Attention changes in epilepsy patients following 3-month topiramate or valproate treatment revealed by event-related potential

Inhibitory dysfunction may cause prospective memory impairment in temporal lobe epilepsy (TLE) patients: an event-related potential study

Introduction

Prospective memory (PM) is the ability to remember future intentions, and PM function is closely related to independence in daily life, particularly in patients with temporal lobe epilepsy (TLE). As PM involves various cognitive components of attention, working memory, inhibition and other executive functions, this study investigated how TLE may affect PM components and the underlying neural mechanisms.

Methods

Sixty-four subjects were recruited, including 20 refractory TLE patients, 18 well-controlled TLE patients and 26 age-matched healthy controls. A set of neuropsychological tests was administered to assess specific brain functions. An event-related potential (ERP) task was used to further explore how PM and its components would be differentially affected in the two TLE types.

Results

Our findings revealed that: (1) refractory TLE patients scored lower than the healthy controls in the digit span, Verbal Fluency Test and Symbol Digit Modalities Test; (2) refractory TLE patients exhibited impaired PM performance and reduced prospective positivity amplitudes over the frontal, central and parietal regions in ERP experiments when compared to the healthy controls; and (3) decreased P3 amplitudes in the nogo trials were observed over the frontal-central sites in refractory but not in well-controlled TLE patients.

Discussion

To our knowledge, this is the first ERP study on PM that has specifically identified PM impairment in refractory but not in well-controlled TLE patients. Our finding of double dissociation in PM components suggests that inhibition dysfunction may be the main reason for PM deficit in refractory TLE patients. The present results have clinical implications for neuropsychological rehabilitation in TLE patients.

Comparative analysis of acoustic therapies for tinnitus treatment based on auditory event-related potentials

Introduction

So far, Auditory Event-Related Potential (AERP) features have been used to characterize neural activity of patients with tinnitus. However, these EEG patterns could be used to evaluate tinnitus evolution as well. The aim of the present study is to propose a methodology based on AERPs to evaluate the effectiveness of four acoustic therapies for tinnitus treatment.

Methods

The acoustic therapies were: (1) Tinnitus Retraining Therapy (TRT), (2) Auditory Discrimination Therapy (ADT), (3) Therapy for Enriched Acoustic Environment (TEAE), and (4) Binaural Beats Therapy (BBT). In addition, relaxing music was included as a placebo for both: tinnitus sufferers and healthy individuals. To meet this aim, 103 participants were recruited, 53% were females and 47% were males. All the participants were treated for 8 weeks with one of these five sounds, which were moreover tuned in accordance with the acoustic features of their tinnitus (if applied) and hearing loss. They were electroencephalographically monitored before and after their acoustic therapy, and wherefrom AERPs were estimated. The sound effect of acoustic therapies was evaluated by examining the area under the curve of those AERPs. Two parameters were obtained: (1) amplitude and (2) topographical distribution.

Results

The findings of the investigation showed that after an 8-week treatment, TRT and ADT, respectively achieved significant neurophysiological changes over somatosensory and occipital regions. On one hand, TRT increased the tinnitus perception. On the other hand, ADT redirected the tinnitus attention, what in turn diminished the tinnitus perception. Tinnitus handicapped inventory outcomes verified these neurophysiological findings, revealing that 31% of patients in each group reported that TRT increased tinnitus perception, but ADT diminished it.

Discussion

Tinnitus has been identified as a multifactorial condition highly associated with hearing loss, age, sex, marital status, education, and even, employment. However, no conclusive evidence has been found yet. In this study, a significant (but low) correlation was found between tinnitus intensity and right ear hearing loss, left ear hearing loss, heart rate, area under the curve of AERPs, and acoustic therapy. This study raises the possibility to assign acoustic therapies by neurophysiological response of patient.

Effect of long-term administration of clonazepam, carbamazepine, and valproate on cognitive, psychological, and personality changes in adult epilepsy: a case–control study

Background

Epilepsy can be treated with antiepileptic drugs (AEDs) which may have psychiatric and behavioral side effects. Additionally, the availability of new AEDs has increased, and our understanding of variability to combinations of several AEDs has evolved. Based on the treatment outcomes of carbamazepine, valproate, and clonazepam, this study aims to compare the cognitive function, personality, and psychological issues associated with these drugs and evaluate seizure-related factors related to them. Only 139 participants were included. Clonazepam was used as an add-on antiepileptic drug. Participants were categorized into five groups: group 1, carbamazepine; group 2, valproate; group 3, carbamazepine and clonazepam; group 4, valproate and clonazepam; and group 5, epileptic patients without AED. All participants were assessed using the Wechsler Adult Intelligence Scale (WAIS), Structured Interview for the Five-Factor Personality Model (SIFFM), Hamilton Anxiety and Depression Rating Scale, and Minnesota Multiphasic Personality Inventory-2 (MMPI-2).

Results

In the WAIS, group 1 had the worst mean of verbal intelligence quotient (IQ). Moreover, group 3 was more vulnerable in symptomatic response in all subscales of MMPI-2 except the masculinity–femininity subscale and a high percentage in moderate severity of anxiety and depression in the Hamilton scales.

Conclusions

The use of clonazepam and carbamazepine might increase the incidence of behavioral problems especially increased severity of anxiety and depression and decreased performance IQ compared with either clonazepam or carbamazepine alone. Moreover, patients with carbamazepine treatment might have more personality changes and lowered verbal IQ than others.

Auditory and Visual P300 Responses in Early Cognitive Assessment of Children and Adolescents with Epilepsy

Background:

The event-related potential P300 has been suggested to be valuable in the assessment of cognitive dysfunctions. Not a great deal of neurophysiological assessment has been performed at early stages in patients with epilepsy involving visual and auditory P300 measures.

Aims and Objectives:

This study aimed to assess the cognitive status in patients with epilepsy earlier by visual and auditory P300 and to find their correlation with various risk factors.

Materials and Methods:

P300 was recorded in 60 children with epilepsy in the age-group of 5–18 years and 60 age- and sex-matched controls by a rare-frequent (oddball) paradigm. Mean auditory and visual P300 latencies and amplitudes were compared among patients with epilepsy and controls and among patients with generalized and focal epilepsy by unpaired t-test. Pearson’s correlation coefficient test was computed for studying the correlation between risk factors and P300 responses. A value of P < 0.05 was considered statistically significant.

Results:

Statistically significant delay in P300 latencies and reduction in amplitudes (both visual and auditory) was found in patients with epilepsy as compared to controls and also among patients with generalized and focal epilepsy. In generalized epilepsy, both visual and auditory P300 revealed significant delay, whereas only auditory P300 delay was found in focal form. No significant correlation was obtained with risk factors. No significant difference was found in P300 responses among patients with and without antiepileptic treatment.

Conclusion:

Visual and auditory P300 latencies have an important role in the evaluation of early cognitive dysfunctions in children with epilepsy. P300 potentials are not influenced by antiepileptic treatment, whereas the type of epilepsy alters them

Effects of Levetiracetam Compared to Valproate on Cognitive Functions of Patients with Epilepsy

OBJECTIVE

This study compared the effect of levetiracetam (LEV) as monotherapy to sodium valproate (VPA) as monotherapy on cognitive functions in patients with epilepsy.

METHODS

This was a comparative prospective study on 50 patients with newly diagnosed epilepsy started on antiseizure medications. Patients were selected from the neurology-outpatient clinics at Minia University Hospital, Minia, Egypt. They were divided into two groups: group treated with LEV and group treated with VPA. All patients were subjected to cognitive function assessment using reaction-time tests, trail-making tests, and Wisconsin card-sorting test before treatment and 3 months after treatment.

RESULTS

Both groups of patients showed reduction in seizure frequency. However, patients on LEV showed significant improvement in measured cognitive functions 3 months after starting treatment, while patients in the VPA group showed significant impairment in measured cognitive functions 3 months after starting treatment.

CONCLUSION

Both groups of patients showed reduction in seizure frequency. However, patients on LEV showed significant improvement in measured cognitive functions 3 months after starting treatment, while patients in the VPA group showed significant impairment in measured cognitive functions 3 months after starting treatment.

The P300 Event-Related Potential Component and Cognitive Impairment in Epilepsy: A Systematic Review and Meta-analysis

Background: Epilepsy is one of the most prevalent chronic brain diseases worldwide and is often accompanied by cognitive impairment. Event-related potentials (ERPs) are an objectively non-invasive approach for studying information processing and cognitive functions in the brain. The P300 is an important and extensively explored late component of ERPs that has been widely applied to assess cognitive function in epilepsy in previous studies. However, consistent conclusions have not yet been reached for various reasons.

Objective: We conducted a comprehensive systematic review and meta-analysis of P300-related studies to assess the latency and amplitude of the P300 in epileptic patients.

Methods: PubMed, EMBASE, and Cochrane Library databases were systematically searched for eligible studies. The standard mean difference (SMD) and the 95% confidence interval (CI) were calculated as the effect size of the P300 component.

Results: The main results of the present meta-analysis indicated that epileptic patients have a longer P300 latency and a lower P300 amplitude than controls. Subgroup analysis based on age group demonstrated that these differences can be observed in both children and adult patients compared with healthy controls. In addition, the P300 latency was longer in patients with the five main types of epileptic seizures than in controls.

Conclusion: This study revealed that epileptic patients have abnormalities in the P300 component, which may reflect deficits in cognitive function. Thus, the P300 may be a potential objective approach for evaluating cognitive function in epileptic patients.

Evaluating the mediating role of executive functions for antiepileptic drugs' effects on IQ in children and adolescents with epilepsy

Several studies suggest that antiepileptic drug (AED) treatment may permanently or reversibly affect intelligence (intelligence quotient [IQ]) in children and adolescents with epilepsy. Since AED treatment preferentially affects attention and executive functions, we evaluated the potentially mediating effect of executive functions in regard to the adverse effects of drug treatment on intelligence. In a retrospective observational study, 178 children and adolescents with refractory and mostly localization-related epilepsies were evaluated in regard to the interrelation of IQ (Wechsler Intelligence Scale for Children [WISC III] short-form), executive functions (EpiTrack-Junior®, a cognitive AED screening test), and drug treatment (drug load). The results indicate that a low IQ was evident in 23%, impaired executive functions in 59% of the patients. Executive functions correlated to IQ (r = 0.60) and the symbol digits and picture arrangement subtests (R² = 0.46) in particular. Odds ratios for impaired executive functions compared to being off drug (33% impaired) increased from 2.0 with one drug (53% impaired) to 9.5 (83% impaired) with at least three drugs. A mediation analysis revealed that drug dependent differences in executive functions mediate the negative effect of the AED load on intelligence. Hence, executive functions appear to link adverse cognitive side effects of AED treatment to intelligence. Considering Catell's two factor model of intelligence, AEDs preferentially affect the aspects of fluid intelligence. The overall impact of AED on intelligence appears mild. It may become relevant, however, when drug-induced impairments persist over longer time intervals during sensitive developmental phases. This issue needs to be addressed in future longitudinal studies.

Evaluation of cognitive functions in migraineurs treated with topiramate

Topiramate for the treatment of migraine prophylaxis may cause side effects such as cognitive dysfunction. We aimed to investigate the topiramate's efficacy in migraineours and effect on cognitive functions. 24 migraine patients (Group 1) and 24 healthy participants (Group 2) were included. In both groups event-related potentials P300 Latency, Amplitude and N200 Latency, Amplitude's were evaluated. Topiramate treatment was ordered to group 1. Two months after treatment, the same parameters were evaluated. Monthly number of attacks, painful days, analgesic-triptan use and VAS scores were compared before and 2 months after treatment. Evaluation between group 1 and group 2 showed no difference. Group1's before and after treatment values were compared; all parameters after treatment were statistically significantly better. Group 1's number of attacks in a month, the number of painful days in a month, VAS score, the number of analgesic use, the number of triptan use had all decreased after treatment. 100 mg topiramate was effective in the treatment of migraine. However, electrophysiological studies showed that cognitive functions are also affected adversely.

Application of the P300 Event-Related Potential in the Diagnosis of Epilepsy Disorder: A Review

Epilepsy is one of the most serious chronical neurological disorders, affecting more than 50 million people worldwide. It can be defined as a spectrum disorder, and patients with epilepsy possess abnormalities in cognitive functions. A number of factors can cause cognitive dysfunctions in epileptic syndromes, including etiology, the age of onset, type of seizure and severity, duration, and antiepileptic drugs. Event-related potentials (ERPs) are very useful clinical and research instruments to evaluate cognitive function in patients with neuropsychiatry disorders. Event-related potentials directly reflect cortical neuronal activity and provide a particular level of temporal resolution. Among various ERP components, the P300 is the most important component for assessing cognitive processes such as attention, working memory, and concentration. Numerous studies have reported the abnormalities in amplitude or latency of P300 component of ERP in epileptic patients, and these abnormalities are indicative of cognitive dysfunction. Therefore, the purpose of this review is to consolidate the existing literature in connection with the use of P300 in epileptic patients.

Influence of valproate on language functions in children with epilepsy

The aim of the current study was to assess the influences of valproate (VPA) on the language functions in newly diagnosed pediatric patients with epilepsy. We reviewed medical records of 53 newly diagnosed patients with epilepsy, who were being treated with VPA monotherapy (n=53; 22 male patients and 31 female patients). The subjects underwent standardized language tests, at least twice, before and after the initiation of VPA. The standardized language tests used were The Test of Language Problem Solving Abilities, a Korean version of The Expressive/Receptive Language Function Test, and the Urimal Test of Articulation and Phonology. Since all the patients analyzed spoke Korean as their first language, we used Korean language tests to reduce the bias within the data. All the language parameters of the Test of Language Problem Solving Abilities slightly improved after the initiation of VPA in the 53 pediatric patients with epilepsy (mean age: 11.6±3.2years), but only "prediction" was statistically significant (determining cause, 14.9±5.1 to 15.5±4.3; making inference, 16.1±5.8 to 16.9±5.6; prediction, 11.1±4.9 to 11.9±4.2; total score of TOPS, 42.0±14.4 to 44.2±12.5). The patients treated with VPA also exhibited a small extension in mean length of utterance in words (MLU-w) when responding, but this was not statistically significant (determining cause, 5.4±2.0 to 5.7±1.6; making inference, 5.8±2.2 to 6.0±1.8; prediction, 5.9±2.5 to 5.9±2.1; total, 5.7±2.1 to 5.9±1.7). The administration of VPA led to a slight, but not statistically significant, improvement in the receptive language function (range: 144.7±41.1 to 148.2±39.7). Finally, there were no statistically significant changes in the percentage of articulation performance after taking VPA. Therefore, our data suggested that VPA did not have negative impact on the language function, but rather slightly improved problem-solving abilities.

Electrophysiological Correlates of Change Detection during Delayed Matching Task: A Comparison of Different References

Detecting the changed information between memory representation and incoming sensory inputs is a fundamental cognitive ability. By offering the promise of excellent temporal resolution, event-related potential (ERP) technique has served as a primary tool for studying this process with reference of the linked mastoid (LM). However, given that LM may distort the ERP signals, it is still undetermined whether LM is the best reference choice. The goal of the current study was to systematically compare LM, reference electrode standardization technique (REST) and average reference (AR) for assessing the ERP correlates of change detection during a delayed matching task. Colored shapes were adopted as materials while both the task-relevant shape feature and -irrelevant color feature could be changed. The results of the ERP amplitude showed that both of the task-relevant and -conjunction feature changes elicited significantly more positive posterior P2 in REST and AR, but not in LM. Besides, significantly increased N270 was observed in task-relevant and -conjunction feature changes in both the REST and LM, but in the conjunction feature change in AR. Only the REST-obtained N270 revealed a significant increment in task-irrelevant feature change, which was compatible with the delayed behavioral performance. Statistical parametric scalp mapping (SPSM) results showed a left posterior distribution for AR, an anterior distribution for LM, and both the anterior and left posterior distributions for REST. These results indicate that different types of references may provide distinct cognitive interpretations. Interestingly, only the SPSM of REST was consistent with previous fMRI findings. Combined with the evidence of simulation studies and the current observations, we take the REST-based results as the objective one, and recommend using REST technology in the future ERP data analysis.

Comparative behavioral and neurochemical analysis of phenytoin and valproate treatment on epilepsy induced learning and memory deficit: Search for add on therapy

Our previous work demonstrated, chronic epilepsy affects learning and memory of rodents along with peculiar neurochemical changes in discrete brain parts. Most commonly used antiepileptic drugs (phenytoin and sodium valproate) also worsen learning and memory in the patients with epilepsy. Therefore this study was designed to carry out comparison of behavioral and neurochemical changes with phenytoin and sodium valproate treatment in pentylenetetrazole-kindling induced learning and memory deficit to devise add on therapy for this menace. For the experimental epilepsy, animals were kindled using PTZ (35 mg/kg; i.p., at 48 ± 2 h intervals) and successful kindled animals were involved in the study. These kindled animals were treated with saline, phenytoin (30 mg/kg/day, i.p.) and sodium valproate (300 mg/kg/day, i.p.) for 20 days. These animals were challenged with PTZ challenging dose (35 mg/kg) on day 5, 10, 15 and 20 to evaluate the effect on seizure severity score on different days. Effect on learning and memory was evaluated using elevated plus maze and passive shock avoidance paradigm. On day 20, after behavioral evaluations, animals were sacrificed to analyze glutamate, GABA, norepinephrine, dopamine, serotonin, total nitrite level and acetylcholinesterase level in cortex and hippocampus. Behavioral evaluations suggested that phenytoin and sodium valproate treatment significantly reduced seizure severity in the kindled animals, while sodium valproate treatment controls seizures with least memory deficit in comparison to phenytoin. Neurochemical findings revealed that elevated cortical acetylcholinesterase level could be one of the responsible factors leading to memory deficit in phenytoin treated animals. However sodium valproate treatment reduced cortical acetylcholinesterase level and had least debilitating consequences on memory deficit. Therefore, attenuation of elevated AChE activity can be one of add-on approach for management of memory deficit associated with conventional AEDs.

The cognitive impact of antiepileptic drugs

Effective treatment of epilepsy depends on medication compliance across a lifetime, and studies indicate that drug tolerability is a significant limiting factor in medication maintenance. Available antiepileptic drugs (AEDs) have the potential to exert detrimental effects on cognitive function and therefore compromise patient wellbeing. On the other hand, some agents may serve to enhance cognitive function. In this review paper, we highlight the range of effects on cognition linked to a variety of newer and older AEDs, encompassing key alterations in both specific executive abilities and broader neuropsychological functions. Importantly, the data reviewed suggest that the effects exerted by an AED could vary depending on both patient characteristics and drug-related variables. However, there are considerable difficulties in evaluating the available evidence. Many studies have failed to investigate the influence of patient and treatment variables on cognitive functioning. Other difficulties include variation across studies in relation to design, treatment group and assessment tools, poor reporting of methodology and poor specification of the cognitive abilities assessed. Focused and rigorous experimental designs including a range of cognitive measures assessing more precisely defined abilities are needed to fill the gaps in our knowledge and follow up reported patterns in the literature. Longitudinal studies are needed to improve our understanding of the influence of factors such as age, tolerance and the stability of cognitive effects. Future trials comparing the effects of commonly prescribed agents across patient subgroups will offer critical insight into the role of patient characteristics in determining the cognitive impact of particular AEDs.

Cognitive function of idiopathic childhood epilepsy

Most children with epilepsy are of normal intelligence. However, a significant subset will have temporary or permanent cognitive impairment. Factors that affect cognitive function are myriad and include the underlying neuropathology of the epilepsy, seizures, epileptiform discharges, psychosocial problems, age at seizure onset, duration of epilepsy, and side effects associated with antiepileptic drugs. This review article discusses cognitive function in children with idiopathic epilepsy and the effects of antiepileptic drugs on cognitive function in children.

Electrophysiological and auditory behavioral evaluation of individuals with left temporal lobe epilepsy

The purpose of this study was to determine the repercussions of left temporal lobe epilepsy (TLE) for subjects with left mesial temporal sclerosis (LMTS) in relation to the behavioral test-Dichotic Digits Test (DDT), event-related potential (P300), and to compare the two temporal lobes in terms of P300 latency and amplitude. We studied 12 subjects with LMTS and 12 control subjects without LMTS. Relationships between P300 latency and P300 amplitude at sites C3A1,C3A2,C4A1, and C4A2, together with DDT results, were studied in inter-and intra-group analyses. On the DDT, subjects with LMTS performed poorly in comparison to controls. This difference was statistically significant for both ears. The P300 was absent in 6 individuals with LMTS. Regarding P300 latency and amplitude, as a group, LMTS subjects presented trend toward greater P300 latency and lower P300 amplitude at all positions in relation to controls, difference being statistically significant for C3A1 and C4A2. However, it was not possible to determine laterality effect of P300 between affected and unaffected hemispheres.