Study of the ketogenic agent AC-1202 in mild to moderate Alzheimer's disease: a randomized, double-blind, placebo-controlled, multicenter trial

Symptomatic and nonamyloid/tau based pharmacologic treatment for Alzheimer disease

In this work we consider marketed drugs for Alzheimer disease (AD) including acetylcholinesterase inhibitors (AChE-Is) and antiglutamatergic treatment involving the N-methyl-d-aspartate (NMDA) receptor. We discuss medications and substances available for use as cognitive enhancers that are not approved for AD or cognitive impairment, and other neurotransmitter-related therapies in development or currently being researched. We also review putative therapies that aim to slow disease progression by mechanisms not directly related to amyloid or tau.

Use of medical foods and nutritional approaches in the treatment of Alzheimer's disease

Alzheimer's disease, the most common cause of dementia, has a high global economic impact. To date, there is no curative treatment; therefore, many efforts are directed not only at novel potential disease-modifying treatments and interventions, but also to develop alternative symptomatic and supportive treatments. Examples of these efforts include the medical foods. There are three medical foods that claim to offer symptomatic benefits: Axona(®), Souvenaid(®) and CerefolinNAC(®). Axona supplies ketone bodies as alternative energy source to neurons. Souvenaid provides precursors thought to enhance synaptic function. CerefolinNAC addresses the role of oxidative stress related to memory loss. The current scientific evidence on these medical foods is reviewed in this article. Furthermore, we also review the concept and evidence supporting use of the Mediterranean diet, a possible alternative to medical foods that, if implemented correctly, may have lower costs, fewer side effects and stronger epidemiological health outcomes.

Mitochondrial biogenesis and increased uncoupling protein 1 in brown adipose tissue of mice fed a ketone ester diet

We measured the effects of a diet in which D-β-hydroxybutyrate-(R)-1,3 butanediol monoester [ketone ester (KE)] replaced equicaloric amounts of carbohydrate on 8-wk-old male C57BL/6J mice. Diets contained equal amounts of fat, protein, and micronutrients. The KE group was fed ad libitum, whereas the control (Ctrl) mice were pair-fed to the KE group. Blood d-β-hydroxybutyrate levels in the KE group were 3-5 times those reported with high-fat ketogenic diets. Voluntary food intake was reduced dose dependently with the KE diet. Feeding the KE diet for up to 1 mo increased the number of mitochondria and doubled the electron transport chain proteins, uncoupling protein 1, and mitochondrial biogenesis-regulating proteins in the interscapular brown adipose tissue (IBAT). [(18)F]-Fluorodeoxyglucose uptake in IBAT of the KE group was twice that in IBAT of the Ctrl group. Plasma leptin levels of the KE group were more than 2-fold those of the Ctrl group and were associated with increased sympathetic nervous system activity to IBAT. The KE group exhibited 14% greater resting energy expenditure, but the total energy expenditure measured over a 24-h period or body weights was not different. The quantitative insulin-sensitivity check index was 73% higher in the KE group. These results identify KE as a potential antiobesity supplement.

Ketone bodies in epilepsy

Seizures that are resistant to standard medications remain a major clinical problem. One underutilized option for patients with medication-resistant seizures is the high-fat, low-carbohydrate ketogenic diet. The diet received its name based on the observation that patients consuming this diet produce ketone bodies (e.g., acetoacetate, β-hydroxybutyrate, and acetone). Although the exact mechanisms of the diet are unknown, ketone bodies have been hypothesized to contribute to the anticonvulsant and antiepileptic effects. In this review, anticonvulsant properties of ketone bodies and the ketogenic diet are discussed (including GABAergic and glutamatergic effects). Because of the importance of ketone body metabolism in the early stages of life, the effects of ketone bodies on developing neurons in vitro also are discussed. Understanding how ketone bodies exert their effects will help optimize their use in treating epilepsy and other neurological disorders.

Mitochondrial abnormalities in Alzheimer's disease: possible targets for therapeutic intervention

Mitochondria from persons with Alzheimer's disease (AD) differ from those of age-matched control subjects. Differences in mitochondrial morphology and function are well documented, and are not brain-limited. Some of these differences are present during all stages of AD, and are even seen in individuals who are without AD symptoms and signs but who have an increased risk of developing AD. This chapter considers the status of mitochondria in AD subjects, the potential basis for AD subject mitochondrial perturbations, and the implications of these perturbations. Data from multiple lines of investigation, including epidemiologic, biochemical, molecular, and cytoplasmic hybrid studies, are reviewed. The possibility that mitochondria could potentially constitute a reasonable AD therapeutic target is discussed, as are several potential mitochondrial medicine treatment strategies.

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.

Dietary omega 3 polyunsaturated fatty acids and Alzheimer's disease: interaction with apolipoprotein E genotype

Epidemiological studies suggest a protective role of omega-3 poly-unsaturated fatty acids (n-3 PUFA) against Alzheimer's disease (AD). However, most intervention studies of supplementation with n-3 PUFA have yielded disappointing results. One reason for such discordant results may result from inadequate targeting of individuals who might benefit from the supplementation, in particular because of their genetic susceptibility to AD. The ε4 allele of the apolipoprotein E gene (ApoE) is a genetic risk factor for late-onset AD. ApoE plays a key role in the transport of cholesterol and other lipids involved in brain composition and functioning. The action of n-3 PUFA on the aging brain might therefore differ according to ApoE polymorphism. The aim of this review is to examine the interaction between dietary fatty acids and ApoE genotype on the risk for AD. Carriers of the ε4 allele tend to be the most responsive to changes in dietary fat and cholesterol. Conversely, several epidemiological studies suggest a protective effect of long-chain n-3 PUFA on cognitive decline only in those who do not carry ε4 but with inconsistent results. An intervention study showed that only non-carriers had increased concentrations of long-chain n-3 PUFA in response to supplementation. The mechanisms underlying this gene-by-diet interaction on AD risk may involve impaired fatty acids and cholesterol transport, altered metabolism of n-3 PUFA, glucose or ketones, or modification of other risk factors of AD in ε4 carriers. Further research is needed to explain the differential effect of n-3 PUFA on AD according to ApoE genotype.

Pharmacogenetic analysis of the effects of polymorphisms in APOE, IDE and IL1B on a ketone body based therapeutic on cognition in mild to moderate Alzheimer's disease; a randomized, double-blind, placebo-controlled study

Background

To examine the effect of genetic variation in APOE, IDE and IL1B on the response to induced ketosis in the Alzheimer's Disease Assessment Scale-Cognitive subscale (ADAS-Cog) in subjects with mild to moderate Alzheimer's disease (AD).

Methods

Genotype effects on ADAS-Cog scores from a randomized, double-blind, placebo-controlled study in mild to moderate AD were examined by an overall two way analysis of variance. In addition, interactions with the carriage status of the epsilon 4 allele of the APOE gene (APOE4) were examined.

Results

Significant differences in response to induced ketosis were found among non-carriers of putative gain-of-function polymorphisms in rs1143627 and rs16944 in the IL1B gene and among variants of the polymorphism rs2251101 in the IDE gene. Significant differences were found among non-carriers of the APOE4 gene, with notable improvement among the E3/E3 genotype group.

Conclusions

Variants in APOE, IL1B and IDE may influence the cognitive response to induced ketosis in patients with mild to moderate AD.

Trial registration

This trial was registered with ClinicalTrials.gov, registry number NCT00142805.

Metabolic treatments for intractable epilepsy

When a child on anticonvulsant medications continues to have seizures, what other options should be considered? Over the past 100 years, dietary therapies for the treatment of intractable epilepsy have become more widely recognized, and their use has continued to expand throughout the world. An increasing number of studies has shown efficacy of these metabolic treatments in improving seizure control. Currently, 4 types of dietary therapy are available in the clinic: the classic long chain fatty acid "ketogenic" diet, the medium chain triglyceride diet, the modified Atkins diet, and the low glycemic index treatment. These therapies should be considered earlier in the treatment of intractable epilepsy because they offer a different approach to treatment that has proven efficacious, tolerable, and cost-effective.

Neuroprotection in metabolism-based therapy

Metabolism-based therapy has been used successfully in the treatment of seizures but study of its use in other neurodegenerative disorders is growing. Data demonstrating the use of different forms of metabolism-based therapy in human trials of Alzheimer disease and Parkinson disease are discussed. Animal and in vitro studies have shed light on metabolism-based therapy's mechanisms in these diseases, as well as ALS, aging, ischemia, trauma and mitochondrial cytopathies. Additional insights may be obtained by considering the role of metabolism-based therapy in cell disability and death (specifically apoptosis, excitotoxicity, and autophagy).

Role and treatment of mitochondrial DNA-related mitochondrial dysfunction in sporadic neurodegenerative diseases

Several sporadic neurodegenerative diseases display phenomena that directly or indirectly relate to mitochondrial function. Data suggesting altered mitochondrial function in these diseases could arise from mitochondrial DNA (mtDNA) are reviewed. Approaches for manipulating mitochondrial function and minimizing the downstream consequences of mitochondrial dysfunction are discussed.

Brain fuel metabolism, aging, and Alzheimer's disease

Lower brain glucose metabolism is present before the onset of clinically measurable cognitive decline in two groups of people at risk of Alzheimer's disease--carriers of apolipoprotein E4, and in those with a maternal family history of AD. Supported by emerging evidence from in vitro and animal studies, these reports suggest that brain hypometabolism may precede and therefore contribute to the neuropathologic cascade leading to cognitive decline in AD. The reason brain hypometabolism develops is unclear but may include defects in brain glucose transport, disrupted glycolysis, and/or impaired mitochondrial function. Methodologic issues presently preclude knowing with certainty whether or not aging in the absence of cognitive impairment is necessarily associated with lower brain glucose metabolism. Nevertheless, aging appears to increase the risk of deteriorating systemic control of glucose utilization, which, in turn, may increase the risk of declining brain glucose uptake, at least in some brain regions. A contributing role of deteriorating glucose availability to or metabolism by the brain in AD does not exclude the opposite effect, i.e., that neurodegenerative processes in AD further decrease brain glucose metabolism because of reduced synaptic functionality and hence reduced energy needs, thereby completing a vicious cycle. Strategies to reduce the risk of AD by breaking this cycle should aim to (1) improve insulin sensitivity by improving systemic glucose utilization, or (2) bypass deteriorating brain glucose metabolism using approaches that safely induce mild, sustainable ketonemia.

Dietary ketosis enhances memory in mild cognitive impairment

We randomly assigned 23 older adults with mild cognitive impairment to either a high carbohydrate or very low carbohydrate diet. Following the 6-week intervention period, we observed improved verbal memory performance for the low carbohydrate subjects (p = 0.01) as well as reductions in weight (p < 0.0001), waist circumference (p < 0.0001), fasting glucose (p = 0.009), and fasting insulin (p = 0.005). Level of depressive symptoms was not affected. Change in calorie intake, insulin level, and weight were not correlated with memory performance for the entire sample, although a trend toward a moderate relationship between insulin and memory was observed within the low carbohydrate group. Ketone levels were positively correlated with memory performance (p = 0.04). These findings indicate that very low carbohydrate consumption, even in the short term, can improve memory function in older adults with increased risk for Alzheimer's disease. While this effect may be attributable in part to correction of hyperinsulinemia, other mechanisms associated with ketosis such as reduced inflammation and enhanced energy metabolism also may have contributed to improved neurocognitive function. Further investigation of this intervention is warranted to evaluate its preventive potential and mechanisms of action in the context of early neurodegeneration.

Bezafibrate mildly stimulates ketogenesis and fatty acid metabolism in hypertriglyceridemic subjects

Our objective was to determine whether bezafibrate, a hypotriglyceridemic drug and peroxisome proliferator-activated receptor (PPAR)-alpha agonist, is ketogenic and increases fatty acid oxidation in humans. We measured fatty acid metabolism and ketone levels in 13 mildly hypertriglycemic adults (67 +/- 11 years old) during 2 metabolic study days lasting 6 h, 1 day before and 1 day after bezafibrate (400 mg of bezafibrate per day for 12 weeks). beta-Hydroxybutyrate, triglycerides, free fatty acids, fatty acid profiles, insulin, and glucose were measured in plasma, and fatty acid beta-oxidation was measured in breath after an oral 50-mg dose of the fatty acid tracer [U-(13)C]linoleic acid. As expected, 12 weeks on bezafibrate decreased plasma triglycerides by 35%. Bezafibrate tended to raise postprandial beta-hydroxybutyrate, an effect that was significant after normalization to the fasting baseline values (p = 0.03). beta-Oxidation of [U-(13)C]linoleic acid increased by 30% (p = 0.03) after treatment. On the metabolic study day after bezafibrate treatment, postprandial insulin decreased by 26% (p = 0.01), and glucose concentrations were lower 2 to 5 h postprandially. Thus, in hypertriglyceridemic individuals, bezafibrate is mildly ketogenic and significantly changes fatty acid metabolism, effects that may be linked to PPARalpha stimulation and to moderately improved glucose metabolism.

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.

Current therapeutic targets for the treatment of Alzheimer's disease

Alzheimer's disease is a progressive neurodegenerative disease for which no cure exists. There is a substantial need for new therapies that offer improved symptomatic benefit and disease-slowing capabilities. In recent decades there has been substantial progress in understanding the molecular and cellular changes associated with Alzheimer's disease pathology. This has resulted in identification of a large number of new drug targets. These targets include, but are not limited to, therapies that aim to prevent production of or remove the amyloid-beta protein that accumulates in neuritic plaques; to prevent the hyperphosphorylation and aggregation into paired helical filaments of the microtubule-associated protein tau; and to keep neurons alive and functioning normally in the face of these pathologic challenges. We provide a review of these targets for drug development.

Ketones prevent synaptic dysfunction induced by mitochondrial respiratory complex inhibitors

Ketones have previously shown beneficial effects in models of neurodegenerative disorders, particularly against associated mitochondrial dysfunction and cognitive impairment. However, evidence of a synaptic protective effect of ketones remains lacking. We tested the effects of ketones on synaptic impairment induced by mitochondrial respiratory complex (MRC) inhibitors using electrophysiological, reactive oxygen species (ROS) imaging and biochemical techniques. MRC inhibitors dose-dependently suppressed both population spike (PS) and field potential amplitudes in the CA1 hippocampus. Pre-treatment with ketones strongly prevented changes in the PS, whereas partial protection was seen in the field potential. Rotenone (Rot; 100 nmol/L), a MRC I inhibitor, suppressed synaptic function without altering ROS levels and PS depression by Rot was unaffected by antioxidants. In contrast, antioxidant-induced PS recovery against the MRC II inhibitor 3-nitropropionic acid (3-NP; 1 mmol/L) was similar to the synaptic protective effects of ketones. Ketones also suppressed ROS generation induced by 3-NP. Finally, ketones reversed the decreases in ATP levels caused by Rot and 3-NP. In summary, our data demonstrate that ketones can preserve synaptic function in CA1 hippocampus induced by MRC dysfunction, likely through an antioxidant action and enhanced ATP generation.

The Alzheimer's disease mitochondrial cascade hypothesis

We first proposed the mitochondrial cascade hypothesis of sporadic Alzheimer's disease (AD) in 2004. Our core assumptions were a person's genes determine baseline mitochondrial function and durability, this durability determines how mitochondria change with advancing age, and critical changes in mitochondrial function initiate other pathologies characteristic of AD. Since then several lines of investigation report data consistent with or supportive of our hypothesis. In particular, AD endophenotype studies suggest a strong maternal genetic contribution, and links between mitochondrial function, tau phosphorylation, and amyloid-beta (Abeta) amyloidosis are increasingly recognized. As predicted, AD therapies designed to reduce Abeta thus far have had at best very limited clinical benefits; our hypothesis identifies alternative therapeutic targets. While placing mitochondria at the apex of an AD cascade certainly remains controversial, it is increasingly accepted by the AD research community that mitochondria play an important role in the late-onset forms of the disease. Even if the mitochondrial cascade hypothesis proves incorrect, considering its assumptions could potentially advance our understanding of sporadic, late-onset AD.

Mitochondrial Medicine and the Neurodegenerative Mitochondriopathies

Neurodegenerative diseases are a common late-life scourge for which disease-modifying treatments are sorely needed. Mitochondrial perturbation is commonly observed in these diseases, so pursuing treatment development strategies that target mitochondria or processes affected by mitochondria seems reasonable. This review discusses the rationale underlying past and current efforts to treat neurodegenerative diseases using mitochondrial medicine, and tries to predict how future efforts might proceed.