Anticonvulsant Drugs, Cognitive Function, and Behavior

Summary: Healthy volunteers as well as patients wih epilepsy were studied for 2 weeks in a double-blind crossover design to determine the effect of anticonvulsant drugs on cognitive function and behavior. The healthy volunteers experienced significant deficits in performance with the four drugs examined, phenytoin, carbamazepine, sodium valproate, and clobazam. The most widespread changes were seen with phenytoin; carbamazepine, sodium valproate, and clobazam did not interfere with tests of memory function. The results of the patients' studies showed that (1) when anticonvulsants are reduced, patients receiving polytherapy improve their cognitive function; (2) patients with high serum levels of anticonvulsant drugs demonstrated more cognitive impairment than those with low levels; (3) when carbamazepine is substituted for another anticonvulsant, cognitive function is improved; and (4) in patients receiving monotherapy, high serum levels are linked to greater cognitive impairment than lower levels and the profile of changes differs between the drugs.     

Effects of oxcarbazepine on cognitive function in children and adolescents with partial seizures

The authors investigated the effect of oxcarbazepine on cognitive function in children and adolescents (6 to younger than 17 years of age) with newly diagnosed partial seizures in an open-label comparison with standard antiepileptic drug therapy (carbamazepine and valproate). No differences in cognitive tests were observed between oxcarbazepine and carbamazepine/valproate over a 6-month treatment period.     

The cognitive effects of oxcarbazepine versus carbamazepine or valproate in newly diagnosed children with partial seizures

OBJECTIVE: To investigate the effect of oxcarbazepine against standard antiepileptic drug therapy (carbamazepine and valproate) on cognitive function in children and adolescents (aged 6 to <17 years) with newly diagnosed partial seizures. METHODS: A multicentre, open-label, randomised, active-control, three-arm, parallel-group, 6-month study. The primary cognitive variable, the Computerized Visual Searching Task (CVST), assessed mental information processing speed and attention. Secondary variables included additional tests assessing psychomotor speed, alertness, memory and learning, and non-verbal intelligence. RESULTS: Of 112 patients randomised, 99 completed the study. The dropout rate was 11.6%; 13 patients discontinued due to adverse events (n=5) or unsatisfactory therapeutic effect (n=8). Mean CVST time decreased in all groups, indicating an improvement of mental processing speed and no cognitive impairment in any treatment group. No statistically significant difference was observed between oxcarbazepine and combined carbamazepine/valproate. Analysis of secondary variables did not show statistically significant differences between oxcarbazepine, carbamazepine and valproate. Analysis of intelligence test results showed that the number of correct answers increased at end point in all groups. The percentage of patients remaining seizure free throughout treatment was comparable across all groups (oxcarbazepine 58%; carbamazepine 46%; valproate 54%; carbamazepine/valproate 50%). The most common adverse events were fatigue and headache for oxcarbazepine, fatigue and rash for carbamazepine, and headache, increased appetite and alopecia for valproate. CONCLUSION: Oxcarbazepine treatment over 6 months does not display any differential effects on cognitive function and intelligence in children and adolescents with newly diagnosed partial seizures relative to standard antiepileptic drug therapy. No impairment in cognitive function was observed in any treatment group over a 6-month period.     

Antiepileptic Drugs, Cognitive Function, and Behavior in Children: Evidence from Recent Studies

Summary: The effects of antiepileptic drugs (AEDs) on cognitive function and behavior in children are reviewed on the basis of published studies. Individual AEDs have been shown to differ–the deleterious effects of phenytoin generally contrasting with the relatively minimal effects of valproate and carbamazepine. Some of the differences between results may be attributed to the psychological tests used and to age differences. However, there appears to be a dissociation between AEDs that affect higher cognitive function, e.g., phenytoin, and those mainly affecting motor function, e.g., carbamazepine, which appears to increase speed of performance. AEDs should be prescribed with care in children with epilepsy, taking account of their differing effects on cognitive function and behavior.     

The influence of mood-normalizing agents on cognitive functions

The influence of lithium, carbamazepine or valproate treatment on the cognitive functions is presented.     

Cognitive Impairment in New Cases of Epilepsy Randomly Assigned to Carbamazepine, Phenytoin and Sodium Valproate

Sixty-four new cases of childhood epilepsy were randomly assigned to either carbamazepine, phenytoin or sodium valproate, and were assessed with cognitive tests before medication and three subsequent times over a year. Carbamazepine in moderate dosage adversely affected memory, but sodium valproate and phenytoin did not.     

The effects of felbamate on appetitive and aversive instrumental learning in adult rats

Antiepileptic medications are the frontline treatment for seizure conditions but are not without cognitive side effects. Previously, our laboratory reported learning deficits in phenytoin-, carbamazepine-, and valproate-treated rats. In the present experiment, the effects of felbamate (FBM) have been compared to water-treated controls (controls) using the same instrumental training tasks employed here. Rats treated with FBM displayed a deficit in acquiring a tone-signaled avoidance response, relative to controls, but this was true only if they had no prior appetitive experience. Terminal avoidance behavior was equivalent to healthy controls. In contrast, the FBM-treated rats showed enhanced acquisition of the avoidance response relative to controls when given the benefit of prior experience in the appetitive condition. Relative to animals treated with phenytoin, carbamazepine, or valproate, FBM-treated rats showed the lowest overall pattern of deficits using these instrumental learning tasks. While FBM treatment has been severely restricted because of rather low risks of serious medical side effects, we suggest that the risks are not substantially higher than those shown to exist for phenytoin, carbamazepine, or valproate. As psychologists, we further suggest that negative cognitive deficits associated with these various drugs, along with their quality-of-life costs, are of relevance in the design of treatment strategies for individuals with seizure disorders.     

Anticonvulsant Drugs and Cognitive Function: A Review of the Literature

Summary: Alterations of cognitive function are separate from disturbances of behavior seen in association with epilepsy. The nature of the cognitive disability may to a certain extent depend on the seizure type. Partial seizures, mainly derived from a temporal lobe focus, impair memory tasks, while generalized seizures seem to have more effect on attentional abilities. A number of studies, reviewed in this paper, suggest that anticonvulsant drugs further impair cognitive function. Maximal impairments are seen in patients receiving polytherapy: rationalization of polytherapy improves cognitive abilities. Studies in children and adults have allowed differentiation of the effects of various commonly used antiepileptic agents. Maximal cognitive deficits are seen with. phenytoin, while phenobarbital and sodium valproate induce moderate disturbances, and carbamazepine seems relatively free from such toxicity. Further research is needed on the interrelationship between types of seizure disorders, types of anticonvulsant medications, and cognitive function.     

Cognitive functions, epileptic syndromes and antiepileptic drugs.

Cognitive function of patients on monotherapy specific for their epileptic syndrome has been studied infrequently. We evaluated 7 patients with symptomatic localised epilepsies (SEL) on phenytoin aged 30 +/- 12 (mean +/- standard deviation) years, 8 with idiopathic generalised epilepsies on sodium valproate aged 18 +/- 4 years, 16 with SEL on carbamazepine aged 28 +/- 11 years, and 35 healthy controls aged 27 +/- 11 years. All subjects were of normal intelligence, educated appropriately to age, and led productive lives in the community. Two of the patients on carbamazepine and one on valproate had less than five partial, absence or myoclonic seizures monthly, the remaining were controlled. Carbamazepine serum concentrations were 12 +/- 5 micrograms/ml, phenytoin were 23 +/- 7, and valproate were 62 +/- 23 (mean +/- sd). Tests included immediate recall and recognition for pictures, Stroop test, delayed recall and recognition of pictures. Patients on phenytoin and valproate performed significantly worse than controls on immediate recall, and patients on carbamazepine performed significantly worse than controls in Stroop test (p < 0.01). The results indicate relatively minor effects of the epileptic syndromes and of phenytoin, carbamazepine and valproate on cognition of patients with controlled epilepsy leading productive lives in the community. We conclude that the cognitive deficit found in chronic epileptic patients on poly-therapeutic drug regimen must be multifactorial, and that future studies need to control for all possible variables in order to achieve meaningful results.     

Anticonvulsant potency and neurotoxicity of valproate alone and in combination with carbamazepine or phenobarbital

Although single drug therapy of epilepsy has been increasingly advocated, patients whose epilepsy is not controlled by monotherapy are commonly treated with more than one antiepileptic drug. In order to investigate the experimental background for antiepileptic drug combinations, the effect of the pharmacodynamic interactions between valproate and carbamazepine and between valproate and phenobarbital on the efficacy/toxicity ratio was studied in mice. All results were expressed in terms of drug concentrations in the brain in order to exclude possible pharmacokinetic interactions from the analysis. Purely additive interactions were found for the anticonvulsant effect when valproate was combined with carbamazepine as well as with phenobarbital. With regard to the neurotoxic effect, however, the interaction was additive between valproate and phenobarbital but infra-additive for valproate and carbamazepine. Thus, in this model, the combination of valproate and phenobarbital has no advantage over each drug alone, but the combination of valproate with carbamazepine has a better efficacy versus toxicity ratio than either valproate alone or carbamazepine alone. Based on these and previous results, there can be experimental evidence in favor of combining certain antiepileptic drugs, but each combination needs to be studied separately.     

Efficacy and tolerability of conversion to monotherapy with lamotrigine compared with valproate and carbamazepine in patients with epilepsy

OBJECTIVE: This randomized, open-label study was designed to compare the efficacy and tolerability of lamotrigine monotherapy with those of valproate and carbamazepine monotherapy in patients with epilepsy whose seizures were uncontrolled on their prestudy antiepileptic drug monotherapy. METHODS: Patients meeting eligibility criteria were randomized 2:1 to lamotrigine:carbamazepine or lamotrigine:valproate. The treatment phase was divided into a 4-week dose-escalation phase (Weeks 1-4), during which lamotrigine, carbamazepine, or valproate was added to patient's prestudy monotherapy; an 8-week add-on phase (Weeks 5-12), during which patients were stabilized on both the study medication and their prestudy antiepileptic therapy; an 8-week withdrawal phase (Weeks 13-20), during which prestudy antiepileptic therapy could be withdrawn if clinically appropriate; and an 8-week monotherapy phase (Weeks 21-28), during which patients could be treated with study medication as monotherapy. RESULTS: The numbers of patients randomized to the carbamazepine and valproate arms of the study were 144 (98 lamotrigine, 46 carbamazepine) and 158 (105 lamotrigine, 53 valproate), respectively. Successful monotherapy sustained for at least 7 weeks was achieved in comparable percentages of patients in the lamotrigine group (56%) and the carbamazepine group (54%) and in more patients in the lamotrigine group (49%) than the valproate group (40%). Among monotherapy completers, the percentage of patients with zero seizures during the monotherapy phase was comparable for lamotrigine (41%) and carbamazepine (30%) and significantly higher (P<0.05) with lamotrigine (32%) than with valproate (11%). No differences between treatments were observed with respect to time to treatment failure or time to first seizure. Lamotrigine was also better tolerated than carbamazepine or valproate. CONCLUSION: Lamotrigine monotherapy was as effective as and better tolerated than carbamazepine or valproate monotherapy in patients whose seizures were uncontrolled on their prestudy antiepileptic drug monotherapy.     

The effects of valproate exposure in utero on behavior and the need for educational support in school-aged children

Children exposed to valproate monotherapy in utero were evaluated with respect to neurological functioning, behavior, and additional educational needs, and the results were compared with those for age- and gender-matched controls exposed to carbamazepine and children with no prenatal exposure to antiepileptic drugs. We identified from the community-based pregnancy registry of Kuopio University Hospital area (1989-2000) all first-born and school-aged children exposed to valproate (N=13). Neurological and neuropsychological assessments were made clinically, and behavioral problems were assessed with the Conners' Teacher Rating Scale (CTRS). Eight children (62%) exposed to valproate and two (15%) each in the carbamazepine-exposed and nonexposed groups (P=0.022) required educational support. Minor dysmorphic features were noted in eight children (62%) exposed to valproate and in three children (23%) each in the carbamazepine-exposed and nonexposed groups. On CTRS, children exposed to valproate received higher scores, indicating behavioral problems. In our small but population-based study, all children exposed to valproate had minor, and some of them major, cognitive or neurological problems. This difference is clearly observed when assessing each child individually, but the many confounding factors explaining at least part of this difference are difficult to control and avoid in clinical practice. Larger studies with a prospective design are needed to confirm these findings.     

丙戊酸钠与卡马西平治疗躁狂发作临床观察

目的：评价丙戊酸钠与卡马西平对锂盐治疗无效的躁狂发作的疗效和副反应。方法：将符合CCMD－2－R躁狂发作诊断标准的5例患者随机分为丙戊酸钠组和卡马西平组,治疗6周。使用Bech-Rafaelsen躁狂量表及临床疗效总评量表的疗效总评评定疗效,用副反应量表及有关实验室检查评定副反应。结果：丙戊酸钠与卡马西平均能有效减轻躁狂症状,疗效相近,丙戊酸钠起效时间迟于卡马西平。丙戊酸钠的副反应主要为肠道反应、震颤等、而卡马西平以共济失调、头晕、嗜睡等多见。结论：丙戊酸钠与卡马西平均可用于锂盐治疗无效的躁狂发作。     

Effects of antiepileptic drugs on attention as assessed by a five-choice serial reaction time task in rats

Patients with epilepsy can have impaired cognitive abilities. Antiepileptic drugs (AEDs) may contribute to the cognitive deficits observed in patients with epilepsy, and have been shown to induce cognitive impairments in healthy individuals. However, there are few systematic data on the effects of AEDs on specific cognitive domains. We have previously evaluated a number of AEDs with respect to their effects on working memory. The purpose of the present study was to evaluate the effects of AEDs on attention as measured by five-choice serial reaction time behavior in nonepileptic rats. The GABA-related AEDs triazolam, phenobarbital, and chlordiazepoxide significantly disrupted performance by increasing errors of omission, whereas tiagabine, valproate, and gabapentin did not. The sodium channel blocker carbamazepine increased errors of omission at relatively high doses, whereas the sodium channel blockers phenytoin, topiramate, and lamotrigine were without significant effect. Levetiracetam had no effect on attention. The disruptions produced by triazolam, phenobarbital, chlordiazepoxide, and carbamazepine were similar in magnitude to the effects of the muscarinic cholinergic receptor antagonist scopolamine. The present results indicate that AEDs can disrupt attention, but there are differences among AEDs in the magnitude of the disruption in nonepileptic rats, with drugs that enhance GABA receptor function producing the most consistent disruption of attention.     

Teratogenicity of antiepileptic drug combinations with special emphasis on epoxidation (of carbamazepine)

A higher rate of congenital anomalies has been found after prenatal exposure to some combinations of antiepileptic drugs than to the separate drugs. In an earlier study a rate of 58% congenital anomalies was found among infants exposed to carbamazepine plus phenobarbitone plus valproate. In this study an attempt was made to determine whether this specific combination of drugs has teratogenic activity due to metabolic interaction. The epidemiological data were analyzed further. The high rate of congenital anomalies after prenatal exposure to this combination could not be explained by the effects of one or two of these drugs only, nor by additional exposure to phenytoin. Assuming that metabolic interaction in the arene oxide pathway resulting in accumulation of epoxide intermediates of antiepileptic drugs could be responsible for teratogenesis, the ratio of carbamazepine to carbamazepine-10, 11-epoxide concentrations in serum was determined in adult patients with epilepsy who were treated with carbamazepine only and with different combinations of phenobarbitone, valproate, and/or phenytoin. For carbamazepine monotherapy the mean ratio was 8.19. For all combinations lower ratios were found, indicating accumulation of carbamazepine-10,11-epoxide. The combination of carbamazepine, phenobarbitone, valproate, and phenytoin showed the lowest ratio (1.94), followed by carbamazepine, valproate, and phenytoin and by carbamazepine, phenobarbitone, and valproate (2.81 and 3.18, respectively). These results give rise to the question of whether the combination of carbamazepine, phenobarbitone, valproate, and/or phenytoin has teratogenic activity by accumulation of carbamazepine-10,11-epoxide or other epoxide intermediates, and stress the need to take metabolic interactions into account when investigating the teratogenic activity of antiepileptic drugs.     

Effects of antiepileptic drugs on attention as assessed by a five-choice serial reaction time task in rats

Patients with epilepsy can have impaired cognitive abilities. Antiepileptic drugs (AEDs) may contribute to the cognitive deficits observed in patients with epilepsy, and have been shown to induce cognitive impairments in healthy individuals. However, there are few systematic data on the effects of AEDs on specific cognitive domains. We have previously evaluated a number of AEDs with respect to their effects on working memory. The purpose of the present study was to evaluate the effects of AEDs on attention as measured by five-choice serial reaction time behavior in nonepileptic rats. The GABA-related AEDs triazolam, phenobarbital, and chlordiazepoxide significantly disrupted performance by increasing errors of omission, whereas tiagabine, valproate, and gabapentin did not. The sodium channel blocker carbamazepine increased errors of omission at relatively high doses, whereas the sodium channel blockers phenytoin, topiramate, and lamotrigine were without significant effect. Levetiracetam had no effect on attention. The disruptions produced by triazolam, phenobarbital, chlordiazepoxide, and carbamazepine were similar in magnitude to the effects of the muscarinic cholinergic receptor antagonist scopolamine. The present results indicate that AEDs can disrupt attention, but there are differences among AEDs in the magnitude of the disruption in nonepileptic rats, with drugs that enhance GABA receptor function producing the most consistent disruption of attention.     

A multicentre comparative trial of sodium valproate and carbamazepine in adult onset epilepsy. Adult EPITEG Collaborative Group.

The long-term efficacy and safety of sodium valproate and carbamazepine in adult outpatients with newly diagnosed primary generalised or partial and secondarily generalised seizures were compared in a randomised, open, multicentre study at 22 neurology outpatient clinics. Patients were randomised to oral sodium valproate (Epilim EC enteric coated 200 mg tablets twice daily, n = 149) or oral carbamazepine (100 mg twice daily increasing to 200 mg twice daily in week 2, n = 151) and followed up for three years. If clinically necessary, dosages were regularly increased until seizures were controlled or toxicity developed. Sodium valproate and carbamazepine controlled both primary generalised and partial seizures equally effectively overall. Significantly more patients on sodium valproate than carbamazepine (126/140 (90%) v 105/141 (75%), p = 0.001) remained on randomised treatment for at least six months. Skin rashes occurred significantly more often in carbamazepine recipients than in sodium valproate recipients (11.2% v 1.7%, p < 0.05) and carbamazepine was associated with a higher withdrawal rate because of adverse events (15% v 5% on sodium valproate) in the first six months of treatment. There was no difference between the drugs in the rate of withdrawal because of poor seizure control at any stage, regardless of seizure type. At the end of the three year trial period, over 70% of the available patients were still on randomised treatment or had recently stopped treatment after achieving full seizure control. Sodium valproate and carbamazepine were both associated with a high degree of overall seizure control regardless of seizure type and both have good long-term tolerability in adult patients with newly diagnosed epilepsy. Recommendations are made for a higher initial dosage regime for sodium valproate in partial seizures.     

Psychiatric and Behavioural Disorders in Children with Epilepsy (ILAE Task Force Report): Adverse cognitive and behavioural effects of antiepileptic drugs in children

The literature was evaluated for cognitive and more general behavioural effects. We distinguished the older antiepileptic drugs (AEDs), from the newer and newest AEDs. The striking finding was the lack of information on children. From the available evidence it would appear that there may be negative cognitive effects with phenobarbital, phenytoin, topiramate and zonisamide, and adverse behavioural effects with phenobarbital, valproate, gabapentin, topiramate, levetiracetam and zonisamide. There is inconclusive data on ethosuximide, clobazam, vigabatrin, felbamate, pregabalin, stiripentol, rufinamide, lacosamide and retigabine. The following drugs appear to be neutral with regard to cognitive effects: valproate, carbamazepine, gabapentin and oxcarbazepine. Carbamazepine appears to be neutral with regard to behavioural effects. Positive cognitive effects have been reported with lamotrigine and levetiracetam. Positive behavioural effects have been reported with lamotrigine. Recommendations are provided.     

Cognitive function and anticonvulsant therapy: effect of monotherapy in epilepsy

Introduction – The effect of antiepileptic drugs (AED) on cognitive function was studied in 87 patients with epilepsy. Material and methods – Group A: (n = 52) started AED treatment (carbamazepine, oxcarbazepine, sodium-valproate, phenobarbital or phenytoin). Group B: (n = 27) had AED monotherapy withdrawn (carbamazepine or sodium-valproate). Group C: (n = 8) was switched from phenytoin to carbamazepine monotherapy. The patients were tested before and 4 months after change of the treatment. Results – In group A the test performances were in general unchanged. Patients who had their drug treatment withdrawn (group B) and the patients who were switched from phenytoin to carbamazepine (group C) improved in single tests. The predominant changes in performance seem to be due to practice effect. Conclusion – Cognitive functions are only minimally influenced by AEDs after short-term treatment whereas there is a slight improvement after discontinuation of long-term administration of carbamazepine and valproate. A lack of practice effect might be the first indicator of a negative effect of AED on cognitive function.     

Use of antiepileptic drugs in the treatment of epilepsy in people with intellectual disability

The main principles of antiepileptic drug treatment of epilepsy in patients with intellectual disability are basically the same as for other patients with epilepsy. However, some specific issues need to be taken into account These are primarily associated with the diagnostic difficulties of epilepsy in this population. In addition, a number of other relevant issues, including the degree and location of brain lesion, the nature of the underlying disease, the higher frequency of difficult-to-treat epilepsies, the additional intellectual impairment caused by inappropriate antiepileptic medication, or by frequent and prolonged seizures, the appropriate use of monotherapy versus rational polytherapy, and the use of broad-spectrum antiepileptic drugs will be discussed in the present paper. Although the goals of treatment are to keep the patient seizure-free and alert while preventing possible mental deterioration, we have to accept compromises between these primary goals in many cases. Some people with epilepsy and intellectual disability are very vulnerable to insidious neurotoxic effects; for example, sedative effects caused by phenobarbital, or cognitive and/or cerebellar dysfunction caused by long-term phenytoin, especially together with other drugs. Because of the adverse effects of phenobarbital and phenytoin, these drugs are no longer recommended as a first-choice drugs when long-term antiepileptic medication is required. In primary generalized tonic-clonic seizures, valproate, oxcarbazepine/carbamazepine and lamotrigine are recommended in this order of preference. The corresponding recommendations are: in typical absences, valproate, ethosuximide and lamotrigine; in atypical absences, valproate and lamotrigine; in juvenile myoclonic epilepsy, valproate, lamotrigine and clobazam; in infantile spasms vigabatrin, ACTH and valproate; in Lennox-Gastaut syndrome, valproate, lamotrigine and vigabatrin; in atonic seizures, valproate and lamotrigine; in simple and complex partial seizures with or without secondary generalization, oxcarbazepine/carbamazepine, valproate/ vigabatrin and lamotrigine; and in status epilepticus lorazepam, diazepam and clonazepam together with phenytoin or fosphenytoin. In cases of poor response to the monotherapy recommended above, the following combinations may be indicated: in primary generalized tonic-clonic epilepsy, valproate and oxcarbazepine/ carbamazepine, or valproate and lamotrigine; in typical absences, valproate and lamotrigine, or valproate and ethosuximide; in juvenile myolonic epilepsy, valproate and lamotrigine, or valproate and clonazepam; and in partial epilepsies, add to the monotherapy one of the following drugs, vigabatrin, lamotrigine, gabapentin, tiagabine, topiramate, zonisamide or clobazam. So far, the order of preference of these new drugs remains undetermined. More data are needed on the efficacy and adverse effects of the new drugs based on controlled studies on patients with intellectual disability and epilepsy.