Cognitive effects of topiramate, gabapentin, and lamotrigine in healthy young adults

Impaired verbal fluency under topiramate--evidence for synergistic negative effects of epilepsy, topiramate, and polytherapy

BACKGROUND AND PURPOSE

Treatment with topiramate (TPM) is known to negatively affect executive functions and verbal fluency in particular. However, judgments of cognitive side effects under TPM rarely consider clinical conditions and possible effects of epilepsy, treatment, and drug load.

METHODS

This retrospective cross-sectional study in large cohorts of patients with epilepsy evaluated the impact of TPM mono- and polytherapy on verbal fluency. To isolate TPM-induced effects from those of epilepsy and antiepileptic medication in general, verbal fluency under TPM (N = 421) was compared to the performance of a matched sample of patients with an antiepileptic medication other than TPM (N = 351), untreated patients (N = 108), and healthy controls (N = 100).

RESULTS

Impaired verbal fluency performance was seen in 77% of the patients treated with TPM. Compared to healthy controls, verbal fluency in untreated patients was reduced by 22%, under monotherapy without TPM by 31% and under TPM monotherapy by 45%. With and without TPM, verbal fluency performance linearly decreased with each additional drug in polytherapy. On each level, performance under TPM was 21-28% worse than in the respective condition without TPM. Unimpaired performance under TPM was primarily associated with lower dose, higher education, and a later onset of epilepsy.

CONCLUSIONS

The majority of patients under TPM shows reduced verbal fluency. However, when taking the cumulative negative effects of epilepsy, and the concomitant drug regimen into account, TPM is associated with a 21-28% poorer performance as compared with other drugs. Additionally, the data indicate an impact of dose and reserve capacity on the occurrence of impairments.

The effect of topiramate plasma concentration on linguistic behavior, verbal recall and working memory

This is the first study of the effect of topiramate on linguistic behavior and verbal recall using a computational linguistics system for automated language and speech analysis to detect and quantify drug-induced changes in speech recorded during discourse-level tasks. Healthy volunteers were administered a single, 100-mg oral dose of topiramate in two double-blind, randomized, placebo-controlled, crossover studies. Subjects' topiramate plasma levels ranged from 0.23 to 2.81 μg/mL. We found a significant association between topiramate levels and impairment on measures of verbal fluency elicited during a picture description task, correct number of words recalled on a paragraph recall test, and reaction time recorded during a working memory task. Using the tools of clinical pharmacology and computational linguistics, we elucidated the relationship between the determinants of a drug's disposition as reflected in plasma concentrations and their impact on cognitive functioning as reflected in spoken language discourse.

Topiramate and its effect on fMRI of language in patients with right or left temporal lobe epilepsy

Topiramate (TPM) is well recognized for its negative effects on cognition, language performance and lateralization results on the intracarotid amobarbital procedure (IAP). But, the effects of TPM on functional MRI (fMRI) of language and the fMRI signals are less clear. Functional MRI is increasingly used for presurgical evaluation of epilepsy patients in place of IAP for language lateralization. Thus, the goal of this study was to assess the effects of TPM on fMRI signals. In this study, we included 8 patients with right temporal lobe epilepsy (RTLE) and 8 with left temporal lobe epilepsy (LTLE) taking TPM (+TPM). Matched to them for age, handedness and side of seizure onset were 8 patients with RTLE and 8 with LTLE not taking TPM (-TPM). Matched for age and handedness to the patients with TLE were 32 healthy controls. The fMRI paradigm involved semantic decision/tone decision task (in-scanner behavioral data were collected). All epilepsy patients received a standard neuropsychological language battery. One sample t-tests were performed within each group to assess task-specific activations. Functional MRI data random-effects analysis was performed to determine significant group activation differences and to assess the effect of TPM dose on task activation. Direct group comparisons of fMRI, language and demographic data between patients with R/L TLE +TPM vs. -TPM and the analysis of the effects of TPM on blood oxygenation level-dependent (BOLD) signal were performed. Groups were matched for age, handedness and, within the R/L TLE groups, for the age of epilepsy onset/duration and the number of AEDs/TPM dose. The in-scanner language performance of patients was worse when compared to healthy controls - all p<0.044. While all groups showed fMRI activation typical for this task, regression analyses comparing L/R TLE +TPM vs. -TPM showed significant fMRI signal differences between groups (increases in left cingulate gyrus and decreases in left superior temporal gyrus in the patients with LTLE +TPM; increases in the right BA 10 and left visual cortex and decreases in the left BA 47 in +TPM RTLE). Further, TPM dose showed positive relationship with activation in the basal ganglia and negative associations with activation in anterior cingulate and posterior visual cortex. Thus, TPM appears to have a different effect on fMRI language distribution in patients with R/L TLE and a dose-dependent effect on fMRI signals. These findings may, in part, explain the negative effects of TPM on cognition and language performance and support the notion that TPM may affect the results of language fMRI lateralization/localization.

Genetic and environmental correlates of topiramate-induced cognitive impairment

Topiramate is an antiepileptic drug that has marked treatment-limiting side effects on specific aspects of cognitive performance in both patients and healthy volunteers. Because these severe side effects occur only in certain individuals, identifying genetic or environmental variables that influence cognitive response would be of great utility in determining whether to administer this drug to a patient. We gave an acute 100 mg oral dose of topiramate to 158 healthy volunteers and measured how the drug changed their performance on a diverse battery of cognitive tests. We found a wide range of responses to topiramate, and we demonstrated that not all tests in the battery were equally affected. There was no correlation between the effect of topiramate and either education level or baseline cognitive performance. Of interest, there was an up to 55-fold variation in the topiramate plasma levels of the participants. Our genome-wide association study (GWAS) of cognitive response did not reveal any genome-wide significant associations; the study was powered to find variants explaining at least 25% of the variation in cognitive response. Combining the results of this GWAS with a retrospective study of cognitive complaints in 290 epilepsy patients who received topiramate as part of their treatment also did not result in a significant association. Our results support the need for additional genetic studies of topiramate that use larger sample sizes.

Gender and drug effects on neuroimaging in epilepsy

Men are different from women, and patients with epilepsy are different in many aspects from healthy control subjects. Quantitative or semiquantitative analysis of neuroimaging data depends on the comparison between either a single patient against a group of healthy or unaffected controls, or comparisons between groups of patients and controls. Matching for gender is desired, but is sometimes not possible, for example, in the case of nuclear medicine with women in childbearing age usually not being recruited as healthy controls. Antiepileptic drug treatment is the other major confounder for comparisons of cognitive functioning between patients and healthy control subjects. Whether these two covariates, gender and drug effects, are of interest or nuisance variables depends on the question and design of the neuroimaging study.

Newly diagnosed epilepsy: cognitive outcome after 12 months

PURPOSE

Cognitive impairment is a common comorbidity of epilepsy; however, relatively little research has been undertaken to investigate how cognitive problems develop in adults who are newly diagnosed. This study aimed to investigate changes in cognitive performance in adults with new-onset epilepsy 12 months after diagnosis compared with healthy volunteers.

METHODS

One hundred forty-seven people with epilepsy (PWE) were assessed using a comprehensive neuropsychological test battery before they started treatment and after 12 months. Cognitive change scores were compared with 69 healthy volunteers who were also assessed at baseline and after 12 months.

KEY FINDINGS

At 12 month follow-up, PWE had significantly poorer change scores for 9 of the 16 variables. For the majority of these measures, PWE had subtle declines in performance, whereas healthy volunteers improved. Poorer performance on some measures was associated with treatment with topiramate, generalized seizures and, interestingly, achieving an immediate 12-month seizure remission.

SIGNIFICANCE

After controlling for statistically confounding factors, people with newly diagnosed epilepsy had a different cognitive trajectory compared with healthy volunteers from the general population. Memory, psychomotor speed, and higher executive functioning were the domains most vulnerable to change over a 12-month period.

Clobazam as an adjunctive therapy in treating seizures associated with Lennox-Gastaut syndrome

Lennox-Gastaut syndrome (LGS) is a devastating childhood epilepsy syndrome characterized by the occurrence of multiple types of seizures and cognitive decline. Most children suffer from frequent seizures that are refractory to current medical management. Recent clinical trials have suggested that addition of clobazam may improve the clinical outcome for some LGS patients. Although clobazam has been available for over five decades, it has only recently been approved by the US Food and Drug Administration for this indication. As a 1,5-benzodiazepine, clobazam is structurally related to the widely used 1,4-benzodiazepines, which include diazepam. Clobazam has been shown to modulate GABAergic neurotransmission by positive allosteric modulation of GABA(A) receptors, and to increase expression of transporters for both GABA and glutamate. The active metabolite n-desmethylclobazam (norclobazam) also modulates GABA(A) receptors, and the relative importance of these two compounds in the clinical effectiveness of clobazam remains an open question. Clinical trials involving clobazam as an addon therapy in a variety of pediatric epilepsy populations have found a significant improvement in seizure control. In patients with LGS, clobazam may have greatest efficacy for drop seizures. Longstanding clinical experience suggests that clobazam is a safe and well tolerated antiepileptic drug with infrequent and mild adverse effects. These results suggest that adjunctive treatment with clobazam may be a reasonable option for LGS patients, particularly those who are treatment-resistant.

Cognitive effects of topiramate revealed by standardised low-resolution brain electromagnetic tomography (sLORETA) of event-related potentials

OBJECTIVE

To evaluate the effect of topiramate (TPM) on event-related potentials (ERPs) in patients with epilepsy.

METHODS

Neuropsychological tests and ERP study using auditory oddball paradigm were conducted before and after treatment with TPM in drug-naive epilepsy patients. To detect target brain regions in which ERP changed during the cognitive task, cortical current densities of ERP components were analysed using standardised low-resolution electromagnetic tomography (sLORETA).

RESULTS

Neuropsychological tests (n=18 patients) showed that TPM significantly decreased the score in digit span, Corsi block and Controlled Oral Word Association word fluency. Repeated-measures analysis of variance of ERP data (n=13 patients) revealed that P2 amplitude was significantly increased at Fz electrode following treatment with TPM. Statistical non-parametric map of sLORETA between pre- and post-TPM ERPs revealed that current density of P200 component was significantly reduced by TPM in bilateral parieto-occipital, temporolimbic and dorsolateral right prefrontal regions.

CONCLUSIONS

Our findings suggest that TPM affects selective brain regions which may be related to cognitive side effects.

SIGNIFICANCE

Source localisation of ERPs can be helpful in identifying target brain regions for the cognitive side effects of anti-epileptic drugs.

Newly diagnosed epilepsy: cognitive outcome at 5 years

Many people with epilepsy experience cognitive problems as a consequence of their epilepsy and its treatment. However, relatively few longitudinal studies have been conducted to investigate how these problems progress during the course of the disorder, particularly in those who are newly diagnosed. Fifty patients with newly diagnosed epilepsy were assessed using a comprehensive neuropsychological test battery before they started antiepileptic treatment and after a mean of 5 years. At the 5-year follow-up, the majority of cognitive measures remained stable, although significant (but subtle) declines were noted for memory and psychomotor speed domains in 38% of people with epilepsy.

Cognitive effects of levetiracetam versus topiramate

The Influence of Antiepileptic Drugs on Cognition: A Comparison of Levetiracetam with Topiramate. Gomer B, Wagner K, Frings L, Saar J, Carius A, Härle M, Steinhoff BJ, Schulze-Bonhage A. Epilepsy Behav 2007;10(3):486–494. Levetiracetam (LEV) and topiramate (TPM) are considered highly effective novel antiepileptic drugs (AEDs) in the treatment of focal epilepsies. To explore potential side effects, this study investigated their influence on cognitive functions comparatively by means of a standardized neuropsychological test battery assessing several cognitive domains. In this observational study, cognitive changes were explored in 30 consecutively recruited patients with focal epilepsy treated with LEV and in 21 patients treated with TPM, comparing functions assessed prior to gradual initiation and after reaching steady state of the individual target dosage. Before titration, patient groups did not differ significantly with respect to cognitive performance. Whereas the LEV group manifested no change in cognitive performance after AED titration, the TPM group worsened in the cognitive domains of cognitive speed and verbal fluency, as well as short-term memory. These findings suggest that TPM, unlike LEV, may impair frontal lobe functions. The lack of cognitive side effects related to LEV treatment may be relevant for treatment decisions.

Psychotropic effects of antiepileptic drugs

Antiepileptic drugs are important psychotropic agents that are commonly used to treat psychiatric disorders. The behavioral effects of antiepileptic drugs may differ between epilepsy and psychiatric patient populations. Randomized, double-blind, controlled data on the psychotropic efficacy of antiepileptic drugs are limited mainly to bipolar disorder.

Levetiracetam, lamotrigine, and phenobarbital in patients with epileptic seizures and Alzheimer's disease

The objective of the study described here was to evaluate the efficacy, tolerability, and cognitive effects of levetiracetam (LEV) in patients with seizures and Alzheimer's disease (AD). This was a prospective, randomized, three-arm parallel-group, case-control study of 95 patients taking LEV (n=38), phenobarbital (PB) (n=28), and lamotrigine (LTG) (n=29). A 4-week dose adjustment was followed by a 12-month evaluation period. The three groups were compared to a control group (n=68) to evaluate cognitive effects of the antiepileptic drugs. We examined drug effects cross-sectionally at baseline, 6 months, and 12 months. There were no significant differences in efficacy among the three AEDs. LEV caused fewer adverse events than the other AEDs. PB produced persistent negative cognitive side effects. LEV was associated with improved cognitive performance, specifically attention level and oral fluency items. LTG had a better effect on mood. LEV had a benign neuropsychological side effect profile, making it a cognitively safe drug to use for controlling established seizures in elderly patients with Alzheimer's disease.

Enhanced working and verbal memory after lamotrigine treatment in pediatric bipolar disorder

OBJECTIVE

To examine the treatment impact of lamotrigine on the neurocognitive profile of patients with pediatric bipolar disorder (PBD).

METHOD

Healthy controls (HC) (n = 24; mean age = 12.4 +/- 3.3 years) and unmedicated PBD patients with manic, mixed, or hypomanic episodes (n = 34; mean age = 13 +/- 3.1 years) were matched for IQ, age, sex, race, and socioeconomic status. A neurocognitive battery was administered at baseline and again after 14 weeks, during which PBD patients were treated with lamotrigine.

RESULTS

Clinical symptoms improved with treatment in the patient group with significant change from baseline to follow-up on the Young Mania Rating Scale (p < 0.001) and the Children's Depression Rating Scale-Revised (p < 0.001). Global neurocognitive function improved with lamotrigine in PBD patients over time relative to that in HC, although overall performance remained impaired. Working memory and verbal memory significantly improved with treatment in patients, and deficits in these domains were no longer significantly impaired relative to HC at follow-up. Executive function significantly improved with treatment in the patient group but still lagged behind HC at follow-up. Performance on attention tests did not improve with treatment.

CONCLUSIONS

There appears to be significant improvement in cognitive abilities in PBD patients treated with lamotrigine that is most prominent in the areas of working memory and verbal memory and that occurs along with mood stabilization.

Cognitive effects of topiramate in migraine patients aged 12 through 17 years

Neuropsychologic data are presented from a randomized, double-blind, placebo-controlled, multicenter study with placebo, topiramate 50 mg/day, and topiramate 100 mg/day. The Cambridge Neuropsychological Test Automated Battery (CANTAB) and cognitive adverse events were used to evaluate neurocognitive effects of topiramate. Topiramate 100 mg/day vs placebo was associated with slight statistically significant score increases, indicating slowing, from baseline vs placebo in three CANTAB measures: five-choice reaction time (P = 0.028), pattern recognition memory mean correct latency (P = 0.027), and rapid visual information processing mean latency (P = 0.040). No other patterns related to topiramate treatment were observed in measurements of learning, memory, and visual information processing, except for potential improvement with topiramate 100 mg/day vs placebo in spatial span total errors (accuracy test) (P = 0.040). The most common cognitive and neuropsychiatric adverse events with a higher incidence in the topiramate 50 and 100 mg/day groups vs placebo were anorexia (9% and 11% vs 3%), insomnia (9% and 3% vs 3%), fatigue (6% and 9% vs 6%), and dizziness (6% and 9% vs 0%). Thus, topiramate 100 mg/day was associated with modest increases in psychomotor reaction times. Learning, memory, and executive function were unchanged. The tolerability profile, including cognitive adverse events, appeared to be acceptable.

Association between attention-deficit/hyperactivity disorder and epilepsy in pediatric populations

There is a bidirectional relationship between attention-deficit/hyperactivity disorder (ADHD) and epilepsy. ADHD increases seizure risk, while patients with epilepsy have an increased prevalence of ADHD. The reasons explaining this association are not fully understood. Proposed mechanisms include effects of antiepileptic medications, underlying neurodevelopmental vulnerability, the effects of chronic seizures and subclinical epileptiform activity on cognitive functions and adrenergic dysfunction. There may also be a common genetic defect underlying both disorders in some families. Antiepileptics associated with ADHD-like side effects include phenobarbital, gabapentin, vigabatrin and topiramate. Methylphenidate has been studied in a double-blind setting against placebo for treatment of ADHD comorbid with epilepsy, and has a good risk-benefit ratio. Amphetamine, atomoxetine, clonidine and guanfacine only have case series to support their use and bupropion should be avoided.

Attention-deficit disorders and epilepsy in childhood: incidence, causative relations and treatment possibilities

At least 20% of children with epilepsy have clinical attention-deficit hyperactivity disorder (ADHD) compared to 3% to 7% of the general pediatric population. Several mechanisms may account for the high prevalence, such as a common genetic propensity, noradrenergic system dysregulation, subclinical epileptiform discharges, or even seizures, antiepileptic drug effects, and psychosocial factors. At the same time, children with attention-deficit hyperactivity disorder have a higher than normal rate of electroencephalography abnormalities (5.6-30.1% vs. 3.5%). Methylphenidate treatment is equally efficient in children with isolated attention-deficit hyperactivity disorder and in children with attention-deficit hyperactivity disorder and epilepsy (70%-77%). Electroencephalography screening in patients with attention-deficit hyperactivity disorder in the absence of other clinical indications or before starting methylphenidate treatment is not currently indicated. Methylphenidate is considered safe for use in children who are seizure-free. However, the few reports of seizure aggravation in methylphenidate-treated children with uncontrolled epilepsy have raised concern.

Epilepsy pharmacogenetics

Large interindividual variation in efficacy and adverse effects of anti-epileptic therapy presents opportunities and challenges in pharmacogenomics. Although the first true association of genetic polymorphism in drug-metabolizing enzymes with anti-epileptic drug dose was reported 10 years ago, most of the findings have had little impact on clinical practice so far. Most studies performed to date examined candidate genes and were focused on candidate gene selection. Genome-wide association and whole-genome sequencing technologies empower hypothesis-free comprehensive screening of genetic variation across the genome and now the main challenge remaining is to select and study clinically relevant phenotypes suitable for genetic studies. Here we review the current state of epilepsy pharmacogenetics focusing on phenotyping questions and discuss what characteristics we need to study to get answers.

The role of titration schedule of topiramate for the development of depression in patients with epilepsy

PURPOSE

To determine whether a fast titration schedule of topiramate (TPM) has different effects on the occurrence of depression, in relation to other risk factors for TPM-induced depression, including history of depression (HxDEP), febrile seizures (FS), and hippocampal sclerosis (HS).

METHODS

Using data from a large case registry of patients prescribed TPM, two models were constructed: Model 1 examined the independent effect of rapid TPM titration after separate adjustment for FS, HxDEP, and HS. Model 2 examined effect of the cooccurrence of rapid titration on the development of depression with each of these risk factors.

RESULTS

A total of 423 patients were included (51.8% females), mean age (SD) 35.5 (11.8) years, mean duration of epilepsy of 22.2 (11.5) years. Forty-four patients (10.4%) developed depression during TPM therapy. A rapid TPM titration was associated with 5-fold increased risk of depression that increased to 12.7-fold in the presence of both FS and rapid TPM titration, 23.3-fold in the presence of both HxDEP and rapid TPM titration, and 7.6-fold in the presence of both HS and rapid TPM titration schedule.

CONCLUSIONS

Our study suggests that a rapid titration schedule is associated with an increased risk of developing depression during TPM therapy. HxDEP and FS are major contraindications to the use of a rapid titration, with a 23.3-fold and 12.7 fold increased risk, respectively.

Acute topiramate differentially affects human aggressive responding at low vs. moderate doses in subjects with histories of substance abuse and antisocial behavior

Anticonvulsant drugs have demonstrated efficacy in the management of irritability and aggression in a variety of psychiatric populations. We examined the acute effects of topiramate on aggression using a laboratory model of human aggression (PSAP) in individuals at high risk for aggressive and violent behavior.Twelve subjects, on parole/probation and with an Axis-II personality disorder and/or a substance use disorder, received 100, 200, 300, and 400 mg in an ascending sequence, with intervening placebo doses.Subjects participated 2-3 days per week over 4-6 weeks. Due to cognitive side effects at 300 mg, two subjects only completed through the 200 mg dose. Topiramate produced an inverted U-shaped dose response curve, with increases in aggression peaking at 200 mg and a modest decrease at 400 mg. Statistical analysis revealed a polynomial trend for dose (p=0.001). The observed inverted U-shaped function in aggressive responding is consistent with non-human aggression studies of GABA-A modulators. Acute topiramate doses >400 mg may have anti-aggressive effects, but dose levels in the 200-300 mg range may produce increases in aggression and side effects.

Cognitive disorders associated with epilepsy: diagnosis and treatment

INTRODUCTION

Cognitive disorders are common in patients with epilepsy. Their aetiology is multifactorial, being affected by the type and location of the epileptogenic lesion, epileptic syndrome, type of seizures, age of onset, frequency and severity. Timely diagnosis and treatment can help to reduce their impact on the patient's quality of life.

RESULTS

The most significant cognitive deficits are associated with focal epilepsy, although some, usually mild, neuropsychological disorders can be found in idiopathic generalized epilepsy. The use of antiepileptic drugs (AEDs) can cause additional neuropsychological disorders that are of particular concern in learning-age children and elderly patients with cognitive disorders before the start of treatment. Recent studies have raised the concern that the use of some AEDs during pregnancy may cause cognitive disorders in the child exposed to them in utero. Cognitive disorders can also present as a complication of surgery for refractory epilepsy. Some risk factors for significant memory loss after surgery for temporal lobe epilepsy have been described. They include intervention in the dominant hemisphere, good preoperative function and poor functional reserve in the contralateral hippocampus.

CONCLUSIONS

The heterogeneity of different types of epilepsy makes case-control studies difficult; however, thanks to the growing interest in the neuropsychological deficits associated with epilepsy, we now know some factors that could lead to the appearance of these disorders and their prognosis. Special care must be taken to detect cognitive side effects associated with AEDs, which seem to be more common with classic than with new AEDs, and in those patients receiving polytherapy. Neuropsychological assessment should be routinely performed before epilepsy surgery to predict possible postsurgical cognitive deficits.

Antiepileptic drugs and psychopathology of epilepsy: an update

Anti-epileptic drugs (AEDs) continue to be the mainstay of epilepsy treatment, but the benefits of seizure control need to be weighed carefully against possible adverse effects, which can include behavioral problems and psychiatric disorders. In this paper, the associations between AEDs and psychosis, depression and behavioral changes are reviewed. The concept of forced normalization and its clinical counterpart, alternative psychosis, are also discussed. Depression seems to be linked with AEDs potentiating GABAergic neurotransmission in patients with limbic system abnormalities such as hippocampal sclerosis. Psychoses have been described as associated with several of the new AEDs, and they are often seen in a setting in which previously refractory patients suddenly become seizure-free. In general terms, the use of AEDs in monotherapy, adopting slow titration schedules and low doses when possible, can significantly reduce the occurrence of behavioral adverse effects. A previous history of psychiatric disorder or a familial predisposition are important risk factors and should be always considered when choosing the appropriate AED.

The aspects and mechanisms of cognitive alterations in epilepsy: the role of antiepileptic medications

Epilepsy is a major health problem. Several studies suggest a significant influence of epilepsy and its treatment on dynamic and functional properties of brain activity. Epilepsy can adversely affect mental development, cognition, and behavior. Epileptic patients may experience reduced intelligence, attention, and problems in memory, language, and frontal executive functions. Neuropsychological, functional, and quantitative neuroimaging studies revealed that epilepsy affect the brain as a whole. Mechanisms of epilepsy-related cognitive dysfunction are poorly delineated. Cognitive deficits with epilepsy may be transient, persistent, or progressive. Transient disruption of cognitive encoding processes may occur with paroxysmal focal or generalized epileptic discharges, whereas epileptogenesis-related neuronal plasticity, reorganization, sprouting, and impairment of cellular metabolism are fundamental determinants for progressive cognitive deterioration. Also antiepileptic drugs (AEDs) have differential, reversible, and sometimes cumulative cognitive adverse consequences. AEDs not only reduce neuronal irritability but also may impair neuronal excitability, neurotransmitter release, enzymes, and factors critical for information processing and memory. The present article serves as an overview of recent studies in adult and childhood epilepsy literatures present in PubMed that highlighted cognitive evaluation in epilepsy field (publications till 2008 were checked). We also checked the reference lists of the retrieved studies for additional reports of relevant studies, in addition to our experience in this field. Our search revealed that although the aspects of cognitive dysfunction, risk factors, and consequences have been explored in many studies; however, the mechanisms of contribution of epilepsy-related variables, including AEDs, to patients' cognition are largely unexplored. In this review, we discussed the differential effect of AEDs in mature and immature brains and the known mechanisms underlying epilepsy and AEDs adverse effects on cognition. The nature, timing, course, and mechanisms of cognitive alteration with epilepsy and its medications are of considerable clinical and research implications.

Altered language processing in autosomal dominant partial epilepsy with auditory features

BACKGROUND

Autosomal dominant partial epilepsy with auditory features (ADPEAF) is an idiopathic focal epilepsy syndrome with auditory symptoms or receptive aphasia as major ictal manifestations, frequently associated with mutations in the leucine-rich, glioma inactivated 1 (LGI1) gene. Although affected subjects do not have structural abnormalities detected on routine MRI, a lateral temporal malformation was identified through high resolution MRI in one family. We attempted to replicate this finding and to assess auditory and language processing in ADPEAF using fMRI and magnetoencephalography (MEG).

METHODS

We studied 17 subjects (10 affected mutation carriers, 3 unaffected carriers, 4 noncarriers) in 7 ADPEAF families, each of which had a different LGI1 mutation. Subjects underwent high-resolution structural MRI, fMRI with an auditory description decision task (ADDT) and a tone discrimination task, and MEG. A control group comprising 26 volunteers was also included.

RESULTS

We found no evidence of structural abnormalities in any of the 17 subjects. On fMRI with ADDT, subjects with epilepsy had significantly less activation than controls. On MEG with auditory stimuli, peak 2 auditory evoked field latency was significantly delayed in affected individuals compared to controls.

CONCLUSIONS

These findings do not support the previous report of a lateral temporal malformation in autosomal dominant partial epilepsy with auditory features (ADPEAF). However, our fMRI and magnetoencephalography data suggest that individuals with ADPEAF have functional impairment in language processing.

Patient-reported cognitive side effects of antiepileptic drugs: predictors and comparison of all commonly used antiepileptic drugs

Subjective cognitive side effects (CSEs) are common in patients taking antiepileptic drugs (AEDs). The objective of this study was to predict which patients are at risk for CSEs, and compare the CSE profiles of all commonly used AEDs. In this nonrandomized retrospective study, medical records of 1694 adult outpatients with epilepsy seen at our center over a 5-year period who had taken one or more AEDs were examined. Non-AED predictors of CSEs were investigated, and rates of AED-related CSEs were compared in 1189 patients (546 on monotherapy) newly started on an AED at our center. The average rate of AED-related intolerable CSEs (leading to dosage change or discontinuation) was 12.8%. On multivariate analysis, no significant non-AED predictors of CSEs were found. Significantly more intolerable CSEs were attributed to topiramate (21.5% of 130 patients) than to most other AEDs, including carbamazepine (9.9%), gabapentin (7.3%), levetiracetam (10.4%), lamotrigine (8.9%), oxcarbazepine (11.6%), and valproate (8.3%). CSE rates with zonisamide (14.9%) were significantly higher than those for gabapentin and lamotrigine. After exclusion of CSEs during the first 8 weeks of therapy, rates of CSEs were lower, but relative differences remained unchanged. In monotherapy, significantly more intolerable CSEs occurred with topiramate (11.1% of 18 patients) than with carbamazepine or valproate, and both phenytoin and zonisamide were associated with more CSEs than valproate. From this study, it can be concluded that intolerable patient-reported CSEs are most common with topiramate, followed by zonisamide, phenytoin, and oxcarbazepine. They are least likely to be reported with gabapentin, valproate, lamotrigine, carbamazepine, and levetiracetam.

Topiramate monotherapy in the treatment of newly or recently diagnosed epilepsy

BACKGROUND

The efficacy of topiramate (TPM) as an adjunctive treatment for epilepsy has been established in placebo-controlled clinical trials. Clinical trials of antiepileptic monotherapy usually evaluate low and high doses of study drug or compare study drug with another active agent.

OBJECTIVE

This article reviews available evidence for the use of TPM as monotherapy in patients with newly or recently diagnosed epilepsy.

METHODS

A search of MEDLINE, EMBASE, BIOSIS, SCISEARCH, and the Cochrane Database of Systematic Reviews (all years) for reports of controlled trials of TPM monotherapy in patients with recently diagnosed (within the previous 3 years) epilepsy was conducted in January 2008 using the terms topiramate, epilepsy, newly diagnosed, recently diagnosed, and monotherapy. Identified trials were included in the review if they were published in peer-reviewed journals and enrolled > or = 20 patients.

RESULTS

Three randomized, double-blind, controlled trials met the criteria for inclusion in the review. In a comparison of TPM 50 and 500 mg/d, the higher dose was associated with significantly greater freedom from seizures at 6 months compared with the lower dose (54% vs 39%, respectively; P = 0.02). The time to first seizure was significantly associated with mean plasma TPM concentrations (P = 0.015). In a comparison of TPM 50 and 400 mg/d, the time to first seizure was significantly longer with the higher dose compared with the lower dose (P<0.001, Kaplan-Meier analysis), and the probability of 12-month seizure freedom was significantly higher (76% vs 59%, respectively; P = 0.001). Again, the time to first seizure was significantly associated with mean plasma TPM concentrations (P = 0.029). In a comparative study of TPM 100 and 200 mg/d, carbamazepine 600 mg/d, and valproate 1250 mg/d, there was no significant difference in rates of 6-month seizure freedom with TPM 100 and 200 mg/d (49% and 44%, respectively), carbamazepine (44%), and valproate (44%). Adverse events in the 3 studies were similar between TPM dose groups, although the incidence generally increased with increasing doses, occurred early in treatment, and decreased with prolonged therapy. In a pooled analysis of the 3 trials, the most commonly occurring adverse events during dose titration were paresthesia (25%), fatigue (16%), dizziness (13%), somnolence (13%), and nausea (10%); the most frequent adverse events during maintenance therapy were headache (20%), decreased appetite (11%), and weight loss (11%).

CONCLUSION

In the 3 studies reviewed, TPM monotherapy was effective and generally well tolerated in patients with newly diagnosed epilepsy.

Divalproex sodium extended-release for the prophylaxis of migraine headache in adolescents: results of a stand-alone, long-term open-label safety study

OBJECTIVE

The objective of this long-term open-label study in adolescents was to assess the safety and tolerability of divalproex sodium extended-release in the prophylaxis of migraine headaches.

BACKGROUND

Two formulations of divalproex sodium have demonstrated efficacy in the prevention of migraine headaches in adults. However, no medications are currently approved for this indication in adolescents, and long-term safety data on agents for migraine prevention are lacking for this younger population. Therefore, the current study was conducted to assess the long-term safety and tolerability of divalproex extended-release in adolescents with migraine headaches.

METHODS

This was a 12-month, phase 3, open-label, multicenter study of adolescents aged 12 to 17 years with migraine headaches diagnosed by International Headache Society criteria. Divalproex sodium extended-release was initiated at 500 mg/day for 15 days then increased to 1000 mg daily, with subsequent adjustments permitted within a dosing range of 250-1000 mg daily. Study visits were conducted at days 1 and 15 and months 1, 2, 3, 6, 9, and 12. Safety was evaluated by adverse event collection, laboratory assessments, physical and neurological examinations, vital signs, electrocardiograms, the Udvalg for Kliniske Undersøgelser Side Effect Rating Scale, the Wechsler Abbreviated Scale of Intelligence, and the Behavioral Assessment Scale for Children. Efficacy was evaluated by following the number of migraine headache days reported in subjects' headache diaries over sequential 4-week intervals for the duration of the trial.

RESULTS

A total of 241 subjects were enrolled and treated. The most frequently reported adverse events were nausea (19%), vomiting (18%), weight gain (12%), nasopharyngitis (11%), migraine (10%), and upper respiratory tract infection (10%). Ten (4%) subjects experienced serious adverse events, and 40 (17%) subjects discontinued because of an adverse event. Increases in ammonia levels were observed. No other clinically significant changes were observed in laboratory values, vital signs, rating scales, or electrocardiograms. Median 4-week migraine headache days decreased 75% between the first and the fourth months of the study (from 4.0 to 1.0) and remained at or below this level for the remainder of the study.

CONCLUSIONS

In this long-term open-label study of adolescents with migraine, the safety and tolerability profile of divalproex sodium extended-release was consistent with findings from previous trials in adults, as well as 2 studies recently completed in adolescents. In general, divalproex sodium extended-release was well-tolerated in adolescents with migraine.

Comparative cognitive effects of levetiracetam and topiramate in intractable epilepsy

AIM

Anti-epileptic drugs (AED) may cause cognitive impairment. Because intractable epilepsy (IE) represents a distinct group, the purpose of the present study was to study the comparative cognitive effects of the two efficacious AED, levetiracetam (LEV) and topiramate (TPM), on IE.

METHODS

This was a non-randomized, blinded cognitive assessment and parallel design. The cognitive effects of LEV and TPM on 79 demographically comparable patients with IE were assessed at baseline (T1) and after 1 year of treatment (T2) using the Cognitive Abilities Screening Instrument.

RESULTS

Forty patients took TPM and 39 took LEV. At T1, seizure frequency, number of AED, and epilepsy duration were not significantly different. There were no significant differences in cognition between the two groups at T1 or T2. T2 orientation scores were lower than T1 scores in the TPM group (P < 0.05). In the TPM subgroup with T1 cognitive abnormalities, T2 scores for recent memory improved (P < 0.05).

CONCLUSION

For patients with IE, LEV might preserve cognition, TPM's effects for patients with baseline cognitive abnormalities are worth observation.

The safety and tolerability of galantamine in patients with epilepsy and memory difficulties

Individuals with epilepsy commonly experience memory loss. We investigated the safety and tolerability of galantamine in treatment of memory loss in a pilot study of 28 patients with epilepsy, randomly assigned to galantamine (n=13) or placebo (n=15) and followed for a total of 12 weeks. Participants underwent blinded memory assessment at baseline and 12 weeks (Selective Reminding Test, 7/24 Spatial Recall). One participant in the galantamine group had a suspected recurrence of brain neoplasm and increased seizures; all other participants receiving galantamine showed no increase in seizure activity during the trial. Patients in both groups reported mild, tolerable side effects (headache, appetite suppression), with no difference between groups. No significant differences were observed on the memory measures when both groups were retested at Week 12. Galantamine appears to be safe and tolerable in patients with epilepsy. Further studies with larger samples and comparison with other cholinesterase inhibitors should be considered.

Language disturbances as a side effect of prophylactic treatment of migraine

BACKGROUND

Language disturbances have been previously described as word-finding difficulties in epileptic patients. These disturbances have been recently reported in migraineurs in treatment with topiramate but they have never been defined and assessed in these patients with the aid of neuropsychological testing.

OBJECTIVE

To verify the occurrence of language disturbances as a side effect of topiramate treatment in episodic and chronic migraine patients.

METHODS

Language disturbances were recorded on the basis of spontaneous reports of 30 migraine patients treated with topiramate and 2 control groups (20 patients treated with other prophylactic drugs and 20 patients without prophylactic treatment) and were explored with neuropsychological tests. Psychiatric comorbidity was assessed using Zung Anxiety and Depression Scales.

RESULTS

Language disturbances were referred by 26.7% (n=8) of patients during topiramate treatment but by none of the patients in the 2 control groups. All patients in the topiramate group had a worse performance on all tests compared to patients of the 2 control groups. Moreover, in the topiramate group, patients with referred language disturbances had higher scores for all neuropsychological test variables, indicative of a worse performance. Some language functions (Trail Making Tests A and B) seemed to be influenced by the concomitant presence of psychiatric comorbidities, particularly anxiety and depression.

CONCLUSION

It can be hypothesized that a disorder such as migraine, which involves numerous cortical and subcortical circuits implicated in the transmission and behavioral and emotional processing of pain, represents a facilitated substrate for the occurrence of language disturbances due to topiramate. This could be the expression of a more generalized impairment of cognitive processing. These aspects should be investigated in prospective studies involving larger migraine patient samples.

Topiramate for the treatment of chronic corneal pain

PURPOSE

To explore the option of using anticonvulsant drugs to modulate pain from corneal erosions.

METHODS

N.M. is a 28-year-old woman with posttraumatic recurrent corneal erosions treated with bandage contact lenses, Muro-128, topical ketorolac, doxycycline, stromal micropuncture, and laser epithelial keratomileusis over the course of 4 years. Because of persistent episodes of corneal pain, she was prescribed topiramate.

RESULTS

Before starting topiramate therapy, N.M. had experienced 3-4 awakenings at night because of pain and 5-6 episodes of spontaneous tearing and pain during the day. She started topiramate at 25 mg orally 4 times a day without significant change in her symptoms. After 1 week, the dose was escalated to 50 mg orally 4 times a day, and within 1 day, she experienced 0-1 awakenings at night. She had approximately 2-3 episodes of pain and tearing during the day. The dose was escalated to 100 mg orally 4 times a day. At that dose, the patient continued to have pain relief but complained of nausea. The patient's topiramate was weaned off to determine whether her symptom relief was caused by the medication or improvement in her condition. Once off the topiramate, N.M.'s nausea resolved but her corneal symptoms returned at the same frequency as before the initiation of topiramate. Therefore, she was restarted on topiramate 50 mg orally 4 times a day with rapid onset of improvement in her symptoms.

CONCLUSIONS

Anticonvulsants such as topiramate may be effective in the management of pain caused by recurrent corneal erosions.

The impact of prophylactic treatment on post-traumatic epilepsy after severe traumatic brain injury

AIM

To assess the incidence of late post-traumatic epilepsy (PTE) in patients with very severe traumatic brain injury (TBI) who either received or did not receive anti-epileptic prophylactic treatment.

METHODS

Two populations were studied: 55 patients retrospectively and 82 subjects prospectively.

RESULTS

Ten patients (18%) in the first population showed late PTE. Although the incidence was lower in patients who did not receive prophylactic treatment, the difference between the treated and the non-treated group was not statistically significant. Sixty-nine patients in the second group (84%) had prophylactic treatment. Twenty-seven patients (39%) suffered from late PTE during the 2-year follow-up period and 17 of them (63%) showed EEG epileptic abnormalities. No patient who did not receive preventive therapy suffered from late PTE during the observation period.

CONCLUSIONS

Due to the negative cognitive effects of anti-epileptic drugs, the preliminary results are of considerable interest for the rehabilitation of patients with very severe TBI.

[Anticonvulsant mood stabilizers in the treatment of behavioral and psychological symptoms of dementia (BPSD)]

INTRODUCTION

Dementia, besides the dominant cognitive disorders that define it, is associated with behavioral disturbances, the consequences of which are, on various levels, a determining factor for the handling of these patients. The treatment of behavioral and psychological symptoms is essential and although, to date, no therapeutic solution is satisfactory, it is necessary to look for an alternative to the neuroleptics usually employed, which raise real problems of tolerance in this geriatric population.

BACKGROUND

For several years, anticonvulsants, among which some have shown mood stabilizing activity, have been the object of research in this indication. The purpose of this review of the literature is to assess the interest and the limits of anticonvulsant mood stabilizers (carbamazepine, valproic acid, gabapentin, lamotrigine, topiramate, oxcarbazepine) in the treatment of the so-called "noncognitive" symptoms of dementia. Their mechanism of action in mood disorders is not well known, but it would appear to be via the modulation of glutamate-mediated excitatory synaptic transmission and gamma-aminobutyric acid (GABA)-mediated inhibitory synaptic transmission that anticonvulsants might reduce behavioral symptoms in demented patients.

METHODS

The method employed in this work was a systematic bibliographic review, in which only the double-blind placebo-controlled studies or the clinically detailed enough open-labelled studies using validated scales were retained.

RESULTS

Among these medications, only carbamazepine demonstrated its efficacy in behavioral and psychological symptoms of dementia (BPSD) in controlled studies, notably that of Tariot et al. [J Am Geriatr Soc 42 (1994) 1160-1166 and Am J Psychiatry 155 (1998) 54-61] and Olin et al. [Am J Geriatr Psychiatry 9 (2001) 400-405], but with significant adverse events (sedation, hyponatremia, cardiac toxicity), particularly in the elderly and, being a strong enzymatic inducer, with a high likelihood of drug-drug interactions. Valproic acid showed some interesting results in BPSD within a large number of open studies and case reports. However, among the five controlled studies that have been published [Curr Ther Res 62 (2001) 51-67; Am J Geriatr Psychiatry 9 (2001) 58-66; Int J Geriatr Psychiatry 17 (2002) 579-585; Curr Alzheimer Res 2 (2005) 553-558 and Am J Geraitr Psychiatry 13 (2005) 942-945], none confirmed its efficacy on these symptoms. Regarding its tolerability in the geriatric population, no notable major side effect was reported (haematologic and hepatic effects are not more frequent than in the general population), except possible excessive sedation. Moreover, it appears that valproic acid could have neuroprotective effects, even if the contrary has been observed in a recent study. More studies need to be (and are being) conducted, notably on the interest of valproic acid in prophylaxis of BPSD. Gabapentin seems to be worthwhile and well tolerated in this indication, but no controlled study has been conducted to prove its efficacy, even if a quite important number of case reports and open studies have shown encouraging results. Concerning lamotrigine, which may potentially induce severe cutaneous side effects when administered with valproic acid, this drug has shown its efficacy in bipolar disorders and two recent case reports seem to indicate some interest in BPSD. Furthermore, lamotrigine appears to have neuroprotective effects. Although topiramate has shown interesting results in one open study in BPSD, its use in demented patients cannot be recommended because of its deleterious effect on cognitive functions. Oxcarbazepine, theoretically, could be an alternative to carbamazepine, which is, as aforesaid, the only anticonvulsant that proved its interest in BPSD. However, no clinical study has yet been published to support this hypothesis. This drug is better tolerated than carbamazepine, but induces severe and more frequent hyponatremia.

DISCUSSION AND CONCLUSION

Finally, although we all know that antipsychotics should no longer be prescribed in the elderly, the treatment of behavioral and psychological symptoms of dementia remains a difficult problem, considering the lack of a real alternative to these medications. Anticonvulsant mood stabilizers are an interesting solution but none of them, other than carbamazepine, which did, but which is not better tolerated than the usual drugs in this population - was able to prove its efficacy in this indication. Among these medications, valproic acid, gabapentin and lamotrigine should be studied further, and the neuroprotective effect of some of them is an interesting route for research.

Changes in brain activation during working memory and facial recognition tasks in patients with bipolar disorder with Lamotrigine monotherapy

Verbal working memory and emotional self-regulation are impaired in Bipolar Disorder (BD). Our aim was to investigate the effect of Lamotrigine (LTG), which is effective in the clinical management of BD, on the neural circuits subserving working memory and emotional processing. Functional Magnetic Resonance Imaging data from 12 stable BD patients was used to detect LTG-induced changes as the differences in brain activity between drug-free and post-LTG monotherapy conditions during a verbal working memory (N-back sequential letter task) and an angry facial affect recognition task. For both tasks, LGT monotherapy compared to baseline was associated with increased activation mostly within the prefrontal cortex and cingulate gyrus, in regions normally engaged in verbal working memory and emotional processing. Therefore, LTG monotherapy in BD patients may enhance cortical function within neural circuits involved in memory and emotional self-regulation.

Psychiatric aspects of epilepsy

Patients who have epilepsy face many challenges resulting from their illness and have frequent psychiatric comorbidities. Recognition of these disorders is increasing and is having a positive impact on patients' quality of life. Recent recommendations about a new classification system for psychiatric disorders related specifically to epilepsy and based on the relationship of symptoms to seizures, antiepileptic medications, and EEG changes should further research and treatment. Especially insofar psychiatric syndromes specific to epilepsy can be identified, correlation of clinical phenomena with relatively well-understood pathophysiology in epilepsy will allow advances in the understanding of psychiatric illness. This progress should move the treatment of patients who have epilepsy toward a comprehensive biopsychosocial model that focuses on the whole person rather than simply on the disease process.

Neurocognitive costs and benefits of psychotropic medications in older adults

Psychotropic medications are widely used in older adults and may cause neurocognitive deficits. Older adults are at increased risk of developing adverse effects because of age-related pharmacodynamic and pharmacokinetic changes. This article provides a comprehensive review of the undesirable, and at times beneficial, effects of psychotropic medications. The review covers a wide range of medications that impair executive function, memory, and attention, as well as a much smaller group of medications that lead to improved neurocognitive function. Some of the most commonly used psychotropic medications in older adults, namely, antidepressants, sedatives, and hypnotics, are among the drugs that most consistently lead to cognitive impairments. Medications with anticholinergic properties almost invariably lead to neurocognitive dysfunction, despite symptom improvement. The neurocognitive costs and benefits of psychiatric medications should be considered in the context of disease treatment in older adults.

Lamotrigine therapy in elderly patients with epilepsy, bipolar disorder or dementia

INTRODUCTION

In spite of circumstances that precipitate high use of anticonvulsants in geriatric populations, there is a paucity of data on the use of antiepileptic drugs in elderly patients with psychiatric and neurological disorders.

METHODS

Reports of lamotrigine therapy in elderly patients with epilepsy, bipolar disorder (BD), or dementia were identified by conducting an electronic search of major publication databases. Abstracts and presentations from professional meetings were searched as were the bibliographies of relevant articles.

RESULTS

Fourteen reports were identified, and included well-controlled prospective trials, retrospective analyses, and case reports of lamotrigine treatment. Controlled trials in elderly patients with epilepsy demonstrate efficacy and tolerability comparable to gabapentin. Improvement in bipolar depressive symptoms, improvement in core manic symptoms, and delay in mood relapse was reported in geriatric patients with BD. Preliminary case studies in patients with dementia note improvement in cognition and symptoms of agitation and depression.

CONCLUSION

Review of the available literature suggests lamotrigine is effective and well tolerated in elderly patients with epilepsy and relatively well-tolerated and may be effective in delaying mood relapse, particularly in the depressive pole, in patients with BD. While very limited literature suggests that lamotrigine may be effective and relatively well-tolerated in patients with dementia, further studies are needed.

Effect of open-label lamotrigine as monotherapy and adjunctive therapy on the self-assessed cognitive function scores of patients with bipolar I disorder

Cognitive deficits in patients with bipolar disorder are likely to impair occupational and social functioning. In a post hoc analysis of data from a prospective, open-label study of lamotrigine in 1175 patients 13 years or older with bipolar I disorder, changes in the self-rated cognitive function scores of patients receiving lamotrigine as monotherapy or as adjunctive therapy were evaluated. Lamotrigine was given for 12 weeks, with a target dosage of 200 mg/d. Cognitive function was assessed at baseline and week 12 with the self-rated Medical Outcomes Study Cognitive (MOS-Cog) Scale. Mean MOS-Cog scores improved significantly from baseline in the overall group (+8.4 +/- 22.55 points, P < 0.0001) and in subgroups of patients receiving and not receiving concomitant valproate, antidepressants, or antipsychotics. Patients receiving lamotrigine and not receiving concomitant antipsychotics, however, exhibited a small but significantly greater degree of improvement than patients who were receiving concomitant antipsychotics (adjusted mean difference = 4.05; 95% confidence interval, 1.30-6.81; P = 0.0039). Statistically significant improvement was seen in patient subgroups with a depressive (mean change from baseline, 8.8 +/- 21.97; P < 0.0001) or a manic (mean change from baseline, 7.5 +/- 22.62; P = 0.0007) index episode. Improvements in MOS-Cog scores significantly correlated with improvement in both depressive (correlation coefficient, -0.339; P < 0.0001) and manic (correlation coefficient, -0.151; P < 0.0001) symptoms. Overall, self-rated cognitive function scores improved during open-label lamotrigine therapy in patients with bipolar I disorder whether or not they were receiving concomitant valproate, antidepressants, or antipsychotics. Additional research is needed to explore the clinical relevance of these findings.

The Effects on Cognitive Function and Behavioral Problems of Topiramate Compared to Carbamazepine as Monotherapy for Children with Benign Rolandic Epilepsy

PURPOSE

To evaluate the cognitive and behavioral effects of topiramate (TPM) versus carbamazepine (CBZ) using efficacious doses of each drug as monotherapy for children with benign rolandic epilepsy.

METHODS

A multicenter, randomized, open-label, observer-blinded, parallel-group clinical trial was conducted. TPM was introduced at a dose of 12.5 mg/day with the minimum target dose of 50 mg/day in patients <30 kg and 75 mg/day in patients >30 kg over 4 weeks. CBZ was started at a dose of 10 mg/kg/day with the minimum target dose of 20 mg/kg/day over 4 weeks. Additional individual escalation was allowed up to a maximum target dose. The primary study end point was change on a neuropsychological test battery after 28 weeks of treatment.

RESULTS

Neuropsychological data were available for 88 patients (45 patients for TPM and 43 patients for CBZ). Of the cognitive variables measured, arithmetic showed significant worsening in TPM (p = 0.037). An additional test, for maze, also showed a significantly greater improvement for CBZ (p = 0.026). Of behavioral variables, no significant changes were found but the scores had a negative trend for the TPM. When 30 patients on the minimum target dose for TPM were compared to 40 patients treated with minimum target CBZ, there was no significant worsening of cognitive and behavioral effects in the TPM.

CONCLUSION

The pattern of neuropsychometric changes with TPM seemed to be slightly worse overall than CBZ. However, outcome with the minimum target dose did not differ significantly in comparisons between the treatment groups.

Comparative retention rates and long-term tolerability of new antiepileptic drugs

OBJECTIVE

Retention rates of five new anti-epileptic medications (AEDs) were compared in order to evaluate their long-term tolerability and efficacy.

METHOD

We acquired the retention data on levetiracetam (LEV), lamotrigine (LTG), oxcarbazepine (OXC), topiramate (TPM), and zonisamide (ZNS) from the electronic database. The data included patient's age, gender, seizure type, current and previous medications, dosage, main reasons for discontinuation, and duration of therapy. The retention rates of these AEDs were evaluated at 4, 12, 24, 52, and 104 weeks.

RESULTS

A total of 828 new AED exposures were obtained (LEV=196, LTG=251, OXC=97, TPM=156, ZNS=128) from patients with partial or generalized epilepsy. At 2 years, retention rate was highest with LTG (74.1%), followed by ZNS (60.2%), OXC (58.8%), LEV (53.6%), and TPM (44.2%). When these AEDs were discontinued, it was mainly due to inefficacy (29.5%) and sedating side-effects (20.5%), and commonly within 6 months into therapy. Several important AED specific side-effects leading to discontinuation were identified, including behavioral or irritability from LEV, rash from LTG and OXC, nausea from OXC and ZNS, hyponatremia from OXC, and kidney stones from TPM and ZNS.

CONCLUSION

Comparing retention rates of new AEDs can provide useful insight into their tolerability and efficacy. This study showed highest retention rate with LTG, which was significantly different from ZNS (p=0.0025), LEV (p<0.0001), OXC (p=0.0024), and TPM (p<0.0001). Beside ineffectiveness, other leading causes of discontinuation were adverse behavioral effects with LEV, rash with LTG and OXC, and sedation for TPM and ZNS.

Topiramate effects on the EEG and alertness in healthy volunteers: a different profile of antiepileptic drug neurotoxicity

OBJECTIVE

Previous quantitative EEG (QEEG) studies of carbamazepine (CBZ), oxcarbazepine (OXC), and phenytoin (PHT) revealed a pattern of EEG slowing and an increase in drowsiness on the awake maintenance task (AMT). EEG slowing has been shown to correlate with negative effects on cognitive tests. Topiramate (TPM) is a novel AED with relatively large negative effects on cognitive function. We tested the hypothesis that TPM would induce significant slowing of EEG background rhythms and an increase in AMT drowsiness.

METHODS

Forty healthy volunteers were randomized to TPM, gabapentin (GBP), or placebo. Doses were escalated as tolerated to a maximum of 400mg/day for TPM or 3600 mg/day for GBP, over a 10-week period, followed by a minimum 2-week plateau period. Volunteers underwent an EEG, cognitive tests, and the AMT prior to starting an AED and again 12 weeks later. The EEG was captured using a structured recording protocol and quantified using the fast Fourier transform. Four target measures were derived from the averaged occipital electrodes (peak frequency of the dominant posterior rhythm, median frequency, percentage theta, and percentage delta). Test-retest changes for all measures were scored against similar test-retest distributions previously obtained from untreated healthy volunteers.

RESULTS

TPM produced no significant change in any of the four target EEG measures or on the AMT, even though several target cognitive tests revealed moderate or greater negative effects. There were also no significant changes in the placebo group. GBP slowed the peak and median frequency EEG measures and increased the percentage of theta and delta activity. Neither TPM, GBP, nor placebo caused a significant increase in drowsiness on the AMT.

CONCLUSIONS

TPM has a unique neurotoxicity profile. It has no effect on EEG background measures or on the AMT, but induces moderate to large negative changes in many cognitive test scores. This profile differs from those of CBZ, OXC, PHT, and GBP.