The ketogenic diet for intractable epilepsy in adults: preliminary results

Ketogenic diet alters dopaminergic activity in the mouse cortex

The present study was conducted to determine if the ketogenic diet altered basal levels of monoamine neurotransmitters in mice. The catecholamines dopamine (DA) and norephinephrine (NE) and the indolamine serotonin (5HT) were quantified postmortem in six different brain regions of adult mice fed a ketogenic diet for 3 weeks. The dopamine metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) and the serotonin metabolite 5-hydroxyindole acetic acid (5HIAA) were also measured. Tissue punches were collected bilaterally from the motor cortex, somatosensory cortex, nucleus accumbens, anterior caudate-putamen, posterior caudate-putamen and the midbrain. Dopaminergic activity, as measured by the dopamine metabolites to dopamine content ratio - ([DOPAC]+[HVA])/[DA] - was significantly increased in the motor and somatosensory cortex regions of mice fed the ketogenic diet when compared to those same areas in brains of mice fed a normal diet. These results indicate that the ketogenic diet alters the activity of the meso-cortical dopaminergic system, which may contribute to the diet's therapeutic effect in reducing epileptic seizure activity.

Selection of antiepileptic drugs in older people

OPINION STATEMENT

Elderly people are one of the fastest-growing populations in the United States, and the incidence of epilepsy in older people is much higher than in other population subgroups. This age group is the most vulnerable because of the increased incidence of multiple medical comorbidities, including stroke. The diagnosis of epilepsy is extremely challenging and often delayed in this age group because of an atypical presentation. Seizures are manifest through extremely vague complaints, such as episodes of altered mental status or memory lapses. Once the diagnosis is established by careful history taking and diagnostic testing, anticonvulsants are the mainstay of treatment. The choice of anticonvulsants in elderly patients requires careful evaluation of medical comorbidities, which vary on an individual basis. This subgroup also is more susceptible to adverse effects because of the physiologic changes in the body due to older age, which affect the pharmacokinetics of most anticonvulsants. The ideal drug in this age group should have linear pharmacokinetics, fewer adverse effects, minimal or no drug-drug interactions, no enzyme induction/inhibition, a long half-life, and minimal protein binding, and should be cost-effective. As such, there is no ideal drug for this patient population, although both older- and newer-generation anticonvulsants are used for long-term treatment. Most newer anticonvulsants have the advantage of a favorable pharmacokinetic profile, minimal or no drug-drug interactions, and fewer adverse events, as well as being well tolerated. The older anticonvulsants still are widely used, because the newer anticonvulsants are much more expensive.

Can an early 24-hour EEG predict the response to the ketogenic diet? A prospective study in 34 children and adults with refractory epilepsy treated with the ketogenic diet

PURPOSE

We examined whether early EEG changes in a 24-h EEG at 6 weeks of treatment were related to the later clinical response to the ketogenic diet (KD) in a 6-month period of treatment.

METHODS

We examined 34 patients with heterogeneous epilepsy syndromes (21 children, 13 adults) and found 9 clinical responders (≥50% seizure reduction); this is a responder rate of 26%. We visually counted the interictal epileptic discharge index (IED index) in % during 2h of wakefulness and in the first hour of sleep (method 1), and also globally reviewed EEG changes (method 2), while blinded to the effect of the KD.

RESULTS

At group level we saw a correlation between nocturnal reduction of IED-index at 6 weeks and seizure reduction in the follow-up period. A proportional reduction in IED index of 30% from baseline in the sleep EEG, was associated with being a responder to the diet (Pearson Chi-square p=0.04). EEG scoring method 2 observed a significantly larger proportion of patients with EEG-improvement in sleep in KD responders than in non-responders (p=0.03). At individual level, however, EEG changes did not correlate very strongly to the response to the diet, as IED reduction in sleep was also seen in 15% (method 1) to 26% (method 2) of the non-responders.

CONCLUSION

Nocturnal reduction of IEDs is related to the response to the KD, however in daily clinical practice, an early EEG to predict seizure reduction should not be advised for individual patients.

Ketogenic diet in adolescents and adults with epilepsy

PURPOSE

The ketogenic diet is an alternative treatment for patients with refractory epilepsy. Most studies to date report dietary response in children. There are limited data evaluating the efficacy of the ketogenic diet in adults. This is a report of the long-term outcome in a largely adult population of patients treated with the ketogenic diet for epilepsy.

METHOD

Twenty-nine adult and adolescent patients (mean age 32 years, range 11-51) were initiated on the ketogenic diet and followed until diet discontinuation. Clinical response and adverse effects were noted during the duration of the diet.

RESULTS

Fifty-two percent of patients had a significant reduction in seizure frequency on the ketogenic diet, including 45% with ≥50% reduction in seizure frequency. Thirty-one percent had no improvement, seven percent were unable to successfully initiate the diet, and 10% had a >50% increase in seizure frequency. The diet was continued for a mean of 9 months (range 0.13-35 months), with five patients completing ≥23 months. There was a trend toward better response and better tolerability/longer duration in patients with symptomatic generalized epilepsy. The diet was generally well-tolerated, but undesired weight loss and constipation were the most frequent adverse effects.

CONCLUSION

The ketogenic diet can be used safely in the adult and adolescent population, with a response rate similar to those seen in children. Patient with symptomatic generalized epilepsy may be particularly good candidates for this type of dietary treatment.

Long-term ketogenic diet causes glucose intolerance and reduced β- and α-cell mass but no weight loss in mice

High-fat, low-carbohydrate ketogenic diets (KD) are used for weight loss and for treatment of refractory epilepsy. Recently, short-time studies in rodents have shown that, besides their beneficial effect on body weight, KD lead to glucose intolerance and insulin resistance. However, the long-term effects on pancreatic endocrine cells are unknown. In this study we investigate the effects of long-term KD on glucose tolerance and β- and α-cell mass in mice. Despite an initial weight loss, KD did not result in weight loss after 22 wk. Plasma markers associated with dyslipidemia and inflammation (cholesterol, triglycerides, leptin, monocyte chemotactic protein-1, IL-1β, and IL-6) were increased, and KD-fed mice showed signs of hepatic steatosis after 22 wk of diet. Long-term KD resulted in glucose intolerance that was associated with insufficient insulin secretion from β-cells. After 22 wk, insulin-stimulated glucose uptake was reduced. A reduction in β-cell mass was observed in KD-fed mice together with an increased number of smaller islets. Also α-cell mass was markedly decreased, resulting in a lower α- to β-cell ratio. Our data show that long-term KD causes dyslipidemia, a proinflammatory state, signs of hepatic steatosis, glucose intolerance, and a reduction in β- and α-cell mass, but no weight loss. This indicates that long-term high-fat, low-carbohydrate KD lead to features that are also associated with the metabolic syndrome and an increased risk for type 2 diabetes in humans.

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.

Monocarboxylate transporters in temporal lobe epilepsy: roles of lactate and ketogenic diet

Epilepsy is a serious neurological disorder that affects approximately 1 % of the general population, making it one of the most common disorders of the central nervous system. Furthermore, up to 40 % of all patients with epilepsy cannot control their seizures with current medications. More efficacious treatments for medication refractory epilepsy are therefore needed. A better understanding of the mechanisms that cause this disorder is likely to facilitate the discovery of such treatments. Impairment in cerebral energy metabolism has been proposed as a possible causative factor in the pathogenesis of temporal lobe epilepsy (TLE), which is one of the most common types of medication-refractory epilepsies in adults. In this review, we will discuss some of the current hypotheses regarding the possible causal relationship between brain energy metabolism and TLE. Emphasis will be placed on the role of energy substrates (lactate and ketone bodies) and their transporter molecules, particularly monocarboxylate transporters 1 and 2 (MCT1 and MCT2). We recently reported that the cellular distribution of MCT1 and MCT2 is perturbed in the hippocampus in patients with TLE. The changes may be an adaptive response aimed at keeping high levels of lactate in the epileptic tissue, which may serve to counteract epileptic activity by downregulating cAMP levels through the lactate receptor GPR81, newly discovered in hippocampus. We propose that the perturbation of MCTs may be further involved in the pathophysiology of TLE by influencing brain energy homeostasis, mitochondrial function, GABA-ergic and glutamatergic neurotransmission, and flux of lactate through the brain.

Restricted calorie ketogenic diet for the treatment of glioblastoma multiforme

Glioblastoma multiforme is the most common malignant primary brain tumor in adults and generally considered to be universally fatal. Glioblastoma multiforme accounts for 12% to 15% of all intracranial neoplasms and affects 2 to 3 adults per every 100,000 in the United States annually. In children glioblastoma multiforme accounts for only approximately 7% to 9% of central nervous system tumors. The mean survival rate in adults after diagnosis ranges from 12 to 18 months with standard therapy and 3 to 6 months without therapy. The prognosis in children is better compared to adult tumor onset with a mean survival of approximately 4 years following gross total surgical resection and chemotherapy. There have been few advances in the treatment of glioblastoma multiforme in the past 40 years beyond surgery, radiotherapy, chemotherapy, and corticosteroids. For this reason a restrictive calorie ketogenic diet, similar to that used in children to control drug resistant seizure activity, has been advanced as an alternative adjunctive treatment to help prolonged survival. This article reviews the science of tumor metabolism and discusses the mechanism of calorie restriction, cellular energy metabolism, and how dietary induced ketosis can inhibit cancer cell's energy supply to slow tumor growth.

Ketogenic diet improves core symptoms of autism in BTBR mice

Autism spectrum disorders share three core symptoms: impaired sociability, repetitive behaviors and communication deficits. Incidence is rising, and current treatments are inadequate. Seizures are a common comorbidity, and since the 1920's a high-fat, low-carbohydrate ketogenic diet has been used to treat epilepsy. Evidence suggests the ketogenic diet and analogous metabolic approaches may benefit diverse neurological disorders. Here we show that a ketogenic diet improves autistic behaviors in the BTBR mouse. Juvenile BTBR mice were fed standard or ketogenic diet for three weeks and tested for sociability, self-directed repetitive behavior, and communication. In separate experiments, spontaneous intrahippocampal EEGs and tests of seizure susceptibility (6 Hz corneal stimulation, flurothyl, SKF83822, pentylenetetrazole) were compared between BTBR and control (C57Bl/6) mice. Ketogenic diet-fed BTBR mice showed increased sociability in a three-chamber test, decreased self-directed repetitive behavior, and improved social communication of a food preference. Although seizures are a common comorbidity with autism, BTBR mice fed a standard diet exhibit neither spontaneous seizures nor abnormal EEG, and have increased seizure susceptibility in just one of four tests. Thus, behavioral improvements are dissociable from any antiseizure effect. Our results suggest that a ketogenic diet improves multiple autistic behaviors in the BTBR mouse model. Therefore, ketogenic diets or analogous metabolic strategies may offer novel opportunities to improve core behavioral symptoms of autism spectrum disorders.

Ketogenic diets and thermal pain: dissociation of hypoalgesia, elevated ketones, and lowered glucose in rats

Ketogenic diets (KDs) are high-fat, low-carbohydrate formulations effective in treating medically refractory epilepsy, and recently we demonstrated lowered sensitivity to thermal pain in rats fed a KD for 3 to 4 weeks. Regarding anticonvulsant and hypoalgesic mechanisms, theories are divided as to direct effects of increased ketones and/or decreased glucose, metabolic hallmarks of these diets. To address this point, we characterized the time course of KD-induced thermal hypoalgesia, ketosis, and lowered glucose in young male rats fed ad libitum on normal chow or KDs. A strict 6.6:1 (fat:[carbohydrates + protein], by weight) KD increased blood ketones and reduced blood glucose by 2 days of feeding, but thermal hypoalgesia did not appear until 10 days. Thus, ketosis and decreased glucose are not sufficient for hypoalgesia. After feeding a 6.6:1 KD for 19 days, decreased thermal pain sensitivity and changes in blood chemistry reversed 1 day after return to normal chow. Effects were consistent between 2 different diet formulations: a more moderate and clinically relevant KD formula (3.0:1) produced hypoalgesia and similar changes in blood chemistry as the 6.6:1 diet, thus increasing translational potential. Furthermore, feeding the 3.0:1 diet throughout an extended protocol (10-11 weeks) revealed that significant hypoalgesia and increased ketones persisted whereas low glucose did not, demonstrating that KD-induced hypoalgesia does not depend on reduced glucose. In separate experiments we determined that effects on thermal pain responses were not secondary to motor or cognitive changes. Together, these findings dissociate diet-related changes in nociception from direct actions of elevated ketones or decreased glucose, and suggest mechanisms with a slower onset in this paradigm. Overall, our data indicate that metabolic approaches can relieve pain.

PERSPECTIVE

Chronic pain is a common and debilitating condition. We show that a KD, a high-fat, very low carbohydrate diet well known for treating epilepsy, lowers sensitivity to thermal pain in rats. This reduced pain is not temporally correlated with hallmark diet-induced changes in blood glucose and ketones.

Seizure treatment in transplant patients

OPINION STATEMENT

Solid organ transplantation is frequently complicated by a spectrum of seizure types, including single partial-onset or generalized tonic-clonic seizures, acute repetitive seizures or status epilepticus, and sometimes the evolution of symptomatic epilepsy. There is currently no specific evidence involving the transplant patient population to guide the selection, administration, or duration of antiepileptic drug (AED) therapy, so familiarity with clinical AED pharmacology and application of sound judgment are necessary for successful patient outcomes. An initial detailed search for symptomatic seizure etiologies, including metabolic, infectious, cerebrovascular, and calcineurin inhibitor treatment-related neurotoxic complications such as posterior reversible encephalopathy syndrome (PRES), is imperative, as underlying central nervous system disorders may impose additional serious risks to cerebral or general health if not promptly detected and appropriately treated. The mainstay for post-transplant seizure management is AED therapy directed toward the suspected seizure type. Unfavorable drug interactions could place the transplanted organ at risk, so choosing an AED with limited interaction potential is also crucial. When the transplanted organ is dysfunctional or vulnerable to rejection, AEDs without substantial hepatic metabolism are favored in post-liver transplant patients, whereas after renal transplantation, AEDs with predominantly renal elimination may require dosage adjustment to prevent adverse effects. Levetiracetam, gabapentin, pregabalin, and lacosamide are drugs of choice for treatment of partial-onset seizures in post-transplant patients given their efficacy spectrum, generally excellent tolerability, and lack of drug interaction potential. Levetiracetam is the drug of choice for primary generalized seizures in post-transplant patients. When intravenous drugs are necessary for acute seizure management, benzodiazepines and fosphenytoin are the traditional and best evidence-based options, although intravenous levetiracetam, valproate, and lacosamide are emerging options. Availability of several newer AEDs has greatly expanded the therapeutic armamentarium for safe and efficacious treatment of post-transplant seizures, but future prospective clinical trials and pharmacokinetic studies within this specific patient population are needed.

The nervous system and metabolic dysregulation: emerging evidence converges on ketogenic diet therapy

A link between metabolism and brain function is clear. Since ancient times, epileptic seizures were noted as treatable with fasting, and historical observations of the therapeutic benefits of fasting on epilepsy were confirmed nearly 100 years ago. Shortly thereafter a high fat, low-carbohydrate ketogenic diet (KD) debuted as a therapy to reduce seizures. This strict regimen could mimic the metabolic effects of fasting while allowing adequate caloric intake for ongoing energy demands. Today, KD therapy, which forces predominantly ketone-based rather than glucose-based metabolism, is now well-established as highly successful in reducing seizures. Cellular metabolic dysfunction in the nervous system has been recognized as existing side-by-side with nervous system disorders - although often with much less obvious cause-and-effect as the relationship between fasting and seizures. Rekindled interest in metabolic and dietary therapies for brain disorders complements new insight into their mechanisms and broader implications. Here we describe the emerging relationship between a KD and adenosine as a way to reset brain metabolism and neuronal activity and disrupt a cycle of dysfunction. We also provide an overview of the effects of a KD on cognition and recent data on the effects of a KD on pain, and explore the relative time course quantified among hallmark metabolic changes, altered neuron function and altered animal behavior assessed after diet administration. We predict continued applications of metabolic therapies in treating dysfunction including and beyond the nervous system.

The ketogenic diet as a treatment option in adults with chronic refractory epilepsy: efficacy and tolerability in clinical practice

The ketogenic diet (KD) is a high-fat, low-protein, low-carbohydrate diet that is used as a treatment for patients with difficult-to-control epilepsy. The present study assesses the efficacy and tolerability of the KD as an add-on therapy in adults with chronic refractory epilepsy. 15 adults were treated with the classical diet or MCT diet. During a follow-up period of 1 year we assessed seizure frequency, seizure severity, tolerability, cognitive performance, mood and quality of life (QOL). We found a significant reduction in seizures among the patients who followed the diet at least 1 year (n=5). Of these 5 patients, 2 had a reduction between 50 and 90%. Analyzing the study months separately, we found a seizure reduction of ≥50% in 26.6% of the patients during at least 1 month of treatment. Common side-effects were gastrointestinal disorders, loss of weight and fatigue. There was a considerable, non-significant improvement found in mood and QOL scores. Improvements were independent of reduction in seizure frequency, indicating that the effects of the KD reach further than seizure control.

E-mail management of the modified Atkins Diet for adults with epilepsy is feasible and effective

PURPOSE

The modified Atkins Diet (MAD) is an effective dietary treatment for children with epilepsy. However, adults may have limited access to this therapy because of lack of availability of dietitian or nutrition support or familiarity with the diet by their treating neurologist. This study was designed to investigate the tolerability and efficacy of the MAD administered solely via e-mail to adults with pharmacoresistant epilepsy.

METHODS

A prospective, open-label, proof-of-principle 3-month study design was employed. Adults were enrolled, instructed on how to self-administer a 20 g carbohydrate per day MAD, and followed by the investigators only via e-mail. There were no clinic visits or dietitian contacts during the study period.

KEY FINDINGS

Twenty-five participants (median age 30 years [range 18-66 years], 68% female) consented and 22 started the MAD. The median prior anticonvulsants was 5 (range 2-10) and seizure frequency was 5 per week (range 1-140). Urinary ketosis was achieved in 21 participants (95%), of which 16 (76%) reported at least 40 mg/dl (moderate). Twenty-one participants (95%) remained on the MAD at 1 month and 14 (64%) at 3 months. After 1 month, 9 (41%) had >50% seizure reduction including one (5%) with >90% seizure reduction using intent-to-treat analysis. After 3 months, 6 (27%) had >50% seizure reduction including 3 (14%) with >90% seizure reduction. The mean ketogenic ratio was 1.1:1 (fat:carbohydrates and protein) for those who provided a MAD food record at follow-up. Over the study period, the median number of e-mails sent by the participants was 6 (range 1-19). The most frequent side effect was weight loss.

SIGNIFICANCE

E-mail administration of the MAD to adults with refractory epilepsy appears to be feasible and effective. Therefore, when dietitian or physician support is limited for adult patients with epilepsy, remote access via telemedicine could provide an alternative.

Dietary treatment of epilepsy: rebirth of an ancient treatment

Since its introduction in 1921, the ketogenic diet has been in continuous use for children with difficult-to-control epilepsy. After decades of relative disuse, it is now both extremely popular and well studied, with approximately two-thirds of children demonstrating significant seizure reduction after 6 months. It is being used for less intractable seizures in children as well as recently adults. Modifications that help improve tolerability include the medium chain triglyceride diet, modified Atkins diet, and low glycemic index treatment. Major side effects include acidosis, increased cholesterol, kidney stones, gastroesophageal reflux, and growth disturbance. However, these side effects are usually treatable and nowadays often even preventable. Future non-epilepsy indications such as Alzheimer disease, amyotrophic lateral sclerosis, autism, and brain tumors are under active investigation. This dietary treatment for epilepsy has undergone a rebirth. Its widespread use in Poland and Europe is a welcome additional treatment for those with drug-resistant epilepsy.

The ketogenic diet for medically and surgically refractory status epilepticus in the neurocritical care unit

BACKGROUND

Refractory status epilepticus carries a high risk of morbidity and mortality despite, and at times as a result of, aggressive pharmacologic interventions. Dietary therapies have been used for almost a century in children for controlling medically refractory seizures and status epilepticus and recent studies suggest efficacy and safety in adults as well.

METHODS

Case report and literature review.

RESULTS

We describe a case of medically and surgically refractory status epilepticus that was controlled after initiation of the ketogenic diet and maintenance with the modified Atkins diet in an adult in the neurocritical care unit.

CONCLUSIONS

Dietary therapy should be considered as a treatment option in adult patients with refractory status epilepticus.

Dietary therapies for epilepsy: future research

Since 1921, dietary therapies have remained valuable options in the treatment of intractable childhood epilepsy. The traditional ketogenic diet has been well demonstrated, including in a recent randomized, controlled trial, as being highly effective. More recent alternative diets such as the medium-chain triglyceride diet, modified Atkins diet, and low-glycemic-index treatment have expanded the use of this modality to more children as well as adults. In this review, we discuss our top 10 most pressing research topics related to the ketogenic diet that warrant future study. As well, two promising ketogenic diet clinical researchers discuss their past and current research to help answer some of these questions.

Protective effect of the ketogenic diet in Scn1a mutant mice

PURPOSE

We evaluated the ability of the ketogenic diet (KD) to improve thresholds to flurothyl-induced seizures in two mouse lines with Scn1a mutations: one that models Dravet syndrome (DS) and another that models genetic (generalized) epilepsy with febrile seizures plus (GEFS+).

METHODS

At postnatal day 21, mouse models of DS and GEFS+ were fasted for 12-14 h and then placed on either a 6:1 (fats to proteins and carbohydrates) KD or a standard diet (SD) for 2 weeks. At the end of the 2-week period, we measured thresholds to seizures induced by the chemiconvulsant flurothyl. Body weight, β-hydroxybutyrate (BHB) levels, and glucose levels were also recorded every 2 days over a 2-week period in separate cohorts of mutant and wild-type mice that were either on the KD or the SD.

KEY FINDINGS

Mice on the KD gained less weight and exhibited significantly higher BHB levels compared to mice on the SD. It is notable that thresholds to flurothyl-induced seizures were restored to more normal levels in both mouse lines after 2 weeks on the KD.

SIGNIFICANCE

These results indicate that the KD may be an effective treatment for refractory patients with SCN1A mutations. The availability of mouse models of DS and GEFS+ also provides an opportunity to better understand the mechanism of action of the KD, which may facilitate the development of improved treatments.

Dietary treatments for epilepsy: management guidelines for the general practitioner

As ketogenic diets become more frequently used as a standard treatment for epilepsy in children and adults, hospital and community neurologists, pediatricians, intensivists, general practitioners, and house officers will readily encounter patients who are receiving these dietary treatments. A growing body of evidence demonstrates that dietary therapies for epilepsy (classic ketogenic diet, medium-chain triglyceride diet, modified Atkins diet, and low-glycemic-index treatment) are highly effective, with approximately 30-60% of children overall having at least a 50% reduction in seizures after 6 months of treatment. However, as would be true of any other medical anticonvulsant therapy, these treatments have known side effects and complications requiring recognition and timely action. In addition, the ketogenic diet is a significant intervention requiring rigorous daily adherence; not every family is willing or able to make the necessary commitment to this therapy. We provide herein a survey of the most common situations faced in both the inpatient and outpatient settings, including a discussion of triage and management based on our center's experience as well as the recent 2009 International Consensus Guideline.

A ketogenic diet reduces long-term potentiation in the dentate gyrus of freely behaving rats

Ketogenic diets are very low in carbohydrates and can reduce epileptic seizures significantly. This dietary therapy is particularly effective in pediatric and drug-resistant epilepsy. Hypothesized anticonvulsant mechanisms of ketogenic diets focus on increased inhibition and/or decreased excitability/excitation. Either of these consequences might not only reduce seizures, but also could affect normal brain function and synaptic plasticity. Here, we characterized effects of a ketogenic diet on hippocampal long-term potentiation, a widely studied form of synaptic plasticity. Adult male rats were placed on a control or ketogenic diet for 3 wk before recording. To maintain the most physiological conditions possible, we assessed synaptic transmission and plasticity using chronic in vivo recordings in freely behaving animals. Rats underwent stereotaxic surgery to chronically implant a recording electrode in the hippocampal dentate gyrus and a stimulating electrode in the perforant path; they recovered for 1 wk. After habituation and stable baseline recording, 5-Hz theta-burst stimulation was delivered to induce long-term potentiation. All animals showed successful plasticity, demonstrating that potentiation was not blocked by the ketogenic diet. Compared with rats fed a control diet, rats fed a ketogenic diet demonstrated significantly diminished long-term potentiation. This decreased potentiation lasted for at least 48 h. Reduced potentiation in ketogenic diet-fed rats is consistent with a general increase in neuronal inhibition (or decrease in excitability) and decreased seizure susceptibility. A better understanding of the effects of ketogenic diets on synaptic plasticity and learning is important, as diet-based therapy is often prescribed to children with epilepsy.

Ketogenic diet treatment in adults with refractory epilepsy

The ketogenic diet (KD) is an effective treatment for refractory epilepsy in children. It has been little studied in adults. We evaluated the efficacy of, safety of, and compliance with adjunctive KD treatment in adults with refractory epilepsy in a prospective open-label pilot study. Seizure frequency was evaluated for 4 baseline months, 4 months of adjunctive KD treatment with a 3:1 [fat]:[carbohydrate+protein] weight ratio and 1600 kcal/day, and subsequent elective open-ended KD treatment. A 3:1 ratio was used instead of the 4:1 ratio employed in children because of greater palatability. Average monthly seizure frequency and seizure-free months at baseline were compared with KD months 1-4 (phase 1) and all KD treatment (phase 2). Diet compliance was evaluated with daily urine ketone body and monthly serum β-hydroxybutyrate levels. Twelve subjects were treated for up to 26 months. Three stopped treatment early for psychosocial reasons (n=2) or lack of efficacy. Seven of the 12 subjects were fully compliant, 4 were partially compliant, and 1 was noncompliant. Mean seizure frequency declined by 38.4 and 44.1% for phases 1 and 2, respectively (P=0.04). Forty-two percent and 50% of subjects had a >50% reduction during phases 1 and 2, respectively. Four of 12 subjects (33%) had a >85% seizure reduction. Twenty percent of subject-months were seizure free at baseline versus 56% during both study phases (P=0.04). Adverse effects were mild: nausea, vomiting, diarrhea, constipation, and weight loss.

Ketogenic diets: an historical antiepileptic therapy with promising potentialities for the aging brain

Ketogenic diets (KDs), successfully used in the therapy of paediatric epilepsy for nearly a century, have recently shown beneficial effects also in cancer, obesity, diabetes, GLUT 1 deficiencies, hypoxia-ischemia, traumatic brain injuries, and neurodegeneration. The latter achievement designates aged individuals as optimal recipients, but concerns derive from possible age-dependent differences in KDs effectiveness. Indeed, the main factors influencing ketone bodies utilization by the brain (blood levels, transport mechanisms, catabolic enzymes) undergo developmental changes, although several reports indicate that KDs maintain some efficacy during adulthood and even during advanced aging. Encouraging results obtained in patients affected by age-related neurodegenerative diseases have prompted new interest on KDs' effect on the aging brain, also considering the poor efficacy of therapies currently used. However, recent morphological evidence in synapses of late-adult rats indicates that KDs consequences may be even opposite in different brain regions, likely depending on neuronal vulnerability to age. Thus, further studies are needed to design KDs specifically indicated for single neurodegenerative diseases, and to ameliorate the balance between beneficial and adverse effects in aged subjects. Here we review clinical and experimental data on KDs treatments, focusing on their possible use during pathological aging. Proposed mechanisms of action are also reported and discussed.

Food for thought: the ketogenic diet and adverse effects in children

Early- and Late-Onset Complications of the Ketogenic Diet for Intractable Epilepsy

Kang HC, Chung da E, Kim DW, Kim HD

Epilepsia 2004;45:1116–1123

Purpose

This study was undertaken to evaluate the exact limitations of the ketogenic diet (KD) and to collect data on the prevention and management of its risks.

Methods

Patients (129) who were on the KD from July 1995 to October 2001 at our epilepsy center were assessed in the study. Early-onset (within 4 weeks of the commencement of the KD until stabilization) and late-onset complications (occurring after 4 weeks) were reviewed.

Results

The most common early-onset complication was dehydration, especially in patients who started the KD with initial fasting. Gastrointestinal disturbances, such as nausea/vomiting, diarrhea, and constipation, also were frequently noted, sometimes associated with gastritis and fat intolerance. Other early-onset complications, in order of frequency, were hypertriglyceridemia, transient hyperuricemia, hypercholesterolemia, various infectious diseases, symptomatic hypoglycemia, hypoproteinemia, hypomagnesemia, repetitive hyponatremia, low concentrations of high-density lipoprotein, lipoid pneumonia due to aspiration, hepatitis, acute pancreatitis, and persistent metabolic acidosis. Late-onset complications also included osteopenia, renal stones, cardiomyopathy, secondary hypocarnitinemia, and iron-deficiency anemia. Most early- and late-onset complications were transient and successfully managed by careful follow-up and conservative strategies. However, 22 (17.1%) patients ceased the KD because of various kinds of serious complications, and 4 (3.1%) patients died during the KD, two of sepsis, one of cardiomyopathy, and one of lipoid pneumonia.

Conclusions

Most complications of the KD are transient and can be managed easily with various conservative treatments. However, life-threatening complications should be monitored closely during follow-up.

Purines and the Anti-Epileptic Actions of Ketogenic Diets

Ketogenic diets are high in fat and low in carbohydrates and represent a well-established and effective treatment alternative to anti-epileptic drugs. Ketogenic diets are used for the management of a variety of difficult-to-treat or intractable seizure disorders, especially pediatric refractory epilepsy. However, it has been shown that this dietary therapy can reduce seizures in people of all ages, and ketogenic diets are being applied to other prevalent medical conditions such as diabetes. Although used effectively to treat epilepsy for nearly 90 years, the mechanism(s) by which ketogenic diets work to reduce seizures remain ill-understood. One mechanism receiving increased attention is based on findings that ketogenic diets increase the brain energy molecule ATP, and may also increase the levels and actions of the related endogenous inhibitory neuromodulator adenosine. ATP and adenosine have both been identified as important modulators of seizures; seizures increase the actions of these purines, these purines regulate epileptic activity in brain, adenosine receptor antagonists are pro-convulsant, and adenosinergic mechanisms have been implicated previously in the actions of approved anti-epileptic therapeutics. Here we will review recent literature and describe findings that shed light on mechanistic relationships between ketogenic diets and the purines ATP and adenosine. These emerging mechanisms hold great promise for the effective therapeutic management of epileptic seizures and other neurological conditions.

Effectiveness of the ketogenic diet in a broad range of seizure types and EEG features for severe childhood epilepsies

BACKGROUND

Ketogenic diet (KD) is an effective treatment for pharmacoresistant epilepsy: more than half of the patients show a greater than 50% reduction in seizures.

OBJECTIVE

To identify clinical or electroencephalogram (EEG) variables predicting the response to KD.

METHODS

Clinical and EEG data were retrospectively analysed from 50 consecutive patients treated by KD for severe, pharmacoresistant epilepsy. Most of the patients (70%) had retarded mental and motor development.

RESULTS

Three months after the start of the KD two-thirds (33) of the patients were responders (had a more than 50% reduction in seizure frequency). The presence of epileptiform EEG discharges in the temporal region correlated with an unfavourable response (P = 0.03). The presence of bilateral synchronous epileptiform discharges, and the presence of complex partial seizures approached significance but all other variables did not.

CONCLUSIONS

Our results further support that KD is efficient in a wide variety of epileptic patients with a broad range of EEG features. However, patients with epileptiform discharges in the temporal region are less likely to achieve therapeutic response.

The neuroprotective properties of calorie restriction, the ketogenic diet, and ketone bodies

Both calorie restriction and the ketogenic diet possess broad therapeutic potential in various clinical settings and in various animal models of neurological disease. Following calorie restriction or consumption of a ketogenic diet, there is notable improvement in mitochondrial function, a decrease in the expression of apoptotic and inflammatory mediators and an increase in the activity of neurotrophic factors. However, despite these intriguing observations, it is not yet clear which of these mechanisms account for the observed neuroprotective effects. Furthermore, limited compliance and concern for adverse effects hamper efforts at broader clinical application. Recent research aimed at identifying compounds that can reproduce, at least partially, the neuroprotective effects of the diets with less demanding changes to food intake suggests that ketone bodies might represent an appropriate candidate. Ketone bodies protect neurons against multiple types of neuronal injury and are associated with mitochondrial effects similar to those described during calorie restriction or ketogenic diet treatment. The present review summarizes the neuroprotective effects of calorie restriction, of the ketogenic diet and of ketone bodies, and compares their putative mechanisms of action.

Optimal clinical management of children receiving the ketogenic diet: recommendations of the International Ketogenic Diet Study Group

The ketogenic diet (KD) is an established, effective nonpharmacologic treatment for intractable childhood epilepsy. The KD is provided differently throughout the world, with occasionally significant variations in its administration. There exists a need for more standardized protocols and management recommendations for clinical and research use. In December 2006, The Charlie Foundation commissioned a panel comprised of 26 pediatric epileptologists and dietitians from nine countries with particular expertise using the KD. This group was created in order to create a consensus statement regarding the clinical management of the KD. Subsequently endorsed by the Practice Committee of the Child Neurology Society, this resultant manuscript addresses issues such as patient selection, pre-KD counseling and evaluation, specific dietary therapy selection, implementation, supplementation, follow-up management, adverse event monitoring, and eventual KD discontinuation. This paper highlights recommendations based on best evidence, including areas of agreement and controversy, unanswered questions, and future research.

Ketogenic diet treatment in adults with refractory epilepsy: a prospective pilot study

PURPOSE

To assess the efficacy of ketogenic diet (KD) in adults with refractory epilepsy.

METHODS

Eligible subjects were 18-45 years old with at least two monthly focal seizures (with or without secondary generalization) documented by 8 weeks' follow-up. Classic form of KD treatment (90% fat) was planned for 12 weeks: daily seizure diaries were kept and measurements of the urinary ketones were recorded. Blood studies were done monthly and resting energy expenditure (REE), substrate utilization; body composition and quality of life (QOL) were measured before and after intervention.

RESULTS

Nine patients were enrolled (average age 28+/-6 years; seven women). Only two subjects concluded the study per protocol due to an early drop-out. The average length of KD treatment was 8+/-4 weeks (two patients completed 12 weeks of KD; feelings of hunger and lack of efficacy resulted in withdrawal of the rest). The two patients who concluded the study had a more than 50% reduction in the frequency of the seizures. The others experienced no improvement. Adherence to the KD protocol (100%) was documented by constant ketonuria and increased fat utilization as indicated by the change in respiratory quotient (p<0.031). The KD increased the cholesterol levels (mainly LDL; p=0.0001).

CONCLUSIONS

In our experience with relatively small adult population, adherence to KD is difficult. In patients who had compliance over 3 weeks (6/8), KD does not seem to have a significant effect. Yet, the significant reduction in the two patients who concluded the study per protocol may indicate that some patients may benefit from this diet. Significant increase in LDL levels and the unlikable dietary changes are additional impediments to its implementation among adults with refractory epilepsy.

A pilot trial with modified Atkins' diet in adult patients with refractory epilepsy

OBJECTIVES

At Ghent University Hospital, the feasibility and efficacy of the modified Atkins' diet was evaluated in adult patients with refractory epilepsy. The Atkins' diet restricts carbohydrate intake and was originally designed for weight loss.

PATIENTS AND METHODS

During a 6-month trial period, a carbohydrate restriction of 20 g/day was in place. During a 36 h hospital admission, patients were instructed about the diet. Patients underwent clinical neurological testing, EEG, ECG, blood and urine analyses and mood evaluation before and during the trial. Seizure frequency and side effects were recorded in seizure diaries and followed up at monthly clinic visits.

RESULTS

Eight patients were included in the study. Three out of eight patients followed the diet for 6 months. One out of three patients showed a >50% seizure reduction, 1/3>30%, and 1/3<30%. Side effects such as constipation and diarrhoea were mild and occurred mainly during the initial week of the diet. Patients reported improved concentration and well being. This was confirmed by improved scores on the Beck Depression Inventory Scale.

CONCLUSION

This pilot study shows that the modified Atkins' diet is feasible in an adult population, and that seizure frequency reduction is possible. The results need to be confirmed in larger prospective, controlled studies with comparison groups.

Ketogenic diet prevents cardiac arrest-induced cerebral ischemic neurodegeneration

Ketogenic diet (KD) is an effective treatment for intractable epilepsies. We recently found that KD can prevent seizure and myoclonic jerk in a rat model of post-hypoxic myoclonus. In the present study, we tested the hypothesis that KD can prevent the cerebral ischemic neurodegeneration in this animal model. Rats fed a standard diet or KD for 25 days were being subjected to mechanically induced cardiac arrest brain ischemia for 8 min 30 s. Nine days after cardiac arrest, frozen rat brains were sectioned for evaluation of ischemia-induced neurodegeneration using fluoro-jade (FJ) staining. The FJ positive degenerating neurons were counted manually. Cardiac arrest-induced cerebral ischemia in rats fed the standard diet exhibited extensive neurodegeneration in the CA1 region of the hippocampus, the number of FJ positive neurons was 822+/-80 (n=4). They also showed signs of neurodegeneration in the Purkinje cells of the cerebellum and in the thalamic reticular nucleus, the number of FJ positive neurons in the cerebellum was 55+/-27 (n=4), the number of FJ positive neurons in the thalamic reticular nucleus was 22+/-5 (n=4). In contrast, rats fed KD showed no evidence of neurodegeneration, the number of FJ positive neurons in these areas were zero. The results demonstrate that KD can prevent cardiac arrest-induced cerebral ischemic neurodegeneration in selected brain regions.

[Interest of the ketogenic diet in a refractory status epilepticus in adults]

INTRODUCTION

Ketogenic diets have been employed for the treatment of intractable epilepsy in children since 1921, although underlying mechanism remains unknown.

OBSERVATION

We report the case of a 54-year-old man with partial refractory status epilepticus who exhibited a favourable outcome about seven days after introduction of a ketogenic diet in association with antiepileptic drugs.

DISCUSSION

Although its efficiency was largely demonstrated in children, little is known about the impact of a ketogenic diet in adults with refractory epilepsy.

CONCLUSION

Introduction of a ketogenic diet requires a multidisciplinary approach. Its usefulness in adult intractable epilepsy and/or refractory status epilepticus merits further study into its efficacy in reducing the frequency of seizures and a possible prolonged effect.

Effect of Short-Term Ketogenic Diet on Redox Status of Human Blood

The present study investigated the effect of a ketogenic diet on the blood redox status of healthy female subjects. Twenty healthy females with mean body mass index of 21.45 +/- 2.05 kg/m(2) were provided a low-carbohydrate (55 +/- 6 g; 13% total energy), high-fat (138 +/- 16 g; 74% total energy), calorie-restricted (-465 +/- 115 kcal/d) diet. The followings were tested prior to and after 14 days consumption of the diet: Whole body, body weight and total body fat; blood, complete blood count, red blood cells, white blood cells, hemoglobin, and hematocrit; plasma, 3-beta-hydroxybutyrate, total antioxidative status, and uric acid; red blood cells, total sulfhydryl content, malondialdehyde, superoxide dismutase activity, and catalase activity. After 14 days, weight loss was significant whereas no changes were detected in body fat. No alterations were observed in blood count or morphology. 3-beta-hydroxybutyrate, total antioxidative status, uric acid, and sulfhydryl content were significantly increased. There were no alterations in malondialdehyde, or superoxide dismutase or catalase activity. The present study demonstrates that 14 days of a ketogenic diet elevates blood antioxidative capacity and does not induce oxidative stress in healthy subjects.

Anticonvulsant mechanisms of the ketogenic diet

The ketogenic diet (KD) is a broadly effective treatment for medically refractory epilepsy. Despite nearly a century of use, the mechanisms underlying its clinical efficacy remain unknown. In this review, we present one intersecting view of how the KD may exert its anticonvulsant activity against the backdrop of several seemingly disparate mechanistic theories. We summarize key insights gleaned from experimental and clinical studies of the KD, and focus particular attention on the role that ketone bodies, fatty acids, and limited glucose may play in seizure control. Chronic ketosis is anticipated to modify the tricarboxcylic acid cycle to increase GABA synthesis in brain, limit reactive oxygen species (ROS) generation, and boost energy production in brain tissue. Among several direct neuro-inhibitory actions, polyunsaturated fatty acids increased after KD induce the expression of neuronal uncoupling proteins (UCPs), a collective up-regulation of numerous energy metabolism genes, and mitochondrial biogenesis. These effects further limit ROS generation and increase energy production. As a result of limited glucose and enhanced oxidative phosphorylation, reduced glycolytic flux is hypothesized to activate metabolic K(ATP) channels and hyperpolarize neurons and/or glia. Although it is unlikely that a single mechanism, however well substantiated, will explain all of the diet's clinical benefits, these diverse, coordinated changes seem poised to stabilize synaptic function and increase the resistance to seizures throughout the brain.

Clinical aspects of the ketogenic diet

The ketogenic diet remains a valuable therapeutic option for patients with intractable epilepsy. Clinical aspects of the diet's success may provide insights into epileptogenesis and anticonvulsant action. The diet's efficacy has been established primarily through large case series. The diet has been used successfully in patients with many different epilepsy syndromes in countries around the world. Potential adverse effects can be avoided with careful attention during the diet's initiation and maintenance phases. In the last decade, variations to the classical ketogenic diet have been utilized. Ketogenic diets now are being used for diseases other than epilepsy. This critical analysis of the diet should provide the impetus for further clinical and basic research into the diet's application and mechanisms of action.

The ketogenic diet: one decade later

The ketogenic diet, a high fat, adequate protein, low carbohydrate diet, has, during the past decade, had a resurgence of interest for the treatment of difficult-to-control seizures in children. This review traces its history, reviews its uses and side effects, and discusses possible alternatives and the diet's possible mechanisms of action. Finally, this review looks toward possible future uses of the ketogenic diet for conditions other than epilepsy.

Mitochondrial biogenesis in the anticonvulsant mechanism of the ketogenic diet

OBJECTIVE

The full anticonvulsant effect of the ketogenic diet (KD) can require weeks to develop in rats, suggesting that altered gene expression is involved. The KD typically is used in pediatric epilepsies, but is effective also in adolescents and adults. Our goal was to use microarray and complementary technologies in adolescent rats to understand its anticonvulsant effect.

METHODS

Microarrays were used to define patterns of gene expression in the hippocampus of rats fed a KD or control diet for 3 weeks. Hippocampi from control- and KD-fed rats were also compared for the number of mitochondrial profiles in electron micrographs, the levels of selected energy metabolites and enzyme activities, and the effect of low glucose on synaptic transmission.

RESULTS

Most striking was a coordinated upregulation of all (n = 34) differentially regulated transcripts encoding energy metabolism enzymes and 39 of 42 transcripts encoding mitochondrial proteins, which was accompanied by an increased number of mitochondrial profiles, a higher phosphocreatine/creatine ratio, elevated glutamate levels, and decreased glycogen levels. Consistent with increased energy reserves, synaptic transmission in hippocampal slices from KD-fed animals was resistant to low glucose.

INTERPRETATION

These data show that a calorie-restricted KD enhances brain metabolism. We propose an anticonvulsant mechanism of the KD involving mitochondrial biogenesis leading to enhanced alternative energy stores.

The oral glucose tolerance test is frequently abnormal in patients with uncontrolled epilepsy

PURPOSE

The clinical efficacy of the ketogenic diet as therapy for patients with difficult-to-treat epilepsy prompted us to investigate the glucose metabolism of these patients under an oral overload of glucose, that is, in the oral glucose tolerance test (OGTT).

METHODS

Thirty patients (12 males, 18 females; age range: 17-59, mean: 35.1) with difficult-to-treat epilepsy, 23 patients with controlled epilepsy (11 males, 12 females; age range: 14-66, mean: 36.9), and 39 control subjects (18 males, 21 females; age range: 16-58, mean: 33.3) were evaluated with the OGTT. For patients with epilepsy, we also measured C-peptide and glycosylated hemoglobin in the fasting state. Glucose levels lower than 70 mg/dL at any point of the curve were considered to be abnormal.

RESULTS

All subjects in the control group and the group with controlled epilepsy had a normal OGTT. In contrast, all 30 patients with difficult-to-treat epilepsy had at least one point on the OGTT curve below the normal range (P<0.001), most often 180 and 240 minutes after the oral glucose load (P<0.001). C-peptide levels were significantly lower in the group with difficult-to-treat epilepsy as compared with the group with controlled epilepsy. Fasting glycohemoglobin and insulin levels did not differ between the two patient groups.

CONCLUSIONS

We suggest that undiagnosed metabolic disturbances in patients with difficult-to-treat epilepsy may somehow contribute to their refractoriness to conventional pharmacological therapy. We propose the hypothesis that calorie-restricted diets aimed at correcting OGTT curves may prove beneficial in treating patients with difficult-to-treat epilepsy. Our hypothesis generates a clear endpoint for the diet, and its demonstration would provide new standards for diet-based antiepileptic regimens. Accordingly, our results may help in understanding the positive consequences of ketogenic or calorie-restricted diets in persons with seizures.

State of the ketogenic diet(s) in epilepsy

Fasting has been recognized as a treatment for seizures since ancient times. The ketogenic diet is a low-carbohydrate, adequate-protein, high-fat diet that biochemically mimics the fasting state and has been used to successfully treat seizures for 85 years. The diet has enjoyed a resurgence in popularity over the past decade and is gaining acceptance and use worldwide. Many studies over the past several years have explored possible mechanisms of action for the ketogenic diet. This review addresses these studies, as well as recent research regarding possible indications for the diet, variations in its initiation, side effect profiles, and the recent use of modified formulations to improve tolerability.

The ketogenic diet causes a reversible decrease in activity level in Long-Evans rats

Individuals with epilepsy also often exhibit symptoms of attention deficit hyperactivity disorder (ADHD). The ketogenic diet, which is a high fat, low protein, and low carbohydrate diet used in the treatment of intractable epilepsy, also appears to improve symptoms of ADHD in individuals with both disorders. Previous research suggests that the diet decreases the activity level of rats. The purpose of the present research was to further investigate the effects of the ketogenic diet on activity level, using an animal model. Two experiments were conducted. The first experiment examined the time frame and reversibility of the effect of the diet on activity level. The second experiment examined the relationship between activity level and anxiety level. In both experiments, adult male Long-Evans rats were placed on either a ketogenic diet or a control diet. The results of the first experiment show that the ketogenic diet can cause a decrease in activity level within 24 h and that the results are reversible. The results of Experiment 2 show that the decrease in activity level is not linked to a change in anxiety level. The ketogenic diet may be of use in the treatment of ADHD.