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

Association between gabapentin use and risk of dementia in adults with chronic pain: A nested case-control study

STUDY OBJECTIVE

To explore the association between gabapentin use and the risk of dementia in patients with chronic pain, considering the rising concerns of dementia in an aging population and the potential cognitive impacts of chronic pain management.

DESIGN

A nested case-control study utilizing data from a longitudinal health insurance database.

SETTING

The study is based on a longitudinal health insurance database spanning 2000-2019 in Taiwan.

PATIENTS

A total of 201,492 patients aged 50 years and older diagnosed with chronic pain between 2001 and 2017 were included. The study focused on individuals with chronic pain, excluding those diagnosed with dementia a year before or after their chronic pain diagnosis.

INTERVENTION

Analysis of gabapentin prescription history was conducted, considering the cumulative dose from the chronic pain diagnosis date to the dementia diagnosis date or equivalent period for controls.

MEASUREMENT

Data included demographics, gabapentin prescription history, and comorbidities. Logistic regression was used to estimate odds ratios for dementia risk.

MAIN RESULTS

No significant difference in the risk of dementia was found between low and high cumulative doses of gabapentin. The adjusted odds ratio for dementia risk associated with gabapentin use was 0.91 (95 % C.I. 0.83-1.01), indicating no substantial increase in risk.

CONCLUSION

Long-term Gabapentin therapy for chronic pain is not associated with a differential risk of dementia across dosage levels, irrespective of age or gender. Further study into its potential cognitive impacts is essential.

Cognitive effect of antiseizure medications in medial temporal lobe epilepsy

BACKGROUND AND PURPOSE

The specific effects of antiseizure medications (ASMs) on cognition are a rich field of study, with many ongoing questions. The aim of this study was to evaluate these effects in a homogeneous group of patients with epilepsy to guide clinicians to choose the most appropriate medications.

METHODS

We retrospectively identified 287 refractory patients with medial temporal lobe epilepsy associated with hippocampal sclerosis. Scores measuring general cognition (global, verbal and performance IQ), working memory, episodic memory, executive functions, and language abilities were correlated with ASM type, number, dosage and generation (old vs. new). We also assessed non-modifiable factors affecting cognition, such as demographics and epilepsy-related factors.

RESULTS

Key parameters were total number of ASMs and specific medications, especially topiramate (TPM) and sodium valproate (VPA). Four cognitive profiles of the ASMs were identified: (i) drugs with an overall detrimental effect on cognition (TPM, VPA); (ii) drugs with negative effects on specific areas: verbal memory and language skills (carbamazepine), and language functions (zonisamide); (iii) drugs affecting a single function in a specific and limited area: visual denomination (oxcarbazepine, lacosamide); and (iv) drugs without documented cognitive side effects. Non-modifiable factors such as age at testing, age at seizure onset, and history of febrile seizures also influenced cognition and were notably influenced by total number of ASMs.

CONCLUSION

We conclude that ASMs significantly impact cognition. Key parameters were total number of ASMs and specific medications, especially TPM and VPA. These results should lead to a reduction in the number of drugs received and the avoidance of medications with unfavorable cognitive profiles.

The effect of gabapentin and pregabalin administration on memory in clinical and preclinical studies: a meta-analysis and systematic review

BACKGROUND

Today, gabapentinoids such as Gabapentin (GBP) and pregabalin (PGB) are widely used as painkillers. This may alter the function of the nervous system; hence their results may include a difference in memory and processes that end in memory formation. This study aims to conclude whether gabapentinoids can alter memory or not by reviewing and analyzing clinical and preclinical studies.

MATERIAL AND METHODS

A comprehensive search was carried out in databases including PUBMED, EMBASE, SCOPUS, and Web of Science. In the included studies, memory was measured as an outcome variable in clinical or preclinical studies.

RESULT

A total of 21 articles (4 clinical, 17 preclinical) were included in the meta-analysis by STATA Software. The results showed that memory changes under the influence of GBP. Both the administrated dosage and the time of administration are important in the final results and latency time of retention. GBP administration in healthy animals increased latency time, whereas if the administration of GBP took place exactly before training, the latency time increased slightly. Short-term administration of PGB in healthy volunteers is accompanied by transient side effects on the CNS. However, the number and homogeneity of the studies were not such that a meta-analysis could be performed on them.

CONCLUSION

Clinical and preclinical studies showed that PGB administration did not confirm its improving memory effect. GBP administration in healthy animals increased latency time and improved memory. Although it depended on the time of administration.

The association of gabapentin initiation and neurocognitive changes in older adults with normal cognition

Background: Gabapentin is increasingly prescribed to older adults, which raises concerns about its potential to cause neurocognitive changes. Therefore, we aimed to examine the association of gabapentin use with neurocognitive changes (i.e., cognitive decline, functional status decline, and motor function change) in older adults. Methods: We conducted a retrospective cohort study using the National Alzheimer's Coordinating Center Uniform Data Set (UDS; September 2005-March 2021 data freeze). From the eligible sample (≥age 65 years), we identified cognitively normal new-users of gabapentin and the visit they initiated gabapentin (i.e., index visit). Initiators were matched to randomly selected nonusers on year of UDS enrollment and visit number from enrollment to index. Cognitive decline was defined as any increase in the Clinical Dementia Rating global score (CDRGLOB) and as a 1-point increase in CDR sum of boxes (CDR-SB). Functional status decline was defined as a 3-point increase in the sum of the Functional Activities Questionnaire (FAQ) and as 0.3-point increase in mean FAQ. Decline in motor function was defined as new clinician reports of gait disorder, falls, and slowness. To mitigate confounding and selection bias, we used joint stabilized inverse probability of treatment weights and stabilized inverse probability of censoring weights. All analyses were conducted comparing index to index+1 and index+2 visits. Results: From the eligible UDS participants (N = 23,059), we included 480 initiators (mean age [SD]: 78.7 [6.9]; male 34.4%); 4,320 nonusers (78.3 [7.0]; 34.4%). Gabapentin initiation was significantly associated with cognitive/functional status decline: worsening CDRGLOB at index+1 visit (odds ratio [95% confidence interval]: 1.55 [1.07, 2.25]); CDR-SB at index+1 visit (1.94 [1.22, 3.09]); and mean of FAQ at index+2 visit (1.78 [1.12, 2.83]). After excluding initiators with extant motor dysfunction (n = 21), we identified 459 initiators (78.7 [6.9]; 34.0%) and 4,131 nonusers (78.2 [6.9]; 34.7%); in this sample, gabapentin initiation was associated with increased falls at the index+2 visit (2.51 [1.19, 5.31]). Conclusion: Gabapentin initiation was significantly associated with deleterious neurocognitive changes among older adults with initially normal cognition. Further studies are needed to examine the risk/benefit of prescribing gabapentin in older adults.

Cognitive reawakening and improved quality of life achieved after discontinuing 16 years of anti-seizure treatment with topiramate

A 42-year-old female patient with epilepsy and a co-morbid migraine suffered from the severe cognitive side effects of topiramate (TPM) for more than 16 years with detrimental consequences for her daily functioning, career, and social interaction. Even a prodromal stage of dementia was suggested, giving rise to fears of developing a neurodegenerative disease. Recently, cognitive monitoring of attention and executive function before and after withdrawal of TPM revealed a significant recovery from the severe negative cognitive side effects of the long-standing and inefficacious antiseizure medication (ASM). Whereas the side effects were reversible after cessation, their consequences for the patient`s biography were permanent. A considerable increase in quality of life, however, was observed without TPM and family members were impressed by the improvements. This case illustrates the potentially severe consequences of negative cognitive side effects which affect daily functioning, career and social life, thus underscoring the importance of being knowledgeable of the potential cognitive risks when prescribing an ASM. Because cognitive side effects may not depend solely on ASM choice and drug load, but also on individual idiosyncratic intolerances, and patients might stay on their treatment for many years, cognitive monitoring is highly recommended.

The impact of perampanel on cognition: A systematic review of studies employing standardized tests in patients with epilepsy

This systematic review was conducted to reveal the cognitive effects of perampanel (PER) as assessed by objective standardized neuropsychological measures in patients with epilepsy. A systematic literature search was performed in PubMed. In addition we cross-checked a list of relevant studies (based on a ProQuest search) provided by Eisai GmbH. Eligibility criteria were (1) group studies reporting the cognitive outcome of treatment with PER in patients with epilepsy (2) which employed objective cognitive tests and (3) were published in English. Of the 56 initially retrieved records, 9 eligible studies were included in the qualitative synthesis. Two studies were based on the very same sample. Altogether the included studies analyzed a total of 241 patients (46% pediatric) with adjunctive PER. All studies were longitudinal with assessments before and after introduction of PER (up to 5 follow-ups and observation intervals of up to 1 year). Two studies were retrospective, 6 lacked a control condition. Neuropsychological assessments varied in extent and test selection. Overall no systematic cognitive deteriorations or improvements after introduction of PER have been reported across the analyzed studies. The only randomized placebo-controlled trial found a transient worsening in attention and speed of memory at the 19-week follow-up, and in addition a late decline in another parameter of attention at the final 52-week follow-up. This systematic review on the objective cognitive effects of PER suggests an overall neutral cognitive profile of PER with no systematic cognitive deteriorations or improvements. More controlled studies on the cognitive effects of PER would be appreciated.

Are ion channels potential therapeutic targets for Parkinson's disease?

Parkinson's disease (PD) is primarily associated with the progressive neurodegeneration of the dopaminergic neurons in the substantia nigra region of the brain. The resulting motor symptoms are managed with the help of dopamine replacement therapies. However, these therapeutics do not prevent the neurodegeneration underlying the disease and therefore lose their effectiveness in managing disease symptoms over time. Thus, there is an urgent need to develop newer therapeutics for the benefit of patients. The release of dopamine and the firing activity of substantia nigra neurons is regulated by several ion channels that act in concert. Dysregulations of these channels cause the aberrant movement of various ions in the intracellular milieu. This eventually leads to disruption of intracellular signalling cascades, alterations in cellular homeostasis, and bioenergetic deficits. Therefore, ion channels play a central role in driving the high vulnerability of dopaminergic neurons to degenerate during PD. Targeting ion channels offers an attractive mechanistic strategy to combat the process of neurodegeneration. In this review, we highlight the evidence pointing to the role of various ion channels in driving the PD processes. In addition, we also discuss the various drugs or compounds that target the ion channels and have shown neuroprotective potential in the in-vitro and in-vivo models of PD. We also discuss the current clinical status of various drugs targeting the ion channels in the context of PD.

Treatment for the Benign Childhood Epilepsy With Centrotemporal Spikes: A Monocentric Study

Background and Purpose: To date, there is no specific treatment guideline for the benign childhood epilepsy with centrotemporal spikes (BECTS). Several countries recommend levetiracetam, carbamazepine, sodium valproate, oxcarbazepine, and lamotrigine as first-line drugs. Nevertheless, some of these drugs are associated with cognitive decline. Available studies that investigated the efficacy of levetiracetam and sodium valproate on BECTS involved small sample sizes. This study aimed to evaluate the efficacy of levetiracetam and sodium valproate on cognition, and to investigate the prognostic factors for BECTS as whole.

Methods: Clinical data and treatment status of all patients with BECTS at Xiangya Hospital, Central South University followed from 2008 to 2013 were analyzed retrospectively. Since electrical status epilepticus in sleep (ESES) has been confirmed to play a role in cognitive deterioration, in order to evaluate the response to drugs and their cognitive effects, we created two groups of patients according to the levels of spike wave index (SWI): group 1; 0–50% SWI and group 2; >50% SWI at the last follow up.

Results: A total of 195 cases were enrolled: 49.7% received monotherapies, 24.1% duotherapies and 27.2% polytherapies. Medications included; levetiracetam plus other drug (s) (75.9%), levetiracetam alone (32.8%), sodium valproate plus other drug (s) (31.3%), and sodium valproate alone (5.1%). After 2 years of treatment and follow up, 71% of the cases had a good seizure outcome, 15.9% had an improvement of SWI, and 91.7% had a normal DQ/IQ. Sodium valproate combined with levetiracetam, and sodium valproate alone correlated with good improvement of SWI, whereas, focal spikes were linked with poor improvement. For both groups (group 1 and group 2): monotherapy, levetiracetam alone, and a normal DQ/IQ at seizure onset correlated with good cognitive outcomes, in contrast, polytherapy, sodium valproate plus other drug (s), levetiracetam plus sodium valproate, an initial SWI of ≥85%, and multifocal spikes were linked to cognitive deterioration.

Conclusions: Monotherapy, particularly levetiracetam seems to be a good first-line therapy which can help in normalizing the electroencephalograph and preventing cognitive decline. Polytherapy, mostly the administration of sodium valproate seems to relate with poor cognition, therefore, it is recommended to avoid it.

Efficacy of Cicuta virosa medicinal preparations against pentylenetetrazole-induced seizures

Epileptic seizures are characterized by imbalanced inhibition-excitation cycle that triggers biochemical alterations responsible for jeopardized neuronal integrity. Conventional antiepileptic drugs (AEDs) have been the mainstay option for treatment and control; however, symptomatic control and potential to exacerbate the seizure condition calls for viable alternative to these chemical agents. In this context, natural product-based therapies have accrued great interest in recent years due to competent disease management potential and lower associated adversities. Cicuta virosa (CV) is one such herbal remedy that is used in traditional system of medicine against myriad of disorders including epilepsy. Homeopathic medicinal preparations (HMPs) of CV were assessed for their efficacy in pentylenetetrazole (PTZ)-induced acute and kindling models of epilepsy. CV HMPs increased the latency and reduced the duration of tonic-clonic phase in acute model while lowering the kindling score in the kindling model that signified their role in modulating GABAergic neurotransmission and potassium conductance. Kindling-induced impairment of cognition, memory, and motor coordination was ameliorated by the CV HMPs that substantiated their efficacy in imparting sustained neuronal fortification. Furthermore, biochemical evaluation showed attenuated oxidative stress load through reduced lipid peroxidation and strengthened free radical scavenging mechanism. Taken together, CV HMPs exhibited promising results in acute and kindling models and must be further assessed through molecular and epigenomic studies.

A prospective pilot study of cognitive impairment and mood in adults with first seizure, new-onset epilepsy, and newly diagnosed epilepsy at time of initial seizure presentation

INTRODUCTION

This is an observational prospective cohort study of cognition and mood in individuals presenting to a tertiary neurology clinic with first unprovoked seizure (FS), new-onset epilepsy (NOE), and newly diagnosed epilepsy (NDE). Our aim was to understand the cognitive profile of these three diagnostic groups at the time of first presentation. Follow-up was obtained to evaluate any association between cognition at presentation and subsequent clinical course.

METHODS

Forty-three participants (age: 18-60 years) were recruited with FS (n = 17), NOE (n = 16), and NDE (n = 10). Clinical details, neuropsychological testing, and screening for mood disorders were obtained at the time of presentation to clinic. Seizure recurrence was evaluated at clinic follow-up at least 6-12 months following the initial presentation.

RESULTS

In all groups, general intelligence (intelligence quotient [IQ]) was consistent with population norms, but more than half of participants (55.8%) were impaired in at least one cognitive domain. The most commonly impaired domain in all diagnostic groups was visuospatial and visuoconstruction suggesting that it may be a sensitive marker of early cognitive impairment. Those with epilepsy (NOE and NDE) at initial presentation were more likely to be impaired than those with FS, particularly on tests of attention, working memory, and processing speed. Seven participants with FS converted to NOE (FSNOE) at follow-up. They were more likely to be impaired on tests of memory than those with FS who did not convert to NOE. On mood screening, 21% of participants scored moderate or severe for depressive symptoms, and 25.6% of participants scored moderate or severe for anxiety symptoms.

DISCUSSION

Cognitive impairment and mood changes are common at first seizure presentation and mirror the pattern seen in chronic epilepsy. This cooccurrence of symptomatology at disease onset prior to prolonged antiepilepsy drug exposure suggests a shared underlying disease mechanism and carries important clinical implications for effective diagnosis and management of epilepsy. Furthermore, early cognitive testing may become a clinical biomarker and enable the prediction of an individual's clinical course.

Cognitive, adaptive, and behavioral effects of adjunctive rufinamide in Lennox-Gastaut syndrome: A prospective observational clinical study

INTRODUCTION

Lennox-Gastaut syndrome (LGS) is a severe pediatric epilepsy syndrome characterized by multiple drug-resistant seizure types. Children with LGS usually experience cognitive regression, and LGS is almost always associated with moderate to severe cognitive impairment. Rufinamide (RFM) was approved by the European Medicines Agency in 2007 for the adjunctive treatment of seizures associated with LGS in patients ≥4 years of age. The primary objective of our study was to assess cognitive, adaptive, and behavior functioning of patients with LGS after 12 months of RFM therapy.

METHODS

This was an observational, multicenter, prospective study involving 16 patients diagnosed with LGS aged between 7 and 58 years (mean = 22 ± 16.3). Fourteen of 16 patients were already on therapy with 3 antiseizure drugs and 2/16 with 4 antiseizure drugs; RFM has been added with 100 mg/week increments up to a dose of 300-2400 mg/day. The participants and their parents underwent a neuropsychological evaluation for the assessment of intellectual, adaptive, and emotional/behavioral functioning (Leiter International Performance Scale-Revised (LEITER-R), Vineland, and Child Behavior CheckList (CBCL), respectively) before the RFM introduction (baseline) and 12 months after the RFM therapy (T2). Physical and neurological examination, electroencephalography (EEG) recording, seizure type and frequency, and adverse reactions were also considered.

RESULTS

After 12 months, the total intelligence quotient (IQ) assessed by LEITER-R did not show statistical significant changes, such as there were no statistically significant changes in adaptive functions, assessed by Vineland. Furthermore, there were no statistically significant changes in internalizing and externalizing problems assessed by CBCL.

CONCLUSION

Adjunctive treatment with RFM did not negatively affect cognitive, adaptive function, and emotional profile in patients with LGS after 1 year of follow-up.

Assessing various sensorimotor and cognitive functions in people with epilepsy is feasible with robotics

BACKGROUND

Epilepsy is a common neurological disorder characterized by recurrent seizures, along with comorbid cognitive and psychosocial impairment. Current gold standards of assessment can quantify cognitive and motor performance, but may not capture all subtleties of behavior. Here, we study the feasibility of assessing various upper limb sensorimotor and cognition functions in people with epilepsy using the Kinarm robotic assessment system. We quantify performance across multiple behavioral domains and additionally consider the possible effects of epilepsy subtype and medication.

METHODS

We recruited individuals with a variety of epilepsy subtypes. Participants performed 8 behavioral tasks that tested motor, cognitive, and sensory domains. We collected data on the same tasks from a group of control participants that had no known neurological impairments. We quantified performance using Task Scores, which provide a composite measure of overall performance on a given task and are adjusted for age, sex, and handedness.

RESULTS

We collected data from 46 individuals with epilepsy and 92 control participants. The assessment was well-tolerated, with no adverse events recorded. Cognitive tasks testing spatial working memory, executive function, and motor response inhibition were the most frequently impaired in the epilepsy cohort, with 33/46 (72%) being outside the normal range on at least one of these tasks. Additionally, 29/46 (63%) were impaired on at least one task testing primarily motor skill, and 14/46 (30%) were impaired on a proprioceptive sensory task. People with either focal epilepsy or generalized epilepsy performed significantly worse on both motor and cognitive tasks than control participants after correcting for multiple comparisons. There were no statistical differences between generalized and focal epilepsy groups on Task Scores. Finally, individuals taking topiramate trended toward having worse performance on a spatial working memory task than other individuals with epilepsy who were not taking topiramate.

CONCLUSIONS

Kinarm robotic assessment is feasible in individuals with epilepsy and is well-tolerated. Our robotic paradigm can detect impairments in various sensorimotor and cognitive functions across the population with epilepsy. Future studies will explore the role of epilepsy subtype and medications.

Pharmaco-fMRI: A Tool to Predict the Response to Antiepileptic Drugs in Epilepsy

Pharmacological treatment with antiepileptic medications (AEDs) in epilepsy is associated with a variety of neurocognitive side effects. However, the mechanisms underlying these side effects, and why certain brain anatomies are more affected still remain poorly understood. Advanced functional magnetic resonance imaging (fMRI) methods, such as pharmaco-fMRI, can investigate medication-related effects on brain activities using task and resting state fMRI and showing reproducible activation and deactivation patterns. This methodological approach has been used successfully to complement neuropsychological studies of AEDs. Here we review pharmaco-fMRI studies in people with epilepsy targeting the most-widely prescribed AEDs. Pharmco-fMRI has advanced our understanding of the impact of AEDs on specific brain networks and thus may provide potential biomarkers to move beyond the current “trial and error” approach when commencing anti-epileptic medication.

Interventions and cognitive functioning in adults with traumatic spinal cord injuries: a systematic review and meta-analysis

AIM

This research synthesized scientific evidence on the impact of interventions for adults with traumatic spinal cord injury on cognition, to understand if current intervention approaches are appropriate in light of the risk of post-injury cognitive impairments.

METHOD

Medline, Central, Embase, Scopus, PsycINFO and PubMed were searched for intervention in persons with SCI assessing cognition pre- and post-intervention. Study quality was completed using the National Institutes of Health quality assessment tools. Results were grouped by type of intervention. The meta-analysis involved calculation of pooled effect sizes for interventions utilizing the same cognitive measure.

RESULTS

Eleven studies of moderate quality discussed drug therapy, transcutaneous tibial nerve stimulation, diet modification and dietary supplements, and inpatient rehabilitation. Some aspects of cognition were negatively affected by drugs while diet modification and supplement use, and transcutaneous tibial nerve stimulation showed no evidence of a difference in cognitive scores when compared with no intervention. Inpatient rehabilitation revealed a small but beneficial effect, when results of seven studies were pooled.

CONCLUSION

Evidence on the effects of interventions on cognitive functioning in patients with traumatic spinal cord injury is sparse and inconclusive, so work in this area is timely. It is valuable to know not only which interventions are effective for improving cognition, but also how other commonly used interventions, intended to treat other injury sequela, can affect cognition. PROSPERO: CRD42018087238.Implications for rehabilitationHistorically, rehabilitation of patients with traumatic spinal cord injury has targeted physical impairments, with little attention to cognition; this research aimed to understand if current interventions are appropriate in light of the risk of patients' cognitive impairments. Evidence on the effects of drug therapy, diet and dietary supplements interventions on cognitive functioning in traumatic spinal cord injury is sparse and inconclusive.Combining multiple inpatient rehabilitation interventions shows a positive but heterogeneous effect on the cognitive functioning; interventions applied earlier show greater gains.A major challenge for clinicians is to select an outcome measure sensitive to change over time, and to relate the results to patients' change in cognitive abilities with intervention applicationResearch to understand the functional effect of spinal cord injury on the widely distributed networks of the central and autonomic nervous systems subserving cognition, is timely.

Impulsiveness as a predictor of topiramate response for cocaine use disorder

BACKGROUND/OBJECTIVES

Topiramate has been studied in the treatment of substance use disorders and is often used off-label in the treatment of other disorders with impaired impulse control. We sought to determine whether impulsiveness could predict topiramate treatment response in individuals with cocaine use disorder (CUD).

METHODS

In a post-hoc analysis of a 12-week, double-blind, randomized, placebo-controlled trial of topiramate for CUD, we examined the relationship between response to treatment and participants' baseline score on the Barrett Impulsiveness Scale (BIS-11). During the original trial, topiramate was titrated up to 300 mg/day over 6 weeks and maintained for 6 weeks. All participants received weekly cognitive behavioral therapy.

RESULTS

Individuals with total BIS-11 scores above the median had 11.2% more cocaine-free days with topiramate versus placebo (Bonferroni corrected p = 0.047). Individuals with first-order factor scores above the median in self-control (Bonferroni corrected p = 0.020) and at or below the median in attention (Bonferroni corrected p = 0.022), and second-order factor scores at or below the median in attentional (Bonferroni corrected p = 0.024) and motor impulsiveness (Bonferroni corrected p = 0.046) were all associated with a greater improvement with topiramate.

DISCUSSION/CONCLUSION

The results indicate an association between higher within-group impulsiveness and response to topiramate for CUD. The subscore findings may suggest a complex interaction between effectiveness and known cognitive side effects. The finding that trait impulsiveness is associated with treatment response is a promising discovery that may help guide treatment for CUD.

SCIENTIFIC SIGNIFICANCE

This analysis suggests a possible endophenotype based on impulsiveness that can predict treatment response to topiramate. (Am J Addict 2019;XX:1-6).

Carbonic anhydrase enzymes: Likely targets for inhalational anesthetics

Inhalational anesthetics such as isoflurane, desflurane and halothane are the mainstay medications for surgical procedures; upon inhalation, they produce anesthesia described as reversible unconsciousness with the features of amnesia, sleep, immobility and analgesia. To date, how they produce anesthesia is unknown. This study proposes that carbonic anhydrase enzymes are likely targets mediating the actions of inhalational anesthetics. Carbonic anhydrase enzymes, commonly expressed in living organisms, utilize carbon dioxide (CO₂) as a substrate and can generate H⁺ and HCO₃^- from CO₂ with a great efficiency. There are remarkable lines of evidence for their likely roles in mediating anesthetic actions. Firstly, carbonic anhydrase enzymes are extensively expressed in the brain and spinal cord, and their importance in the brain activity, especially for the GABA and NMDA receptor signaling pathways, has been demonstrated in numerous studies. According to these studies, they provide HCO₃^- for GABA-A receptor activities and also buffer HCO₃^- excess resulting from NMDA receptor activation. Activation of GABA-A and inhibition of NMDA receptors are associated with the induction of anesthesia by the intravenous general anesthetics propofol and ketamine, respectively. Secondly, the carbonic anhydrase inhibitors topiramate and zonisamide are effectively used in the treatment of epilepsy for decades; their chronic use results in the requirement of increased levels of amobarbital in order to produce anesthesia in the epileptic patients during WADA test. In addition, given that CO₂ is a substrate for these enzymes, their tertiary structure is likely has a hydrophobic pocket suitable for the anesthetic molecules to bind. Inhalational anesthetic molecules, which are lipophilic and inert in nature, have an ability to cross the membranes and inhibit carbonic anhydrases, which might not be accessible by topiramate and zonisamide. Unlike carbonic anhydrase inhibitors, they could bind to the hydrophobic pocket for CO₂ molecules and produce a profound effect called anesthesia. Finally, there is a great deal of similarities between the physiological actions of inhalational anesthetics and carbonic anhydrase inhibitors; moreover well-known side effects of inhalational anesthetics could be associated with the inhibition of carbonic anhydrases. Therefore, this article presents a hypothesis that the anesthetic actions of inhalational anesthetics could be due to their inhibitory effects on the carbonic anhydrases. Investigating this hypothesis might lead to the development of new safer anesthetics, and more importantly it might reveal an endogenous anesthetic pathway, in which the carbonic anhydrase system is a component along with the GABA-A and NMDA receptor systems.

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.

Real-world assessment of treatment with extended-release topiramate (Trokendi XR®) and comparison with previous immediate-release topiramate treatment

AIM

Examine clinical profile of extended-release topiramate (Trokendi XR^®) and compare treatment-emergent adverse events (TEAEs) associated with Trokendi XR versus previous immediate-release topiramate (TPM-IR) treatment.

PATIENTS & METHODS

Pilot retrospective study analyzing data extracted from medical charts of patients ≥6 years of age prescribed Trokendi XR.

RESULTS

Trokendi XR was the most commonly used to prevent migraine. The most common TEAEs recorded during topiramate treatment were cognitive symptoms (word-finding difficulty, attention/concentration difficulty, slowed thinking), paresthesia, gastrointestinal problems and decreased appetite/weight loss. TEAE incidence was significantly (p < 0.001) lower during Trokendi XR versus previous TPM-IR treatment.

CONCLUSION

Trokendi XR use and outcomes in clinical practice were consistent with established profile of topiramate. Results supported the potential for better tolerability of Trokendi XR versus TPM-IR.

Cognitive and Social Outcomes of Epileptic Encephalopathies

The term "epileptic encephalopathy" denotes a disorder in which seizures or frequent interictal discharges exacerbate neurocognitive dysfunction beyond what would be expected on the basis of underlying etiology. However, many underlying causes of epileptic encephalopathy also result in neurocognitive deficits, and it can be challenging to discern to what extent these deficits can be improved with better seizure control. Additionally, as seizures in these conditions are typically refractory, children are often exposed to high doses of multiple antiepileptic drugs which further exacerbate these comorbidities. This review will summarize the neurocognitive and social outcomes in children with various epileptic encephalopathies. Prompt, accurate diagnosis of epilepsy syndrome and etiology allows selection of optimal therapy to maximize seizure control, limiting the impact of ongoing seizures and frequent epileptiform abnormalities on the developing brain. Furthermore, mandatory screening for comorbidities allows early recognition and focused therapy for these commonly associated conditions to maximize neurocognitive outcome.

Comparative effects of chronic administrations of gabapentin, pregabalin and baclofen on rat memory using object recognition test

Memory impairment is one of the greatest concerns when it comes to long-term CNS-affecting drug administration. Drugs like gabapentin, pregabalin and baclofen are administered in a long-term period in conditions such as epilepsy, neuropathic pain, spasticity associated with spinal cord injury or multiple sclerosis. Despite their wide spread use, few data are available on the effects of these drugs on cognitive functions, such as learning memory. In the present study, the effects of long-term administration of gabapentin, pregabalin and baclofen on memory were investigated in a comparative manner. Male Wistar rats received intraperitoneal (i.p.) injection of gabapentin (30 mg/kg), pregabalin (30 mg/kg), baclofen (3 mg/kg), combination of gabapentin/baclofen (30/3 mg/kg) and combination of pregabalin/baclofen (30/3 mg/kg) once a day for 3 weeks respective to their groups. After the end of treatments, rat memories were assessed using the object-recognition task. The discrimination and recognition indices (RI and DI) in the T2 trials were used as the memory indicating factors. The results showed that daily i.p. administrations of pregabalin but not gabapentin or baclofen significantly decreased DI and RI compared to saline group. In combination groups, either gabapentin or pregabalin impaired discrimination between new and familiar objects. Our findings suggested that pregabalin alone or in combination with baclofen significantly caused cognitive deficits.

Topiramate in Migraine Prevention: A 2016 Perspective

BACKGROUND

In evidence-based guidelines published in 2000, topiramate was a third-tier migraine preventive with no scientific evidence of efficacy; recommendation for its use reflected consensus opinion and clinical experience. Its neurostabilizing activity, coupled with its favorable weight profile, made topiramate an attractive alternative to other migraine preventives that caused weight gain. When guidelines for migraine prevention in episodic migraine were published in 2012, topiramate was included as a first-line option based on double-blind, randomized controlled trials involving nearly 3000 patients. The scientific and clinical interest in topiramate has generated a large body of data from randomized controlled trials, meta-analyses, patient registries, cohort studies, and claims data analyses that have more fully characterized its role as a migraine preventive.

AIM

This article will review the profile of topiramate that has emerged out of the past decade of research and clinical use in migraine prophylaxis. It will also address the rationale for extended-release (XR) formulations in optimizing topiramate therapy in migraine.

SUMMARY

Topiramate has activity at multiple molecular targets, which may account for why it is effective in migraine and most other, more specific, anticonvulsants are not. Based on randomized controlled trials, topiramate reduces migraine frequency and acute medication use, improves quality of life, and reduces disability in patients with episodic migraine and in those with chronic migraine with or without medication overuse headache. Its efficacy in chronic migraine is not improved by the addition of propranolol. Topiramate's ability to prevent progression from high-frequency episodic migraine to chronic migraine remains unclear. Consistent with clinicians' perceptions, migraineurs are more sensitive to topiramate-associated side effects than patients with epilepsy. Paresthesia is a common occurrence early in treatment but is rarely cause for terminating topiramate treatment. Cognitive problems occur much less frequently than paresthesia but are more troublesome in terms of treatment discontinuation. Cognitive complaints can often be managed by slowly increasing the topiramate dose in small increments to allow habituation. As with other carbonic anhydrase inhibitors, topiramate has metabolic effects that favor the development of metabolic acidosis and possibly renal stones. Because migraineurs have an increased risk of renal stones independent of topiramate exposure, clinicians should counsel all migraine patients to maintain hydration. Abrupt onset of blurring, other visual disturbances, and/or ocular pain following topiramate's initiation should be evaluated promptly since this may indicate rare but potentially sight-threatening idiosyncratic events. Postmarketing evidence has shown that first-trimester exposure to topiramate monotherapy is associated with increased occurrence of cleft lip with or without cleft palate (Pregnancy Category D). Even though topiramate's long half-life would seemingly support q.d. dosing, randomized controlled migraine trials used b.i.d. administration of immediate-release (IR) topiramate, which has more favorable plasma concentration-time profile (ie, lower peak concentrations and higher trough concentrations) than q.d. IR dosing. Given the sensitivity of migraineurs to topiramate-related adverse events, particularly cognitive effects, pharmacokinetic profiles should be considered when optimizing migraine outcomes. The extended-release (XR) formulations Qudexy^® XR (Upsher-Smith Laboratories) and Trokendi XR^® (Supernus Pharmaceuticals) were specifically designed to achieve the adherence benefits of q.d. dosing but with more favorable (ie, more constant) steady-state plasma concentrations over the 24-hour dosing interval vs IR topiramate b.i.d. Intriguing results from a study in healthy volunteers showed consistently less impairment in neuropsychometric tests of verbal fluency and mental processing speed with an XR topiramate formulation (Trokendi XR) vs IR topiramate b.i.d. These findings suggest a pharmacodynamic effect associated with significantly reducing plasma concentration fluctuation when topiramate absorption is slowed. Results of retrospective studies in migraineurs treated with XR topiramate appear to support a clinically meaningful benefit of XR topiramate vs IR topiramate in terms of significantly fewer cognitive effects, improved adherence, and overall better outcomes of migraine prophylaxis with topiramate.

Pharmaco fMRI: Determining the functional anatomy of the effects of medication

Functional MRI studies have helped to elucidate underlying mechanisms in complex neurological and neuropsychiatric disorders. Disease processes often involve complex large-scale network interactions, extending beyond the presumed main disease focus. Given both the complexity of the clinical phenotype and the underlying dysfunctional brain circuits, so called pharmaco-fMRI (ph-MRI) studies probe pharmacological effects on functional neuro-anatomy, and can help to determine early treatment response, mechanisms of drug efficacy and side effects, and potentially advance CNS drug development. In this review, we discuss recent ph-MRI research in three major neuropsychiatric and neurological disorders and associated network alterations, namely selective serotonin and noradrenergic reuptake inhibitors in affective disorders and emotional processing circuits; antiepileptic drugs in epilepsy and cognitive networks; and stimulants in attention-deficit/hyperactivity disorder and networks of attention control. We conclude that ph-MRI studies show consistent and reproducible changes on disease relevant networks, and prove sensitive to early pharmacological effects on functional anatomy associated with disease. Further CNS drug research and development would benefit greatly from improved disease phenotyping, or biomarkers, using advanced imaging techniques.

Short-term neurocognitive outcomes following anterior temporal lobectomy

Changes in cognitive function are a well established risk of anterior temporal lobectomy (ATL). Deficits in verbal memory are a common postoperative finding, though a small proportion of patients may improve. Postoperative evaluation typically occurs after six to 12months. Patients may benefit from earlier evaluation to identify potential needs; however, the results of a formal neuropsychological assessment at an early postoperative stage are not described in the literature. We compared pre- and postoperative cognitive function for 28 right ATL and 23 left ATL patients using repeated measures ANOVA. Changes in cognitive function were compared to ILAE seizure outcome. The mean time to postoperative neuropsychological testing was 11.1weeks (SD=6.7weeks). There was a side×surgery interaction for the verbal tasks: immediate memory recall (F(1,33)=20.68, p<0.001), short delay recall (F(1,29)=4.99, p=0.03), long delay recall (F(1,33)=10.36, p=0.003), recognition (F(1,33)=5.69, p=0.02), and naming (F(1,37)=15.86, p<0.001). This indicated that the left ATL group had a significant decrement in verbal memory following surgery, while the right ATL group experienced a small but significant improvement. For the right ATL group, there was a positive correlation between ILAE outcome and improvement in immediate recall (r=-0.62, p=0.02) and long delay recall (r=-0.57, p=0.03). There was no similar finding for the left ATL group. This study demonstrates that short-interval follow-up is effective in elucidating postoperative cognitive changes. Right ATL was associated with improvement in verbal memory, while left ATL resulted in a decrement in performance. Improvement in the right ATL group was related to improved seizure outcome. Short-interval follow-up may lend itself to the identification of patients who could benefit from early intervention.

Clinical Utility of the Mig-SCog

BACKGROUND

Mig-SCog is a 9-item questionnaire developed to quantify attack-related cognitive complaints in migraine (M). The items relate to executive function and language, and the total Mig-SCog score is the sum of those scales.

OBJECTIVE

To evaluate the Mig-SCog scores regarding cognitive symptoms during a variety of conditions.

METHODS

We conducted a prospective comparative study of the Mig-SCog scores (1) between migraine and tension-type headache (TTH) patients during a headache; (2) in migraine patients between migraine attacks, non-headache pain and pain-free status; (3) in migraine patients during and outside a migraine attack.

RESULTS

One hundred forty-nine patients (98 M and 51 TTHA). Total Mig-SCog score was higher in migraine patients than TTH (8.0 ± 4.1 vs 3.4 ± 3.2, P < .0001). Sixty-three patients took part in the next part of the study. Migraine patients rated the Mig-SCog higher for migraine (7.9 ± 4.6) than for non-headache pain (2.3 ± 2.9, P < .0006) or pain-free (1.6 ± 2.4, P < .0006). In the final phase of the study, 38 patients Mig-SCog scores were not significantly different whether obtained during or outside an M attack (P = .26).

CONCLUSIONS

Attack-related subjective cognitive symptoms, assessed by Mig-SCog scores, differed between migraine and TTH patients. The Mig-SCog scores from migraine patients were found to be higher during migraine than during non-headache pain or pain-free conditions. Patient scoring from memory for usual attacks was not significantly different to scoring within attacks, We believe this demonstrates negligible recall bias.

Pharmacokinetic-Pharmacodynamic Modeling of Intravenous and Oral Topiramate and Its Effect on the Symbol-Digit Modalities Test in Adult Healthy Volunteers

A sequential pharmacokinetic-pharmacodynamic (PK-PD) modeling approach was used to quantify the effects of a single dose of topiramate (100 or 200 mg) on working memory, attention, and psychomotor speed as measured by the Symbol-Digit Modalities Test (SDMT). Established on data pooled from 3 randomized, crossover studies in healthy subjects (19-55 years of age), using both oral and a novel stable-labeled intravenous (IV) formulation of topiramate, an inhibitory Emax model was found to characterize the topiramate concentration-SDMT score relationship well. At the EC50 of 2.85 μg/mL, this topiramate plasma concentration value was estimated to be associated with a 25.5% reduction of SDMT score relative to baseline. Age was an important determinant of the baseline SDMT score, with an estimated decrease of 1.13% in baseline SDMT score with every year of age. Moreover, this approach enabled the quantification of the practice effect observed with repeated administration of the neuropsychological test over shorter testing intervals than have previously been reported in the literature. The finding of a significant effect following a single dose of topiramate in the range widely used to treat migraine and epilepsy needs to be evaluated in a broader patient population undergoing chronic treatment, as the narrow range of resultant concentrations limits the generalizability of the findings.

Comparison of Cognitive Impairment between Patients having Epilepsy and Psychogenic Nonepileptic Seizures

INTRODUCTION

The aim of this study was to evaluate cognitive impairment in patients having epilepsy or psychogenic nonepileptic seizures (PNESs) using selected neuropsychological tests at different time periods related to the seizure.

METHODS

In this study, selected neurocognitive tests were administered to the patients. Within 24 h, the previously applied neurocognitive tests were repeated within 24 h following the observation of typical seizures when monitoring and normalizing electroencephalography (EEG) activity. Basal neurocognitive tests were also administered to the healthy control group, and repeat neurocognitive evaluation was performed within 24-96 h.

RESULTS

The basal neurocognitive evaluation revealed that verbal learning and memory scores as well as Stroop test interference time were significantly lower in the PNES group compared with those in the controls. In the basal cognitive tests administered to the patients with epilepsy, verbal learning and memory scores, long-term memory, and total recognition test scores were significantly lower than those of the controls. Following the repeat cognitive tests, significant progress was found in the verbal categorical fluency score of the PNES group. No significant difference was determined in the epilepsy group. Significant contraction was determined in the Stroop interference time in the control group, but no similar change was recorded in the epilepsy or PNES groups.

CONCLUSION

While memory problems seemed to be most prominent in the assessed patients with epilepsy, attention and executive function problems were more dominant in the patients with PNESs. These findings are probably related to numerous factors such duration of disease, mood disorders, and specific drug use. No deterioration in attention and executive functions was reported in the early post-seizure period in either patient group.

The effects of antiepileptic drugs on cognitive functional magnetic resonance imaging

The cognitive dysfunction caused by antiepileptic drugs (AEDs) has been extensively described, although the mechanisms underlying such collateral effects are still poorly understood. The combination of functional magnetic resonance imaging (fMRI) studies with pharmacological intervention (pharmaco-MRI or ph-MRI) offers the opportunity to investigate the effect of drugs such as AEDs on brain activity, including cognitive tasks. Here we review the studies that investigated the effects of AEDs [topiramate (TPM), lamotrigine (LMT), carbamazepine (CBZ), pregabalin (PGB), valproate (VPA) and levetiracetam (LEV)] on cognitive fMRI tasks. Despite the scarcity of fMRI studies focusing on the impact of AEDs on cognitive task, the results of recent work have provided important information about specific drug-related changes of brain function.

Peripheral nerve injury and gabapentin, but not their combination, impair attentional behavior via direct effects on noradrenergic signaling in the brain

Chronic pain after peripheral nerve damage is often accompanied by a reduction in prefrontal cortex (PFC)-related cognitive functions, which are regulated by noradrenaline, released from efferents originating in the locus coeruleus (LC). L5 to L6 spinal nerve ligation (SNL) in rats increased tissue content and extracellular concentrations of noradrenaline in microdialysates from the PFC, and impaired attentional level in the novel object recognition test. Systemic gabapentin, commonly used to treat chronic pain, impaired the novel object recognition task in normal but not SNL animals. Accordingly, gabapentin increased c-fos expression in LC neurons and noradrenaline release in the PFC in normal animals, but in SNL animals, gabapentin failed to increase c-fos expression in LC neurons projecting to the PFC and failed to increase noradrenaline release in the PFC. In contrast, locally perfused gabapentin reduced noradrenaline release in the PFC in vivo and in PFC synaptosomes in vitro. SNL- and gabapentin-induced impairment of novel object recognition task were reversed by intraperitoneal injection of the α1-adrenoceptor antagonist prazosin. These results suggest that increase in noradrenergic tone, induced by nerve injury or gabapentin, impairs PFC functions possibly via α1-adrenoceptor-mediated mechanisms; that the net effect of gabapentin on noradrenaline release in the PFC would depend on sometimes opposing actions at different sites; and that nerve injury selectively impairs the response to gabapentin in PFC-projecting neurons in the LC.

Key issues in addressing the comorbidity of attention deficit hyperactivity disorder and pediatric epilepsy

Attention deficit hyperactivity disorder (ADHD) is a common comorbidity of epilepsy encountered by clinicians. However, relatively little information is available to guide optimal diagnostic and treatment strategies. Differentiating ADHD from effects of epilepsy requires careful history taking and emphasis upon characteristic symptoms and course of illness. Rating scales for ADHD are well validated and may aid clinical management. Use of antiepileptic drugs may cause cognitive or behavioral side effects yet may improve behavior in some cases. Historically, clinicians have been hesitant to treat ADHD comorbidity for fear of lowering the seizure threshold. However, an aggregate of recent evidence now suggests that stimulants may be well tolerated and effective for ADHD comorbid with epilepsy. Studies that further clarify pathophysiology and treatment outcomes are needed in order to enhance clinical efficacy and quality of life for this population.

Topiramate and cognitive impairment: evidence and clinical implications

Topiramate is an antiepileptic drug (AED) with multiple mechanisms of action that has been shown to be effective in a number of neuropsychiatric disorders. However, cognitive dysfunction is frequently observed in such patients, often representing a relevant challenge in their management. Moreover, there is a long-held recognition that AEDs may profoundly affect cognitive functions. This paper reviews available data on cognitive adverse events in patients with neurological disorders treated with topiramate, discussing the role of different contributing factors such as the pharmacological properties of the drug, the specific features of the brain disorder, and other variables pertinent to the discussion. All studies agree that up to 10% of patients may complain of treatment-emergent adverse events on cognition. Such problems occur early during treatment (i.e. within 6 weeks) and emerge in a dose-dependent fashion, suggesting that such prevalence may be significantly reduced using the drug in monotherapy and adopting individualized doses and titration schedules. The magnitude of the problem is generally mild to moderate and the subjective perception of the patient needs to be taken into account. In fact, apart from language problems, data are not conclusive. Comparisons with new AEDs are limited to levetiracetam and lamotrigine, in both cases generally disfavoring topiramate, while data regarding first-generation AEDs show clear differences only for verbal fluency.

Predictive validity of a MK-801-induced cognitive impairment model in mice: implications on the potential limitations and challenges of modeling cognitive impairment associated with schizophrenia preclinically

Cognitive impairment associated with schizophrenia (CIAS) is a major and disabling symptom domain of the disease that is generally unresponsive to current pharmacotherapies. Critically important to the discovery of novel therapeutics for CIAS is the utilization of preclinical models with robust predictive validity. We investigated the predictive validity of MK-801-induced memory impairments in mouse inhibitory avoidance (MK-IA) as a preclinical model for CIAS by investigating compounds that have been tested in humans, including antipsychotics, sodium channel blocker mood stabilizers, and putative cognitive enhancers. The atypical antipsychotic clozapine, as well as risperidone and olanzapine (see Brown et al., 2013), had no effect on MK-801-induced memory impairments. For sodium channel blockers, carbamazepine significantly attenuated memory impairments induced by MK-801, whereas lamotrigine had no effect. Nicotine, donepezil, modafinil, and xanomeline all significantly attenuated MK-801-induced memory impairments, but the magnitude of effects and the dose-responses observed varied across compounds. Clinically, only acute administration of nicotine has demonstrated consistent positive effects on CIAS, while inconsistent results have been reported for lamotrigine, donepezil, and modafinil; atypical antipsychotics produce only moderate improvements at best. A positive clinical signal has been observed with xanomeline, but only in a small pilot trial. The results presented here suggest that the MK-IA model lacks robust predictive validity for CIAS as the model is likely permissive and may indicate false positive signals for compounds and mechanisms that lack clear clinical efficacy for CIAS. Our findings also highlight the potential limitations and challenges of using NMDA receptor antagonists in rodents to model CIAS.

Neuropsychology of migraine: present status and future directions

Migraine is recognized as a primarily neural condition. Changes in neural physiology have been consistently identified in migraineurs. Numerous studies are available that evaluate physical and functional differences between migraineurs and headache-free controls. The most prominent neuroimaging findings reported in migraine sufferers have been white matter changes. However, physical changes on neuroimaging have not been clearly correlated with functional impairment in migraineurs. The current literature addressing the neuropsychologic consequences of migraine has been far from conclusive, and reports of cognitive testing in adult migraineurs and controls has yielded inconsistent results. Neuropsychologic testing suggests that there may be some subtle but possibly significant changes in cognition that occur both during and between migraine episodes. A finding emerging with some consistency is that migraine patients with aura experience more neuropsychologic deficits than migraine patients without aura. The few studies that assess nonmigraine headache suggest that physical changes may not be unique to migraine, although neuropsychologic changes do appear to be limited to migraineurs. An examination of the unmet needs and priorities for future research addressing this important topic is provided.

Use of the ketogenic diet as a treatment for epilepsy refractory to drug treatment

The ketogenic diet is a high-fat, low-carbohydrate and low-protein diet used in the treatment of epilepsy that does not respond to antiepileptic drugs. The diet has been found to be very effective in treating intractable epilepsy in children. There is also some evidence that the diet is useful in treating drug-resistant epilepsy in infants, adolescents and adults. This paper traces the history and development of the ketogenic diet and reviews the clinical and animal research investigating its effects.

Topiramate for the treatment of epilepsy and other nervous system disorders

Initially synthesized as an oral hypoglycemic agent, topiramate was approved for use as an anticonvulsant in 1996. Its broad spectrum efficacy in epilepsy, including as monotherapy and in children, is well established. Topiramate has also been used in the management of nonepileptic neurologic and psychiatric conditions, including migraine prophylaxis (with firmly established efficacy), obesity (with some evidence of long-term maintenance of weight loss), substance dependence, bipolar disorder and neuropathic pain, and it has been investigated as a possible neuroprotective agent. Paresthesias and cognitive side effects are the most common troublesome adverse effects. Recent trends towards lower doses may help achieve the best combination of efficacy and tolerability.

Post-traumatic epilepsy: current and emerging treatment options

Traumatic brain injury (TBI) leads to many undesired problems and complications, including immediate and long-term seizures/epilepsy, changes in mood, behavioral, and personality problems, cognitive and motor deficits, movement disorders, and sleep problems. Clinicians involved in the treatment of patients with acute TBI need to be aware of a number of issues, including the incidence and prevalence of early seizures and post-traumatic epilepsy (PTE), comorbidities associated with seizures and anticonvulsant therapies, and factors that can contribute to their emergence. While strong scientific evidence for early seizure prevention in TBI is available for phenytoin (PHT), other antiepileptic medications, eg, levetiracetam (LEV), are also being utilized in clinical settings. The use of PHT has its drawbacks, including cognitive side effects and effects on function recovery. Rates of recovery after TBI are expected to plateau after a certain period of time. Nevertheless, some patients continue to improve while others deteriorate without any clear contributing factors. Thus, one must ask, 'Are there any actions that can be taken to decrease the chance of post-traumatic seizures and epilepsy while minimizing potential short- and long-term effects of anticonvulsants?' While the answer is 'probably,' more evidence is needed to replace PHT with LEV on a permanent basis. Some have proposed studies to address this issue, while others look toward different options, including other anticonvulsants (eg, perampanel or other AMPA antagonists), or less established treatments (eg, ketamine). In this review, we focus on a comparison of the use of PHT versus LEV in the acute TBI setting and summarize the clinical aspects of seizure prevention in humans with appropriate, but general, references to the animal literature.

Topiramate: Effects on cognition in patients with epilepsy, migraine headache and obesity

This paper reviews the clinical implications of topiramate (TPM)-induced cognitive deficits in patients with epilepsy, migraine headache, obesity, and in normal populations, followed by reviews of the literature describing the reversal of such deficits upon medication discontinuation. It also discusses animal investigations of TPM's role of neuroprotection in brain injury. TPM's most intolerable adverse effects (AEs) are on verbal fluency and reaction time, resulting in high discontinuation rates in patients taking it for epilepsy and migraine headache. However, because TPM is so effective in the treatment of epilepsy and migraine headache, its use is expected to continue. There appears to be greater tolerance of TPM's cognitive AEs when it is used in the treatment of obesity, perhaps because of the lower doses required. Research attempting to predict the populations most vulnerable to the cognitive effects caused by TPM is ongoing. Studies suggest that one such population may include patients with a past psychiatric history. Slow titration and administration of the lowest possible doses may decrease risk of cognitive deficits.

Associations between cognitive performance and cortisol reaction to the DEX/CRH test in patients recovered from depression

BACKGROUND

Hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis in major depression (MDD) is one of the most reliably reported neurobiological characteristics of affective disorders. Whether these alterations in HPA axis regulation are limited to the acute stage of MDD or whether they persist after recovery, remains ambiguous. A relationship between hypercortisolemia and cognitive dysfunction in acutely depressed patients has been repeatedly observed and it was also demonstrated in a number of studies that a discrete cognitive impairment often persists in the remitted state of depression. In the present study we were interested, whether these subtle impairments in cognitive functioning observed in patients recovered from depression compared to healthy control subjects are associated with HPA axis feedback sensitivity.

METHODS

In 20 recovered patients and 20 matched healthy controls we assessed HPA axis feedback sensitivity with the combined dexamethasone suppression/corticotropin-releasing-hormone (DEX/CRH) challenge test. Furthermore cognitive performance was investigated with respect to the following domains: verbal memory (Auditory Verbal Learning Test, VLMT), attention and executive control (Trail Making Test, TMT-A/B) as well as verbal fluency (Controlled Oral Word Association Test, COWAT).

RESULTS

Recovered patients showed a significantly poorer cognitive performance compared to healthy controls (all p<.05). With regard to HPA-axis activity, no overall difference was observed in the DEX/CRH test between recovered patients and controls. In recovered patients however, a significant association was observed between cortisol response and verbal memory (main effect VLMT trial 1-5: p=.046), attention (main effect TMT-A: p=.015) and executive functioning in terms of set shifting (interaction samples*TMT-B: p=.018). Poorer test performance was related to increased cortisol levels in response to challenge.

CONCLUSIONS

The present findings suggest that patients recovered from MDD are especially vulnerable toward detrimental effects of subtle HPA axis disturbances on cognitive performance.

Cognitive side-effects of antiepileptic drugs in children

Although the causes of cognitive impairment in patients with epilepsy have not been completely elucidated, three factors are clearly involved: the underlying etiology of epilepsy, the effects of seizures or the epileptiform EEG discharges themselves, and the central nervous system effects of antiepileptic drugs (AEDs). All commonly used AEDs have some effect on cognitive function, and the effect may be substantial when crucial functions are involved, such as learning in children. With phenobarbital, there is a high risk for serious cognitive effects impacting attention and memory. Phenytoin may affect mental speed, mainly in higher dosing and polytherapy. Moderate monotherapy doses do not seem to induce much effect. Valproate does not seem to impair cognition if sufficiently controlled for hyperammonemia. For carbamazepine, there are conflicting reports, which may be due to selection bias or dosing. For oxcarbazepine, there is no evidence for any detrimental change compared to valproate but mild improvements on attentional tests. For topiramate, there is clear evidence for topiramate-induced cognitive impairment (attention, memory, and language function) in adults and children. Although data is sketchy, levetiracetam does not seem to have a negative impact on cognition. For lamotrigine, there is evidence of a cognitive-enhancing effect on attention. No evidence for cognitive side-effects has been found for vigabatrin. Ethosuximide is not associated with cognitive impairment although the evidence is sketchy. For gabapentin, tiagabine, zonisamide, and rufinamide no studies in children are available.

Pharmacological approaches in bipolar disorders and the impact on cognition: a critical overview

OBJECTIVE

Historically, pharmacological treatments for bipolar disorders (BD) have been associated with neurocognitive side-effects. We reviewed studies which assessed the impact of several psychopharmacological drugs on the neurocognitive function of BD patients.

METHOD

The PubMed database was searched for studies published between January 1980 and February 2011, using the following terms: bipolar, bipolar disorder, mania, manic episode, or bipolar depression, cross-referenced with cognitive, neurocognitive, or neuropsychological, cross-referenced with treatment.

RESULTS

Despite methodological flaws in the older studies and insufficient research concerning the newer agents, some consistent findings emerged from the review; lithium appears to have definite, yet subtle, negative effects on psychomotor speed and verbal memory. Among the newer anticonvulsants, lamotrigine appears to have a better cognitive profile than carbamazepine, valproate, topiramate, and zonisamide. More long-term studies are needed to better understand the impact of atypical antipsychotics on BD patients' neurocognitive functioning, both in monotherapy and in association with other drugs. Other agents, like antidepressants and cognitive enhancers, have not been adequately studied in BD so far.

CONCLUSION

Pharmacotherapies for BD should be chosen to minimize neurocognitive side-effects, which may already be compromised by the disease process itself. Neurocognitive evaluation should be considered in BD patients to better evaluate treatment impact on neurocognition. A comprehensive neuropsychological evaluation also addressing potential variables and key aspects such as more severe cognitive deficits, comorbidities, differential diagnosis, and evaluation of multiple cognitive domains in longitudinal follow-up studies are warranted.