Behavioural effects of the new anticonvulsants

Levetiracetam in adult patients with and without learning disability: focus on behavioral adverse effects

Optimal antiepileptic drug treatment in patients with learning disability (LD) represents a particular challenge. These patients are often unable to report toxicity, and side effects may manifest as behavioral problems. The aim of this open study was to compare efficacy and tolerability of levetiracetam (LEV) in patients with LD and those without LD. One hundred eighty-four consecutive adult patients who received LEV were followed for an average of 8.1 months. Fifty-six patients (30%) had LD. Thirty-nine percent of patients with refractory epilepsy (37% with and 40% without LD) had > 50% seizure reduction. Significantly more behavioral side effects (23% vs 10%) and a tendency toward less reported somatic central nervous side effects were found in the LD group. We conclude that LEV is equally effective and well tolerated in both patients with LD and patients without LD. However, behavioral problems are more frequent in patients with LD, whereas the tendency toward seizure increase is not enhanced.

Mood effects of antiepileptic drugs

This article reviews our knowledge about a specific subgroup of chronic CNS-related side effects of antiepileptic drugs (AED) treatment, i.e., the effects of AEDs on mood. In line with a recent hypothesis, using the experience of AED treatment in psychiatry, we examined whether mood effects are related to the known anticonvulsant mechanisms of action of the AEDs. Specifically we examined whether AEDs, acting through potentiation of GABAergic neurotransmitter release, have "sedating" effects on mood, whereas AEDs that act through the reduction of excitatory glutamate neurotransmitter release have "activating" effects on mood. The results of this review yield evidence that there are relationships between the known anticonvulsant mechanisms of action of the AEDs and mood effects. Mood effects occur especially when the drugs have a sustained effect on neuronal mechanisms, in particular when the inhibitory or excitatory neurotransmitter release is altered. Drugs with "use-dependent" impact on sodium or calcium channels probably have a more transient impact and do not lead to interictal stable mood effects. Drugs with multiple mechanisms of action seem to combine a favorable efficacy profile with an increased risk of severe mood problems. The quality of the evidence, however, is not conclusive and there are many paradoxical results. One reason for this lack of "fit" may be the use in this review of a simplified classification, based only on the predominant mechanism of action to classify a drug. Only a limited number of AEDs (ethosuximide, tiagabine) are characterized by a single anticonvulsant mechanism of action. Probably more detailed coupling of mechanisms of action (e.g., inspecting the type and route of impact on GABA release) and mood effects may give less confusing results. The use of magnetic resonance imaging techniques such as spectroscopy may provide interesting results.

Behavioral aspects of pediatric epilepsy syndromes

Apart from control of the seizures, two of the most important factors in determining how well a child with epilepsy progresses toward independence are cognition and behavior. The diagnosis of the correct epilepsy syndrome often provides information with regard to probability of good seizure control and intellectual outcome. However, relatively little has been published on the behavioral aspects of the various epilepsy syndromes. In West syndrome there is emerging evidence that early effective treatment might improve outcome in terms of both cognition and behavior. The work on this syndrome in children with tuberous sclerosis has demonstrated an association between temporal lobe tubers and autism. In Dravet syndrome, a variety of psychiatric disorders have been reported, including hyperactivity and autistic features. This is another epilepsy syndrome that tends to be resistant to treatment, implying that the prognosis has to be guarded. The behavioral problems reported with Lennox-Gastaut syndrome also include autistic features, as well as generally sluggish behavior. It is very likely that these characteristics largely reflect the effect of ongoing seizure activity. Autistic features, aggression, and hyperkinesis have been described with Landau-Kleffner syndrome. The behavior may improve dramatically with appropriate medical treatment or after multiple subpial transection. Although the syndrome of benign partial seizures with centrotemporal or rolandic spikes is said to have a very good prognosis, it is becoming increasingly evident that behavioral problems such as concentration difficulties, tempers, hyperactivity, and impulsivity might occur. Juvenile myoclonic epilepsy has been associated with very variable behavioral traits, sometimes with immature personality features and poor social adjustment suggesting frontal lobe dysfunction. Because many of the reports of behavioral disturbance associated with epilepsy syndromes are anecdotal and do not include validated measures of behavior it would be unwise to draw firm conclusions from them at this stage. Carefully conducted prospective studies, paying particular attention to any behavioral improvements that occur with successful treatment of the epilepsy, are required.

Cognitive effects of atypical antipsychotics: focus on bipolar spectrum disorders

Studies examining cognitive dysfunction in bipolar disorder have documented neuropsychologic impairment in some patients. Recollection memory, attention, and visual information processing may be particularly impaired in patients with bipolar illness. Cognitive impairment appears to worsen with illness progression, and may have a significant impact on function. Pharmacotherapy to treat bipolar disorder including lithium, anticonvulsants, antidepressants, and atypical antipsychotics may have varying effects on cognitive functioning. Treatment with atypical antipsychotics has been associated with improvement in various cognitive measures in patients with schizophrenia, and the little data available in patients with bipolar disorder suggest the potential for similar benefits. Studies to determine if current treatments for bipolar disorder can prevent, delay, or even improve cognitive dysfunction are needed.

Aggressive behavior of epilepsy patients in the course of levetiracetam add-on therapy: report of 33 mild to severe cases

Levetiracetam (LEV) was shown to be very efficacious and well tolerated as add-on therapy for refractory epilepsy. Here we report 33 patients with longstanding histories of epilepsy who experienced aggressive episodes during LEV therapy. This corresponds to 3.5% of LEV-treated patients as compared with less than 1% of patients not on LEV. Among these cases, 24 showed only moderate, partly transient irritability, with 10 patients requiring reduction or discontinuation of LEV. More strikingly, 9 patients displayed severe symptoms of aggression with physical violence and, in 2 cases, the need for psychiatric emergency treatment. One patient developed additional psychotic symptoms. We suggest that, specifically in patients with a previous history of aggression, behavioral tolerability of LEV should be carefully monitored.

Selection criteria for the clinical use of the newer antiepileptic drugs

In recent years, several new antiepileptic drugs (AEDs) have been licensed: felbamate, gabapentin, lamotrigine, levetiracetam, oxcarbazepine, tiagabine, topiramate, vigabatrin and zonisamide. These drugs have proven efficacy as add-on therapy in patients with difficult-to-treat partial epilepsy, as 20-50% of patients treated in add-on trials experienced a seizure reduction of >or=50%. Relatively few trials have been conducted to evaluate these drugs as monotherapy for patients with newly diagnosed epilepsy. In the monotherapy trials that have been conducted, the newer drugs were often as efficacious as conventional drugs, and their tolerability was often better. However, the methodology of these trials can be criticised. Because of the relative lack of robust data for the newer agents, the conventional drugs have thus far maintained their status as first-line monotherapy. However, when first-line monotherapy fails, an alternative drug has to be chosen from the available conventional and newer drugs. This article aims to give detailed background information on the newer AEDs in order to enable physicians to make a rational choice from the available drugs for individual patients. Data are provided for the different newer AEDs on mechanisms of action; efficacy in refractory partial epilepsy, newly diagnosed epilepsy in adults and generalised seizure types; adverse effects; pharmacokinetics; and use in special patient categories.

Gabapentin dosing in the treatment of epilepsy

BACKGROUND

Gabapentin is considered a safe and well-tolerated antipileptic drug (AED) with a favorable pharmacokinetic profile and a broad therapeutic index. However, recent studies have used higher doses and faster titration schedules than those used in the pivotal trials that established the efficacy of gabapentin in the treatment of partial seizures.

OBJECTIVE

The purposes of this review were to assess the gabapentin titration and dosing regimens that have been published in peer-reviewed journals, to develop dosing recommendations to maximize antiseizure efficacy without compromising tolerability, and to formulate guidelines for an adequate therapeutic assessment of gabapentin dosage efficacy.

METHODS

In the absence of sufficient placebo-controlled, double-blind studies, a formal evidence-based assessment could not be performed. However, a MEDLINE search using the search terms gabapentin and epilepsy, spanning back to the year 1986, produced numerous published reports from randomized, placebo-controlled and open-label trials, as well as case reports. These were reviewed to assess the range of dosing and titration schedules reported. Reports that employed gabapentin doses and titration schedules were selected for review.

RESULTS

Our review of this literature suggests improved seizure control at higher gabapentin maintenance dosages (< or =3600 mg/d) than are used today in clinical practice (1800 mg/d) without an increase in the incidence of adverse reactions. Most of the patients who received high dosages (eg, 3600 mg/d) or experienced fast titration rates tolerated gabapentin well. Side effects occurred around the onset of dosing and were reported in some studies to be transient.

CONCLUSIONS

Based in the literature here, in most adult patients, gabapentin may be initiated at a dosage of 900 mg/d and titrated to maintenance dosages > or = 3600 mg/d. Children may be treated with gabapentin 23 to 78 mg/kg per day. Based on controlled and open trials, the majority of patients will tolerate gabapentin well enough for an adequate therapeutic assessment. Titration to effect can be accomplished rapidly, if necessary; however, as with other AEDs, optimal seizure control may take months to achieve.

Psychiatric uses of antiepileptic treatments

Antiepileptic drugs (AEDs) possess potent negative or positive psychotropic effects. Clear evidence of benefit exists for valproate, carbamazepine, and lamotrigine in bipolar disorder. Reports of benefit from various AEDs in mood, anxiety, impulse control, and personality disorder are reviewed. Further research is needed to clarify which patients are likely to benefit. Clinicians must closely attend to the ongoing risk/benefit analysis and consider possible iatrogenic worsening of neuropsychiatric symptoms.

Treatment of psychosis, aggression, and irritability in patients with epilepsy

Psychosis, irritability, and aggression in persons with epilepsy are frequently the focus of clinical intervention. These neuropsychiatric symptoms may occur due to the bidirectional relationship between psychosis and epilepsy, in which the potential etiopathogenic mechanisms are believed to be closely related to the seizure disorder itself and also may result from underlying brain injury or behavioral intolerance of antiepileptic or other medication. Epileptic patients are at heightened risk for mood disorders, psychotic disorders, and delerium. The possible lowering of seizure threshold by psychotropic drugs should not contraindicate appropriate use of psychotropic agents, and risk may be minimized by the selection of agents not associated with a relatively high likelihood of altering seizure threshold. Behavioral toxicity of antiepileptic drugs (AEDs) is addressed by selection of alternative agents, and some AEDs appear to possess positive psychotropic effects. The use of antipsychotic, antidepressant, and other psychotropic agents in psychosis, irritability, and aggression in epilepsy is discussed, including dosage ranges, major side effects, and potential interactions between antieplieptic and psychotropic medication.

When is it inappropriate to prescribe psychotropic medication?

Psychotropic medication can be of great value in the treatment of people with epilepsy, but there are situations in which it is not appropriate and other strategies are needed. A number of different strategies, usually not involving psychotropic medication, are required for the behavioural disturbance associated with prodromal mood changes, anxiety-provoking auras, focal discharges, frequent absence seizures, adverse reactions to antiepileptic medication or adverse reactions to antiepileptic drug interactions, difficulties arising from uneven cognitive profiles, reactions to the epilepsy, and causes that are not related to the epilepsy. The first step should always be to determine the cause or causes of behavioural disturbance. A systematic approach to the assessment of the behavioural or psychiatric problems, using a structured diagnostic framework of possible causes, provides the basis for correct diagnosis and management. This systematic approach assists the clinician in deciding when other strategies are preferable to the prescription of psychotropic medication.

Childhood epilepsy in relation to mental handicap and behavioural disorders

Epidemiological studies indicate that there is a high rate of mental retardation and behavioural problems in children with epilepsy. In some cases both the epilepsy and the mental retardation will have a common cause, such as a metabolic disorder or brain trauma. However, in other children, the epilepsy itself may cause either temporary or permanent learning problems. When permanent learning disability can be prevented it is important to treat the epilepsy early and effectively. Children with specific learning difficulties and memory problems can benefit greatly from appropriate management. There are many causes of behavioural disturbance in children with epilepsy. These causes include the epilepsy itself, treatment of the epilepsy, reactions to the epilepsy, associated brain damage/dysfunction and causes that are equally applicable to children who do not have epilepsy. Identifying the cause or causes in each child allows rational management to be provided. Antiepileptic treatment with medication or surgery can either improve the situation or make matters worse. The treatment should be tailored to the needs of the individual child. If surgery is required, there is a strong argument for performing this early in life, both to allow the greatest opportunity for brain plasticity and also to allow the child full benefit from the important developmental and educational years, without the problems that can be associated with the epilepsy. Skilled management of children with epilepsy who have mental retardation and/or behavioural problems can be very rewarding both for the family and for the professionals involved.