mood disturbances, while antidepressant drugs can lower seizure threshold, making it difficult to treat patients suffering from both depression and epilepsy. Animal models have been created to untangle the mechanisms behind the relationship between these disorders and to serve as screening tools for new therapies targeted to treat both simultaneously. These animal models are based on chemical interventions (e.g. pentylenetetrazol, kainic acid, pilocarpine), electrical stimulations (e.g. kindling, electroshock), and genetic/selective breeding paradigms (e.g. genetically epilepsy-prone rats (GEPRs), genetic absence epilepsy rat from Strasbourg (GAERS), WAG/Rij rats, swim lo-active rats (SwLo)). Studies on these animal models point to some potential mechanisms that could explain epilepsy and depression comorbidity, such as various components of the dopaminergic, noradrenergic, serotonergic, and GABAergic systems, as well as key brain regions, like the amygdala and hippocampus. These models have also been used to screen possible therapies. The purpose of the present review is to highlight the importance of animal models in research on comorbid epilepsy and depression and to explore the contributions of these models to our understanding of the mechanisms and potential treatments for these disorders.

Behavioral adverse effects of antiepileptic drugs in epilepsy

Patient tolerability is a significant limiting factor in the treatment of epilepsy and adverse effect profiles often determine drug retention rates. A full appreciation of the behavioral effects of a wide range of antiepileptic drugs (AEDs) is therefore essential to make informed treatment decisions. In this timely review, we highlight key alterations in mood, emotional experience, and other behavioral/psychiatric features, which can exert a crucial impact on patients' quality of life and well-being. With a view to prescribing both in general and in relation to more specific clinical characteristics, the evidence reviewed indicates that the incidence and characteristics of behavioral effects may be related to age, epilepsy type, the presence of learning disability, and previous psychiatric history. Medication parameters including dosage, titration rate, efficacy in controlling seizures, and concurrent AEDs can also contribute to the occurrence of behavioral effects. However, there are a number of limitations in drawing conclusions from the available literature. These include variation in study design, treatment group, and assessment tools that lead to difficulties comparing findings across studies, and problems with the consistency of available information relating to the study methodology. Future longitudinal studies assessing the impact of tolerance or developmental change on behavioral effects and specific studies comparing the effects of commonly prescribed agents across subgroups of patients with epilepsy will make an informative contribution to the available literature. A valuable outcome of further research may be the development of specific instruments that are sensitive to the behavioral effects associated with particular AEDs.

Non-vision adverse events with vigabatrin therapy

Vigabatrin is an effective antiepileptic drug (AED) for the treatment of refractory complex partial seizures (rCPS) and infantile spasms (IS). In clinical trials, vigabatrin was generally well-tolerated with an adverse event profile similar to that of other AEDs. The most common treatment-related adverse events were central nervous system effects, including drowsiness, dizziness, headache, and fatigue, with adjunctive vigabatrin in adults with rCPS, and sedation, somnolence, and irritability with vigabatrin monotherapy in infants with IS. Vigabatrin had little effect on cognitive function, mood, or behavior in a battery of neuropsychologic tests for rCPS. In placebo-controlled clinical trials, the incidence of depression and psychosis, but not other psychiatric adverse events, was greater with vigabatrin than placebo. Intramyelinic edema (IME) was initially identified in rats and dogs and led to a temporary suspension of clinical trials in the United States. IME was subsequently correlated with delays in evoked potential (EP) and increased T(2) -weighted signals on magnetic resonance imaging (MRI). Clinical trials of vigabatrin were allowed to resume after IME was not detected by neuropathologic assessments of autopsy and neurosurgical specimens or by serial EP or MRI assessments in older children and adults receiving vigabatrin. Subsequently, MRI abnormalities characterized by increased T(2) intensity and restricted diffusion were identified in infants treated with vigabatrin for IS. These abnormalities generally resolved with discontinuation of vigabatrin and, in some cases, during continued therapy. The benefit of improved seizure control must be balanced against the potential risks associated with vigabatrin, including abnormal MRI changes and other vigabatrin-related safety issues.