Induction of ketosis may improve mitochondrial function and decrease steady-state amyloid-β precursor protein (APP) levels in the aged dog

Role of ketogenic diet in neurodegenerative diseases focusing on Alzheimer diseases: The guardian angle

The ketogenic diet (KD) is a low-carbohydrate, adequate protein and high-fat diet. KD is primarily used to treat refractory epilepsy. KD was shown to be effective in treating different neurodegenerative diseases. Alzheimer disease (AD) is the first common neurodegenerative disease in the world characterized by memory and cognitive impairment. However, the underlying mechanism of KD in controlling of AD and other neurodegenerative diseases are not discussed widely. Therefore, this review aims to revise the fundamental mechanism of KD in different neurodegenerative diseases focusing on the AD. KD induces a fasting-like which modulates the central and peripheral metabolism by regulating mitochondrial dysfunction, oxidative stress, inflammation, gut-flora, and autophagy in different neurodegenerative diseases. Different studies highlighted that KD improves AD neuropathology by regulating synaptic neurotransmission and inhibiting of neuroinflammation and oxidative stress. In conclusion, KD improves cognitive function and attenuates the progression of AD neuropathology by reducing oxidative stress, mitochondrial dysfunction, and enhancing neuronal autophagy and brain BDNF.

Nutrition and Aging in Dogs and Cats

Aging is often associated with chronic inflammation and declining health. Both veterinarians and owners of aging dogs and cats are interested in nutritional solutions and strategies to prevent signs of age-related disease, increase longevity, and improve quality of life. Physiological decreases in muscle mass, decreased immunity, and a decrease in sense acuity are some of the changes often seen in otherwise healthy senior pets; however, there may also be an increase in risk for pathologies such as renal, cardiovascular, musculoskeletal, and neoplastic diseases. Aging may also lead to cognitive decline and even cognitive dysfunction. Some nutritional strategies that may be helpful with the prevention and treatment of age-related diseases include supplementation with ω3 polyunsaturated fatty acids and antioxidant nutrients that can help modulate inflammation and benefit osteoarthritis, renal disease, cancer, and more. Supplementation with medium-chain triglycerides shows promise in the treatment of canine cognitive dysfunction as these may be metabolized to ketone bodies that are utilized as an alternative energy source for the central nervous system. Additionally, a high intake of dietary phosphorus in soluble and bioavailable forms can lead to renal disease, which is of greater concern in senior pets. There are no published guidelines for nutritional requirements specific to senior pets and as a result, products marketed for senior dogs and cats are highly variable.

The Effects of Medium Chain Triglyceride for Alzheimer's Disease Related Cognitive Impairment: A Systematic Review and Meta-Analysis

BACKGROUND

The current lack of effective drug therapies for Alzheimer's disease (AD) has prompted researchers to seek alternative nutritional therapies, such as medium chain triglycerides (MCTs). However, results are inconclusive.

OBJECTIVE

This systematic review and meta-analysis aims to summarize current evidence on the effect of MCT on cognitive function in patients with mild cognitive impairment (MCI) or AD.

METHODS

A systematic search was conducted up until December 16, 2022, to identify human interventions reporting the effects of MCT on cognitive functioning of MCI or AD patients. 995 non-duplicated publications were identified, of which nine (n = 10 studies) met the inclusion criteria.

RESULTS

Meta-analysis showed cognitive improvements in general (SMD = 0.64; 95% CI [0.05, 1.24]), but not in memory, language, and attention domains after oral MCT administration, compared to placebo. The effect of MCT was greater among APOEɛ4 (-) subjects than APOEɛ4 (+) subjects (SMD = 1.87; 95% CI [0.35, 3.40]).

CONCLUSION

This review provides some evidence that treatment with MCT could improve general cognitive function in APOEɛ4 (-) cognitive impaired patients. Better characterized clinical studies are warranted before making a definitive conclusion on the use of MCT for MCI and AD management.

The Role of Ketogenic Diet in the Treatment of Neurological Diseases

Over a hundred years of study on the favourable effect of ketogenic diets in the treatment of epilepsy have contributed to a long-lasting discussion on its potential influence on other neurological diseases. A significant increase in the number of scientific studies in that field has been currently observed. The aim of this paper is a widespread, thorough analysis of the available scientific evidence in respect of the role of the ketogenic diet in the therapy of neurological diseases such as: epilepsy, Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS) and migraine. A wide range of the mechanisms of action of the ketogenic diet has been demonstrated in neurological diseases, including, among other effects, its influence on the reduction in inflammatory conditions and the amount of reactive oxygen species (ROS), the restoration of the myelin sheath of the neurons, the formation and regeneration of mitochondria, neuronal metabolism, the provision of an alternative source of energy for neurons (ketone bodies), the reduction in glucose and insulin concentrations, the reduction in amyloid plaques, the induction of autophagy, the alleviation of microglia activation, the reduction in excessive neuronal activation, the modulation of intestinal microbiota, the expression of genes, dopamine production and the increase in glutamine conversion into GABA. The studies discussed (including randomised controlled studies), conducted in neurological patients, have stressed the effectiveness of the ketogenic diet in the treatment of epilepsy and have demonstrated its promising therapeutic potential in Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS) and migraine. A frequent advantage of the diet was demonstrated over non-ketogenic diets (in the control groups) in the therapy of neurological diseases, with simultaneous safety and feasibility when conducting the nutritional model.

Ketogenic Diet: An Effective Treatment Approach for Neurodegenerative Diseases

This review discusses the effects and mechanisms of a ketogenic diet on neurodegenerative diseases on the basis of available evidence. A ketogenic diet refers to a high-fat, mediumprotein, and low-carbohydrate diet that leads to a metabolic shift to ketosis. This review systematically summarizes the scientific literature supporting this effective treatment approach for neurodegenerative diseases, including effects on mitochondrial function, oxidative stress, neuronal apoptosis, neuroinflammation, and the microbiota-gut-brain axis. It also highlights the clinical evidence for the effects of the ketogenic diet in the treatment of Alzheimer's disease, Parkinson's disease, and motor neuron disease. Finally, it discusses the common adverse effects of ketogenic therapy. Although the complete mechanism of the ketogenic diet in the treatment of neurodegenerative diseases remains to be elucidated, its clinical efficacy has attracted many new followers. The ketogenic diet is a good candidate for adjuvant therapy, but its specific applicability depends on the type and the degree of the disease.

Sphingolipids and DHA Improve Cognitive Deficits in Aged Beagle Dogs

Canine cognitive dysfunction syndrome (CDS) is a disorder found in senior dogs that is typically defined by the development of specific behavioral signs which are attributed to pathological brain aging and no other medical causes. One way of objectively characterizing CDS is with the use of validated neuropsychological test batteries in aged Beagle dogs, which are a natural model of this condition. This study used a series of neuropsychological tests to evaluate the effectiveness of supplementation with a novel lipid extract containing porcine brain-derived sphingolipids (Biosfeen®) and docosahexaenoic acid (DHA) for attenuating cognitive deficits in aged Beagles. Two groups (n = 12), balanced for baseline cognitive test performance, received a daily oral dose of either test supplement, or placebo over a 6-month treatment phase. Cognitive function was evaluated using the following tasks: delayed non-matching to position (DNMP), selective attention, discrimination learning retention, discrimination reversal learning, and spatial discrimination acquisition and reversal learning. The effect of the supplement on brain metabolism using magnetic resonance spectroscopy (MRS) was also examined. A significant decline (p = 0.02) in DNMP performance was seen in placebo-treated dogs, but not in dogs receiving the supplement, suggesting attenuation of working memory performance decline. Compared to placebo, the supplemented group also demonstrated significantly improved (p = 0.01) performance on the most difficult pattern of the spatial discrimination task and on reversal learning of the same pattern (p = 0.01), potentially reflecting improved spatial recognition and executive function, respectively. MRS revealed a significant increase (p = 0.048) in frontal lobe glutamate and glutamine in the treatment group compared to placebo, indicating a physiological change which may be attributed to the supplement. Decreased levels of glutamate and glutamine have been correlated with cognitive decline, suggesting the observed increase in these metabolites might be linked to the positive cognitive effects found in the present study. Results of this study suggest the novel lipid extract may be beneficial for counteracting age-dependent deficits in Beagle dogs and supports further investigation into its use for treatment of CDS. Additionally, due to parallels between canine and human aging, these results might also have applicability for the use of the supplement in human cognitive health.

The Combined Influences of Exercise, Diet and Sleep on Neuroplasticity

Neuroplasticity refers to the brain’s ability to undergo structural and functional adaptations in response to experience, and this process is associated with learning, memory and improvements in cognitive function. The brain’s propensity for neuroplasticity is influenced by lifestyle factors including exercise, diet and sleep. This review gathers evidence from molecular, systems and behavioral neuroscience to explain how these three key lifestyle factors influence neuroplasticity alone and in combination with one another. This review collected results from human studies as well as animal models. This information will have implications for research, educational, fitness and neurorehabilitation settings.

Ketogenic diet for human diseases: the underlying mechanisms and potential for clinical implementations

The ketogenic diet (KD) is a high-fat, adequate-protein, and very-low-carbohydrate diet regimen that mimics the metabolism of the fasting state to induce the production of ketone bodies. The KD has long been established as a remarkably successful dietary approach for the treatment of intractable epilepsy and has increasingly garnered research attention rapidly in the past decade, subject to emerging evidence of the promising therapeutic potential of the KD for various diseases, besides epilepsy, from obesity to malignancies. In this review, we summarize the experimental and/or clinical evidence of the efficacy and safety of the KD in different diseases, and discuss the possible mechanisms of action based on recent advances in understanding the influence of the KD at the cellular and molecular levels. We emphasize that the KD may function through multiple mechanisms, which remain to be further elucidated. The challenges and future directions for the clinical implementation of the KD in the treatment of a spectrum of diseases have been discussed. We suggest that, with encouraging evidence of therapeutic effects and increasing insights into the mechanisms of action, randomized controlled trials should be conducted to elucidate a foundation for the clinical use of the KD.

The Impact of Medium Chain and Polyunsaturated ω-3-Fatty Acids on Amyloid-β Deposition, Oxidative Stress and Metabolic Dysfunction Associated with Alzheimer's Disease

Alzheimer’s disease (AD), the most common cause of dementia in the elderly population, is closely linked to a dysregulated cerebral lipid homeostasis and particular changes in brain fatty acid (FA) composition. The abnormal extracellular accumulation and deposition of the peptide amyloid-β (Aβ) is considered as an early toxic event in AD pathogenesis, which initiates a series of events leading to neuronal dysfunction and death. These include the induction of neuroinflammation and oxidative stress, the disruption of calcium homeostasis and membrane integrity, an impairment of cerebral energy metabolism, as well as synaptic and mitochondrial dysfunction. Dietary medium chain fatty acids (MCFAs) and polyunsaturated ω-3-fatty acids (ω-3-PUFAs) seem to be valuable for disease modification. Both classes of FAs have neuronal health-promoting and cognition-enhancing properties and might be of benefit for patients suffering from mild cognitive impairment (MCI) and AD. This review summarizes the current knowledge about the molecular mechanisms by which MCFAs and ω-3-PUFAs reduce the cerebral Aβ deposition, improve brain energy metabolism, and lessen oxidative stress levels.

Dietary Regulation of Gut-Brain Axis in Alzheimer's Disease: Importance of Microbiota Metabolites

Alzheimer's disease (AD) is a neurodegenerative disease that impacts 45 million people worldwide and is ranked as the 6th top cause of death among all adults by the Centers for Disease Control and Prevention. While genetics is an important risk factor for the development of AD, environment and lifestyle are also contributing risk factors. One such environmental factor is diet, which has emerged as a key influencer of AD development/progression as well as cognition. Diets containing large quantities of saturated/trans-fats, refined carbohydrates, limited intake of fiber, and alcohol are associated with cognitive dysfunction while conversely diets low in saturated/trans-fats (i.e., bad fats), high mono/polyunsaturated fats (i.e., good fats), high in fiber and polyphenols are associated with better cognitive function and memory in both humans and animal models. Mechanistically, this could be the direct consequence of dietary components (lipids, vitamins, polyphenols) on the brain, but other mechanisms are also likely to be important. Diet is considered to be the single greatest factor influencing the intestinal microbiome. Diet robustly influences the types and function of micro-organisms (called microbiota) that reside in the gastrointestinal tract. Availability of different types of nutrients (from the diet) will favor or disfavor the abundance and function of certain groups of microbiota. Microbiota are highly metabolically active and produce many metabolites and other factors that can affect the brain including cognition and the development and clinical progression of AD. This review summarizes data to support a model in which microbiota metabolites influence brain function and AD.

Medium-Chain Length Fatty Acids Enhance Aβ Degradation by Affecting Insulin-Degrading Enzyme

The accumulation of amyloid β-protein (Aβ) is one of the major pathological hallmarks of Alzheimer's disease. Insulin-degrading enzyme (IDE), a zinc-metalloprotease, is a key enzyme involved in Aβ degradation, which, in addition to Aβ production, is critical for Aβ homeostasis. Here, we demonstrate that saturated medium-chain fatty acids (MCFAs) increase total Aβ degradation whereas longer saturated fatty acids result in an inhibition of its degradation, an effect which could not be detected in IDE knock-down cells. Further analysis of the underlying molecular mechanism revealed that MCFAs result in an increased exosomal IDE secretion, leading to an elevated extracellular and a decreased intracellular IDE level whereas gene expression of IDE was unaffected in dependence of the chain length. Additionally, MCFAs directly elevated the enzyme activity of recombinant IDE, while longer-chain length fatty acids resulted in an inhibited IDE activity. The effect of MCFAs on IDE activity could be confirmed in mice fed with a MCFA-enriched diet, revealing an increased IDE activity in serum. Our data underline that not only polyunsaturated fatty acids such as docosahexaenoic acid (DHA), but also short-chain fatty acids, highly enriched, for example in coconut oil, might be beneficial in preventing or treating Alzheimer's disease.

Dietary medium chain triglycerides for management of epilepsy: New data from human, dog, and rodent studies

Many studies show that glucose metabolism in epileptic brain areas can be impaired. Energy is crucial to maintain normal brain function, including ion and neurotransmitter balances. Energy deficits can lead to disruption of ion gradients, which can trigger neuronal depolarization and generation of seizures. Thus, perturbed metabolic processing of glucose in epileptogenic brain areas indicates a specific nutritional need for people and animals with epilepsy, as they are likely to benefit from auxiliary brain fuels other than glucose. Ketogenic diets provide the ketone bodies acetoacetate and β-hydroxybutyrate, which can be used as auxiliary fuel by the brain. In approximately 50% children and adults with certain types of epilepsy, who can tolerate and maintain these dietary regimens, seizure frequency can be effectively reduced. More recent data demonstrate that addition of medium chain triglycerides (MCTs), which provide the medium chain fatty acids octanoic and decanoic acid, as well as ketone bodies as auxiliary brain energy, can be beneficial in rodent seizure models, and dogs and humans with epilepsy. Here, this evidence is reviewed, including tolerance in 65% of humans, efficacy studies in dogs, possible anticonvulsant mechanisms of actions of MCTs, and specifically decanoic acid as well as metabolic and antioxidant mechanisms. In conclusion, MCTs are a promising adjunct to standard pharmacological treatment for both humans and dogs with epilepsy, as they lack central nervous system side effects found with current antiepileptic drugs. There is now a need for larger clinical trials in children, adults, and dogs to find the ideal composition and doses of MCTs and the types of epilepsy that respond best.

Pharmacotherapeutics in clinical ethology: treatment efficacy, clinical pathology and outcome

The use of psychopharmaceutical agents is a core aspect of treatment in veterinary behavioural medicine. Psychotropic medication use has shifted the focus of treatment from purely behavioural and environmental interventions to a multi-modal approach. Objective measures of efficacy are required for the licensing of medication. Pharmacotherapeutics have come to encompass supplements and diets, in addition to prescription medications. The first part of this paper examines the efficacy of medications, supplements and diets used in behavioural medicine. Foci include the role of evolution in the types of behavioural concerns reported, the importance of defining abnormal or pathological behaviour, use of terminology that supports stratified mechanistic diagnoses aid in understanding presentation and response clusters, and rational use of medication to relieve emotional, mental and behavioural suffering, given these diagnoses and clusters. The second part of this paper examines the extent to which variation in patient response to medication can enlighten us about mechanisms and outcomes of distress using a series of 3 patient populations who are the focus of studies on separation anxiety and noise reactivity. This response surface approach can be useful for understanding differences in populations in susceptibility to behavioural pathology and in medication response, and may suggest new avenues for drug development and application.

Ketogenic Diet for the Treatment and Prevention of Dementia: A Review

Dementia (major neurocognitive disorder) is an increasingly common syndrome with a significant burden on patients, caregivers, the health-care system, and the society. The prevalence of dementia will certainly continue to grow as the US population ages. Current treatments for dementia, though, are limited. One proposed nonpharmacologic approach for the delay or prevention of dementia is the use of a ketogenic diet. The ketogenic diet was originally employed to treat refractory epilepsy and has shown promise in many neurologic diseases. It has also gained recent popularity for its weight loss effects. Several preclinical studies have confirmed a benefit of ketosis on cognition and systemic inflammation. Given the renewed emphasis on neuroinflammation as a pathogenic contributor to cognitive decline, and the decreased systemic inflammation observed with the ketogenic diet, it is plausible that this diet may delay, ameliorate, or prevent progression of cognitive decline. Several small human studies have shown benefit on cognition in dementia with a ketogenic diet intervention. Future, large controlled studies are needed to confirm this benefit; however, the ketogenic diet has shown promise in regard to delay or mitigation of symptoms of cognitive decline.

Targeted Metabolomics With Ultraperformance Liquid Chromatography-Mass Spectrometry (UPLC-MS) Highlights Metabolic Differences in Healthy and Atopic Staffordshire Bull Terriers Fed Two Different Diets, A Pilot Study

Background: While anecdotal evidence has long claimed that a raw meat-based diet (RMBD) improves the metabolic health of canines, no rigorous scientific study has clarified this issue. Canine atopic dermatitis (CAD) has also been linked to metabolic health, but its relation to diet remains poorly understood. This study investigates whether dietary choice is linked to metabolic health in healthy and CAD-diagnosed canines via targeted serum and urine metabolomic analysis of polar, non-ionic metabolites, as well as whether the underlying CAD condition modulates the response to nutritional intake. Materials and Methods: Serum metabolites of client-owned Staffordshire bull terriers, divided into CAD-diagnosed (n = 14) and healthy (n = 6) cohorts, were studied. Urine metabolites of a subset of the CAD-diagnosed canines (n = 8) were also studied. The canines were split into two cohorts based on diet. The first cohort were fed a commercially available high-fat, moderate-protein, low-carbohydrate RMBD (n = 11, CAD diagnosed n = 8, healthy n = 3). Those in the second cohort were fed a commercially available moderate-fat, moderate-protein, high-carbohydrate kibble diet (KD) (n = 9: CAD diagnosed n = 6, healthy n = 3). The diet intervention period lasted approximately 4.5 months (median 135 days). Statistical analyses of the serum profiles across all dogs (n = 20) and the urine profiles of the CAD-diagnosed subset (n = 8) were performed. Results and Discussion: The KD cohort was found to have higher concentrations of methionine than the RMBD cohort, both in serum (all dogs, p < 0.0001) and in urine (CAD-only cohort, p < 0.0002), as well as cystathionine and 4-pyridoxic acid. Methionine plays important roles in homocysteine metabolism, and elevated levels have been implicated in various pathologies. The CAD (n = 14) cohort dogs showed starker metabolic changes in response to diet regarding these pathways compared to the healthy (n = 6) cohort. However, there was no significant change in CAD severity as a result of either diet. Likely due to the higher meat content of the RMBD, higher concentrations of several carnitines and creatine were found in the RMBD cohort. Citrulline was found in higher concentrations in the KD cohort. Our findings provide insight into the relationship between diet and the serum and urine metabolite profiles of canines. They also suggest that neither diet significantly affected CAD severity.

Efficacy of medium chain triglyceride oil dietary supplementation in reducing seizure frequency in dogs with idiopathic epilepsy without cluster seizures: a non-blinded, prospective clinical trial

BACKGROUND

Despite appropriate antiseizure drug (ASD) treatment, around two-thirds of dogs with idiopathic epilepsy (IE) have seizures long-term and 20-30per cent of affected dogs remain poorly controlled.

METHODS

The current study aim is to test in a field trial the efficacy and tolerability of a commercially available diet enriched with 6.5per cent medium chain triglyceride (MCT) oil in dogs (n=21) with at least a tier 1 idiopathic epilepsy diagnosis, without cluster seizures, in 10 veterinary practices across Europe. Each dog's quality of life (QoL), ataxia, sedation and frequency and severity of seizures were recorded by owners throughout the study.

RESULTS

The mean seizure frequency per month, averaged over the entire 84-day study, significantly (P=0.04) decreased 32per cent compared with the baseline monthly seizure frequency recorded during the month immediately before feeding the diet. Similarly, the seizure days rate (days/month) also declined (P<0.001) by 42per cent. QoL was reported as very good to excellent (>8.5/10) in 20 of the 21 dogs before starting the diet and this remained unchanged during the trial.

CONCLUSIONS

This study demonstrates the use of a diet enriched with MCTs as an adjunct to ASD treatment may have some antiseizure properties for dogs diagnosed with IE, as demonstrated in previous studies.

Ketone Bodies Promote Amyloid-β1-40 Clearance in a Human in Vitro Blood-Brain Barrier Model

Alzheimer’s disease (AD) is characterized by the abnormal accumulation of amyloid-β (Aβ) peptides in the brain. The pathological process has not yet been clarified, although dysfunctional transport of Aβ across the blood–brain barrier (BBB) appears to be integral to disease development. At present, no effective therapeutic treatment against AD exists, and the adoption of a ketogenic diet (KD) or ketone body (KB) supplements have been investigated as potential new therapeutic approaches. Despite experimental evidence supporting the hypothesis that KBs reduce the Aβ load in the AD brain, little information is available about the effect of KBs on BBB and their effect on Aβ transport. Therefore, we used a human in vitro BBB model, brain-like endothelial cells (BLECs), to investigate the effect of KBs on the BBB and on Aβ transport. Our results show that KBs do not modify BBB integrity and do not cause toxicity to BLECs. Furthermore, the presence of KBs in the culture media was combined with higher MCT1 and GLUT1 protein levels in BLECs. In addition, KBs significantly enhanced the protein levels of LRP1, P-gp, and PICALM, described to be involved in Aβ clearance. Finally, the combined use of KBs promotes Aβ efflux across the BBB. Inhibition experiments demonstrated the involvement of LRP1 and P-gp in the efflux. This work provides evidence that KBs promote Aβ clearance from the brain to blood in addition to exciting perspectives for studying the use of KBs in therapeutic approaches.

Genetic Pathways of Aging and Their Relevance in the Dog as a Natural Model of Human Aging

Aging research has experienced a burst of scientific efforts in the last decades as the growing ratio of elderly people has begun to pose an increased burden on the healthcare and pension systems of developed countries. Although many breakthroughs have been reported in understanding the cellular mechanisms of aging, the intrinsic and extrinsic factors that contribute to senescence on higher biological levels are still barely understood. The dog, Canis familiaris, has already served as a valuable model of human physiology and disease. The possible role the dog could play in aging research is still an open question, although utilization of dogs may hold great promises as they naturally develop age-related cognitive decline, with behavioral and histological characteristics very similar to those of humans. In this regard, family dogs may possess unmatched potentials as models for investigations on the complex interactions between environmental, behavioral, and genetic factors that determine the course of aging. In this review, we summarize the known genetic pathways in aging and their relevance in dogs, putting emphasis on the yet barely described nature of certain aging pathways in canines. Reasons for highlighting the dog as a future aging and gerontology model are also discussed, ranging from its unique evolutionary path shared with humans, its social skills, and the fact that family dogs live together with their owners, and are being exposed to the same environmental effects.

Ketogenic Diet in Alzheimer's Disease

At present, the prevalence of Alzheimer's disease, a devastating neurodegenerative disorder, is increasing. Although the mechanism of the underlying pathology is not fully uncovered, in the last years, there has been significant progress in its understanding. This includes: Progressive deposition of amyloid β-peptides in amyloid plaques and hyperphosphorylated tau protein in intracellular as neurofibrillary tangles; neuronal loss; and impaired glucose metabolism. Due to a lack of effective prevention and treatment strategy, emerging evidence suggests that dietary and metabolic interventions could potentially target these issues. The ketogenic diet is a very high-fat, low-carbohydrate diet, which has a fasting-like effect bringing the body into a state of ketosis. The presence of ketone bodies has a neuroprotective impact on aging brain cells. Moreover, their production may enhance mitochondrial function, reduce the expression of inflammatory and apoptotic mediators. Thus, it has gained interest as a potential therapy for neurodegenerative disorders like Alzheimer's disease. This review aims to examine the role of the ketogenic diet in Alzheimer's disease progression and to outline specific aspects of the nutritional profile providing a rationale for the implementation of dietary interventions as a therapeutic strategy for Alzheimer's disease.

Mediterranean and MIND Diets Containing Olive Biophenols Reduces the Prevalence of Alzheimer's Disease

The risk of Alzheimer’s disease (AD) increases with nonmodifiable conditions including age and lack of effective efficacious pharmacotherapy. During the past decades, the non-pharmacotherapy mode of treatment of dietary modification received extensive attention in AD research. In order to reduce the AD pathology and cognitive decline, various dietary patterns have been attempted including caloric restriction (CR), dietary approaches to stop hypertension (DASH), ketogenic diets (KD), Mediterranean diet (MedDi) and Mediterranean-DASH diet Intervention for Neurological Delay (MIND) diet. Higher adherence to the MedDi diet was associated with decreases in cardiovascular and neurological disorders including AD and related cognitive decline. However, another emerging healthy dietary pattern MIND diet has also been associated with slower rates of cognitive decline and significant reduction of AD rate. Olive serves as one of the building block components of MedDi and MIND diets and the exerted potential health beneficial might be suggested due to the presence of its bioactive constituents such as oleic acids and phenolic compounds (biophenols). A few trials using medical food showed an optimal result in presymptomatic or early stages of AD. The review supports the notion that MedDi and MIND diets display potential for maintaining the cognitive function as nonpharmacological agents against AD pathology and proposed preventative mechanism through the presence of olive biophenols and presents the gaps along with the future directions.

Bridging the Gap between Alzheimer's Disease and Alzheimer's-like Diseases in Animals

The average life span steadily grows in humans and in animals kept as pets or left in sanctuaries making the issue of elderly-associated cognitive impairment a hot-spot for scientists. Alzheimer’s disease (AD) is the most prevalent cause of progressive mental deterioration in aging humans, and there is a growing body of evidence that similar disorders (Alzheimer’s-like diseases, ALD) are observed in animals, more than ever found in senescent individuals. This review reveals up to date knowledge in pathogenesis, hallmarks, diagnostic approaches and modalities in AD faced up with ALD related to different animal species. If found at necropsy, there are striking similarities between senile plaques (SP) and neurofibrillary tangles (NFT) in human and animal brains. Also, the set of clinical symptoms in ALD resembles that observed in AD. At molecular and microscopic levels, the human and animal brain histopathology in AD and ALD shows a great resemblance. AD is fatal, and the etiology is still unknown, although the myriad of efforts and techniques were employed in order to decipher the molecular mechanisms of disease onset and its progression. Nowadays, according to an increasing number of cases reported in animals, apparently, biochemistry of AD and ALD has a lot in common. Described observations point to the importance of extensive in vivo models and extensive pre-clinical studies on aging animals as a suitable model for AD disease.

Role of Ketogenic Diets in Neurodegenerative Diseases (Alzheimer's Disease and Parkinson's Disease)

The goal of this review was to assess the effectiveness of ketogenic diets on the therapy of neurodegenerative diseases. The ketogenic diet is a low-carbohydrate and fat-rich diet. Its implementation has a fasting-like effect, which brings the body into a state of ketosis. The ketogenic diet has, for almost 100 years, been used in the therapy of drug-resistant epilepsy, but current studies indicate possible neuroprotective effects. Thus far, only a few studies have evaluated the role of the ketogenic diet in the prevention of Parkinson’s disease (PD) and Alzheimer’s disease (AD). Single studies with human participants have demonstrated a reduction of disease symptoms after application. The application of the ketogenic diet to elderly people, however, raises certain concerns. Persons with neurodegenerative diseases are at risk of malnutrition, while food intake reduction is associated with disease symptoms. In turn, the ketogenic diet leads to a reduced appetite; it is not attractive from an organoleptic point of view, and may be accompanied by side effects of the gastrointestinal system. All this may lead to further lowering of consumed food portions by elderly persons with neurodegenerative diseases and, in consequence, to further reduction in the supply of nutrients provided by the diet. Neither data on the long-term application of the ketogenic diet in patients with neurodegenerative disease or data on its effects on disease symptoms are available. Further research is needed to evaluate the suitability of the ketogenic diet in the therapy of AD- or PD-affected persons.

Ketogenic Diets for Adult Neurological Disorders

The current review highlights the evidence supporting the use of ketogenic diet therapies in the management of a growing number of neurological disorders in adults. An overview of the scientific literature supporting posited mechanisms of therapeutic efficacy is presented including effects on neurotransmission, oxidative stress, and neuro-inflammation. The clinical evidence supporting ketogenic diet use in the management of adult epilepsy, malignant glioma, Alzheimer's disease, migraine headache, motor neuron disease, and other neurologic disorders is highlighted and reviewed. Lastly, common adverse effects of ketogenic therapy in adults, including gastrointestinal symptoms, weight loss, and transient dyslipidemia are discussed.

The Expanding Role of Ketogenic Diets in Adult Neurological Disorders

The current review highlights the evidence supporting the use of ketogenic diet therapies in the management of adult epilepsy, adult malignant glioma and Alzheimer's disease. An overview of the scientific literature, both preclinical and clinical, in each area is presented and management strategies for addressing adverse effects and compliance are discussed.

Alzheimer's Disease as the Product of a Progressive Energy Deficiency Syndrome in the Central Nervous System: The Neuroenergetic Hypothesis

The decreased availability of metabolizable energy resources in the central nervous system is hypothesized to be a key factor in the pathogenesis of Alzheimer's disease. More specifically, the age-related decline in the ability of glucose to cross the blood-brain barrier creates a metabolic stress that shifts the normal, benign processing of amyloid-β protein precursor toward pathways associated with the production of amyloid-β plaques and tau-containing neurofibrillary tangles that are characteristic of the disease. The neuroenergetic hypothesis provides insight into the etiology of Alzheimer's disease and illuminates new approaches for diagnosis, monitoring, and treatment.

Effect of a ketogenic meal on cognitive function in elderly adults: potential for cognitive enhancement

RATIONALE

Glucose is the principal energy substrate for the brain, although ketone bodies are an effective alternative. Evidence suggests that elevation of plasma ketone body levels through oral intake of medium chain triglycerides (MCTs) may improve cognitive function.

OBJECTIVES

We tried to examine the possible effects of a ketogenic meal serving on cognition in elderly non-demented subjects.

METHODS

Subjects were 19 non-demented elderly adults over 60 years old (13 females; mean age: 66.1 ± 2.9 years) who underwent neurocognitive tests 90 and 180 min after oral intake of a ketogenic meal (Ketonformula®) containing 20 g of MCTs and an isocaloric placebo meal without MCTs on separate days.

RESULTS

Elevation of plasma ketone concentration after intake of a single ketogenic meal containing 20 g of MCTs was confirmed (all p < 0.001). As for cognition, improvements were observed in the digit span test, Trail-Making Test B, and the global score (Z = -2.4, p = 0.017) following the ketogenic meal and the change in the executive functioning score was positively correlated with that of the plasma β-hydroxybutyrate level. The cognition-enhancing effect was observed predominantly for individuals who had a relatively low global score at baseline (Z = -2.8, p = 0.005), compared to individuals with a high global score (Z = -0.7, p = 0.51).

CONCLUSIONS

Plasma levels of ketone bodies were successfully increased after intake of the ketogenic meal. The ketogenic meal was suggested to have positive effects on working memory, visual attention, and task switching in non-demented elderly.

The role of dietary coconut for the prevention and treatment of Alzheimer's disease: potential mechanisms of action

Coconut, Cocos nucifera L., is a tree that is cultivated to provide a large number of products, although it is mainly grown for its nutritional and medicinal values. Coconut oil, derived from the coconut fruit, has been recognised historically as containing high levels of saturated fat; however, closer scrutiny suggests that coconut should be regarded more favourably. Unlike most other dietary fats that are high in long-chain fatty acids, coconut oil comprises medium-chain fatty acids (MCFA). MCFA are unique in that they are easily absorbed and metabolised by the liver, and can be converted to ketones. Ketone bodies are an important alternative energy source in the brain, and may be beneficial to people developing or already with memory impairment, as in Alzheimer's disease (AD). Coconut is classified as a highly nutritious 'functional food'. It is rich in dietary fibre, vitamins and minerals; however, notably, evidence is mounting to support the concept that coconut may be beneficial in the treatment of obesity, dyslipidaemia, elevated LDL, insulin resistance and hypertension - these are the risk factors for CVD and type 2 diabetes, and also for AD. In addition, phenolic compounds and hormones (cytokinins) found in coconut may assist in preventing the aggregation of amyloid-β peptide, potentially inhibiting a key step in the pathogenesis of AD. The purpose of the present review was to explore the literature related to coconut, outlining the known mechanistic physiology, and to discuss the potential role of coconut supplementation as a therapeutic option in the prevention and management of AD.

Nutritional or pharmacological activation of HCA(2) ameliorates neuroinflammation

Neuroinflammation is a pathology common to many neurological diseases, including multiple sclerosis (MS) and stroke. However, therapeutic attempts to modulate neuroinflammation have proved difficult. Neuroinflammatory cells express HCA2, a receptor for the endogenous neuroprotective ketone body β-hydroxybutyrate (BHB) as well as for the drugs dimethyl fumarate (DMF) and nicotinic acid, which have established efficacy in the treatment of MS and experimental stroke, respectively. This review summarizes the evidence that HCA2 is involved in the therapeutic effects of DMF, nicotinic acid, and ketone bodies in reducing neuroinflammation. Furthermore, we discuss the mechanisms underlying the beneficial effects of HCA2 activation in neuroinflammatory diseases and the therapeutic potential of recently developed synthetic ligands of HCA2.

Canine and feline obesity: a review of pathophysiology, epidemiology, and clinical management

Canine and feline obesity rates have reached pandemic proportions and are similar to those in humans, with approximately 30%-40% of dogs and cats being overweight to obese. Obesity has been associated with other health problems, including osteoarthritis, renal disease, skin disease, insulin resistance, and neoplasia in dogs, while in cats obesity is associated with dermatological issues, diabetes mellitus, neoplasia, and urolithiasis. The health issues appear to be slightly different across the two species, which may be due to some inherent differences in the hormonal milieu involved in obesity that differs between the dog and the cat. In this review, we discuss the complicated nature of the pathogenesis of obesity, the hormonal stimulus for orexigenic and anorexigenic behavior, adipose tissue as an endocrine organ, and most importantly, clinical management of the number one disease in canine and feline medicine.

Comparison of serum concentrations of symmetric dimethylarginine and creatinine as kidney function biomarkers in healthy geriatric cats fed reduced protein foods enriched with fish oil, L-carnitine, and medium-chain triglycerides

The purpose of this study was to determine whether feeding cats reduced protein and phosphorus foods with added fish oil, L-carnitine, and medium-chain triglycerides (MCT) altered serum biomarkers of renal function. Thirty-two healthy cats, mean age 14.0 (8.3-19.6) years, were fed control food or one of two experimental foods for 6 months. All foods had similar concentrations of moisture, protein, and fat (approximately 8.0%, 26.5%, and 20.0%, respectively). Both experimental foods contained added fish oil (1.5%) and L-carnitine (500 mg/kg). Experimental-food 2 also contained increased MCT (10.5% from coconut oil), 1.5% added corn oil, and reduced animal fat. Glomerular filtration rate (GFR), serum biochemistries, renal function biomarkers including serum creatinine (sCr) and symmetrical dimethylarginine (SDMA), and plasma metabolomic profiles were measured at baseline, and at 1.5, 3, and 6 months. Body composition was determined by dual-energy X-ray absorptiometry. Although both experimental foods altered plasma fatty acids, carnitine and related metabolites, and lysophospholipid concentrations, there were no changes in renal function biomarkers. There was, however, a benefit in using SDMA versus sCr to assess renal function in older cats with less total lean mass. Compared with cats <12 years, those >15 years had lower total lean mass (P < 0.01), lower GFR (P = 0.04), and lower sCr concentrations (P < 0.01). However, SDMA concentrations (P < 0.01) were higher in older cats. This study shows that in cats, serum SDMA concentration is more highly correlated with GFR than sCr concentration, and, unlike sCr, which declines with age because of muscle wasting, SDMA increases as GFR declines with age.

Ketogenic diet in neuromuscular and neurodegenerative diseases

An increasing number of data demonstrate the utility of ketogenic diets in a variety of metabolic diseases as obesity, metabolic syndrome, and diabetes. In regard to neurological disorders, ketogenic diet is recognized as an effective treatment for pharmacoresistant epilepsy but emerging data suggests that ketogenic diet could be also useful in amyotrophic lateral sclerosis, Alzheimer, Parkinson's disease, and some mitochondriopathies. Although these diseases have different pathogenesis and features, there are some common mechanisms that could explain the effects of ketogenic diets. These mechanisms are to provide an efficient source of energy for the treatment of certain types of neurodegenerative diseases characterized by focal brain hypometabolism; to decrease the oxidative damage associated with various kinds of metabolic stress; to increase the mitochondrial biogenesis pathways; and to take advantage of the capacity of ketones to bypass the defect in complex I activity implicated in some neurological diseases. These mechanisms will be discussed in this review.

Nutrition of aging dogs

Aging is a normal process characterized by a variety of physiologic changes. Geriatric dogs are also more likely to be afflicted with certain disease conditions. Both normal and abnormal physiologic changes associated with aging in the dog may be amenable to nutritional intervention. Specific alterations in nutrients or in dietary characteristics can be beneficial; however, these are best done in the context of an individualized nutritional assessment and monitoring paradigm.

A ketogenic diet improves motor performance but does not affect β-amyloid levels in a mouse model of Alzheimer's disease

β-Amyloid (Aβ), a small, fibrillogenic peptide, is known to play an important role in the pathogenesis of Alzheimer's disease (AD) in the brain. In addition, Aβ accumulates in skeletal muscle cells in individuals with sporadic inclusion body myositis (sIBM), an age-related muscle disease. Because of the socioeconomic burden associated with age-related diseases, particularly AD, there has been considerable emphasis on studying potential therapeutic strategies. The high-fat, low carbohydrate ketogenic diet has been used extensively to treat refractory childhood epilepsy and has been studied as a potential treatment for other neurological diseases, including Parkinson's disease and AD. In this study, we fed young APP/PS1 knock-in mice, which have a whole body knock-in of AD-related genes, a ketogenic diet and determined the effect on Aβ levels in the brain and skeletal muscle, as well motor performance and oxidative stress. Aβ and its precursor, the β-C-terminal fragment of amyloid precursor protein (CTFβ), were unchanged overall in both the brain and quadriceps after 1 month on the ketogenic diet, and there was no effect on nitrotyrosine, a product of oxidative stress. The ketogenic diet improved performance on the Rota-rod apparatus (p=0.007), however. These data indicate that the ketogenic diet may have some efficacy in the treatment of both neurologic and muscle diseases though the underlying mechanisms do not involve amelioration of Aβ pathology.

Feeding healthy beagles medium-chain triglycerides, fish oil, and carnitine offsets age-related changes in serum fatty acids and carnitine metabolites

The purpose of this study was to determine if feeding dogs medium-chain triglycerides (MCT), fish oil, and L-carnitine enriched foods offsets age-associated changes in serum fatty acids (FA) and carnitine metabolites. Forty-one healthy Beagles, mean age 9.9 years (range 3.1 to 14.8), were fed control or one of two treatment foods for 6 months. All foods were complete and balanced and met the nutrient requirements for adult dogs, and had similar concentrations of moisture, protein, and fat (approx. 7.4%, 14.0%, and 18.1%, respectively). The treatment diets both contained added L-carnitine (300 mg/kg) and 0.6% (treatment food 1) or 1.5% (treatment food 2) added fish oil. Treatment food 2 also had increased MCT from coconut oil, added corn oil, and reduced animal fat. Composition of serum FA was determined by gas chromatography of FA methyl esters. Metabolomic profiles of serum samples were determined from extracted supernatants that were split and run on GC/MS and LC/MS/MS platforms, for identification and relative quantification of small metabolites. Body composition was determined by dual energy x-ray absorptiometry. Among dog groups, there was no change in total-lean-body weight, or in serum total protein and serum albumin concentrations, based on time or dietary treatment. Serum concentrations of carnitine metabolites were decreased in geriatric (>7 years) vs. mature adult (≤ 7 years) dogs, and supplementation with L-carnitine attenuated the effects of aging. The ratio of PUFA to SFA was significantly greater in mature dogs at baseline (P ≤ 0.05). Serum concentrations of eicosapentaenoic and docosahexaenoic FA increased in a dose-dependent manner. Dogs consuming treatment food 2 also had increased serum concentrations of lauric and myristic FA, and decreased concentrations of SFA, MUFA, and arachidonate (all P ≤ 0.05) and their PUFA to SFA ratio increased. In summary, dietary MCT, fish oil, and L-carnitine counterbalanced the effects of aging on circulating concentrations of these compounds.

The ketogenic diet increases brain glucose and ketone uptake in aged rats: a dual tracer PET and volumetric MRI study

Despite decades of study, it is still unclear whether regional brain glucose uptake is lower in the cognitively healthy elderly. Whether regional brain uptake of ketones (β-hydroxybutyrate and acetoacetate [AcAc]), the main alternative brain fuel to glucose, changes with age is unknown. We used a sequential, dual tracer positron emission tomography (PET) protocol to quantify brain (18)F-fluorodeoxyglucose ((18)F-FDG) and (11)C-AcAc uptake in two studies with healthy, male Sprague-Dawley rats: (i) Aged (21 months; 21M) versus young (4 months; 4M) rats, and (ii) The effect of a 14 day high-fat ketogenic diet (KD) on brain (18)F-FDG and (11)C-AcAc uptake in 24 month old rats (24M). Similar whole brain volumes assessed by magnetic resonance imaging, were observed in aged 21M versus 4M rats, but the lateral ventricles were 30% larger in the 21M rats (p=0.001). Whole brain cerebral metabolic rates of AcAc (CMR(AcAc)) and glucose (CMR(glc)) did not differ between 21M and 4M rats, but were 28% and 44% higher, respectively, in 24M-KD compared to 24M rats. The region-to-whole brain ratio of CMR(glc) was 37-41% lower in the cortex and 40-45% lower in the cerebellum compared to CMR(AcAc) in 4M and 21M rats. We conclude that a quantitative measure of uptake of the brain's two principal exogenous fuels was generally similar in healthy aged and young rats, that the % of distribution across brain regions differed between ketones and glucose, and that brain uptake of both fuels was stimulated by mild, experimental ketonemia.

Proteogenomics of synaptosomal mitochondrial oxidative stress

Oxidative stress is frequently implicated in the pathology of neurodegenerative disease. The chief source of this stress is mitochondrial respiration, via the passage of reducing equivalents through the respiratory chain resulting in a small but potentially pathological production of superoxide. The superoxide that is produced during normal respiration is primarily detoxified within the mitochondria by superoxide dismutase 2 (Sod2), a key protein for maintaining mitochondrial function. Mitochondria are distributed throughout the soma of neurons, as well as along neuronal processes and at the synaptic terminus. This distribution of potentially independent mitochondria throughout the neuron, at distinct subcellular locations, allows for the possibility of regional subcellular deficits in mitochondrial function. There has been increasing interest in the quantification and characterization of messages and proteins at the synapse, because of its importance in neurodegenerative disease, most notably Alzheimer disease. Here, we report the transcriptomic and proteomic changes that occur in synaptosomes from frontal cortices of Sod2 null mice. Constitutively Sod2 null mice were differentially dosed with the synthetic catalytic antioxidant EUK-189, which can extend the life span of these mice, as well as uncovering or preventing neurodegeneration due to endogenous oxidative stress. This approach facilitated insight into the quantification of trafficked messages and proteins to the synaptosome. We used two complementary methods to investigate the nature of the synaptosome under oxidative stress: either whole-genome gene expression microarrays or mass spectrometry-based proteomics using isobaric tagging for relative and absolute quantitation of proteins. We characterized the relative enrichment of gene ontologies at both gene and protein expression levels that occurs from mitochondrial oxidative stress in the synaptosome, which may lead to new avenues of investigation in understanding the regulation of synaptic function in normal and diseased states. As a result of using these approaches, we report for the first time an activation of the mTOR pathway in synaptosomes isolated from Sod2 null mice, confirmed by an upregulation of the phosphorylation of 4E-BP1.

Nutritional care for aging cats and dogs

Veterinarians need to be prepared to provide nutritional advice for healthy pets as well as for pets that are ill. Before instituting a dietary change in any patient, especially an older dog or cat, a nutritional evaluation should be completed. This should include an evaluation of the patient, the current diet, and feeding management. Diets should be appropriate to the unique needs of the individual patient. Many diseases in senior pets are “diet-sensitive” meaning that diet can play a role in managing the effects of the disease. Common examples discussed include cognitive dysfunction of aging, osteoarthritis, and obesity.

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.

Clinical signs and management of anxiety, sleeplessness, and cognitive dysfunction in the senior pet

Physical signs of old age may be obvious, but mental and cognitive changes require more careful observation. Changes in behavior may represent the earliest indications of medical problems, or disorders of the central nervous system, and these may be bidirectional. Cognitive dysfunction syndrome is underdiagnosed and affects a substantial portion of aged companion animals. This article describes potential treatment regimens to address age-related behavioral problems, as well as a framework for investigating differential diagnoses. Early identification of changes in behavior is essential for the adequate treatment and management of medical and behavioral problems, and for monitoring outcomes.

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.

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).

That dog is smarter than you know: advances in understanding canine learning, memory, and cognition

Tests of canine cognition are now receiving much deserved attention. Not only are dogs excellent models for human anxiety-related conditions and those involving brain aging, but how dogs learn and problem solve are interesting stand-alone topics. A number of factors can affect learning at the molecular level including stress or distress, factors that affect olfaction, effects of breed and nutritional factors including that may affect available brain energy. This review provides an overview of how these factors may affect baseline learning and brain aging.

A ketogenic diet delays weight loss and does not impair working memory or motor function in the R6/2 1J mouse model of Huntington's disease

Ketogenic diets are high in fat and low in carbohydrates, and have long been used as an anticonvulsant therapy for drug-intractable and pediatric epilepsy. Additionally, ketogenic diets have been shown to provide neuroprotective effects against acute and chronic brain injury, including beneficial effects in various rodent models of neurodegeneration. Huntington's disease is a progressive neurodegenerative disease characterized by neurological, behavioral and metabolic dysfunction, and ketogenic diets have been shown to increase energy molecules and mitochondrial function. We tested the effects of a ketogenic diet in a transgenic mouse model of Huntington's disease (R6/2 1J), with a focus on life-long behavioral and physiological effects. Matched male and female wild-type and transgenic mice were maintained on a control diet or were switched to a ketogenic diet fed ad libitum starting at six weeks of age. We found no negative effects of the ketogenic diet on any behavioral parameter tested (locomotor activity and coordination, working memory) and no significant change in lifespan. Progressive weight loss is a hallmark feature of Huntington's disease, yet we found that the ketogenic diet-which generally causes weight loss in normal animals-delayed the reduction in body weight of the transgenic mice. These results suggest that metabolic therapies could offer important benefits for Huntington's disease without negative behavioral or physiological consequences.