Ketogenic diet exposure during the juvenile period increases social behaviors and forebrain neural activation in adult Engrailed 2 null mice

Autism spectrum disorders and the gastrointestinal tract: insights into mechanisms and clinical relevance

Autism spectrum disorders (ASDs) are recognized as central neurodevelopmental disorders diagnosed by impairments in social interactions, communication and repetitive behaviours. The recognition of ASD as a central nervous system (CNS)-mediated neurobehavioural disorder has led most of the research in ASD to be focused on the CNS. However, gastrointestinal function is also likely to be affected owing to the neural mechanistic nature of ASD and the nervous system in the gastrointestinal tract (enteric nervous system). Thus, it is unsurprising that gastrointestinal disorders, particularly constipation, diarrhoea and abdominal pain, are highly comorbid in individuals with ASD. Gastrointestinal problems have also been repeatedly associated with increased severity of the core symptoms diagnostic of ASD and other centrally mediated comorbid conditions, including psychiatric issues, irritability, rigid-compulsive behaviours and aggression. Despite the high prevalence of gastrointestinal dysfunction in ASD and its associated behavioural comorbidities, the specific links between these two conditions have not been clearly delineated, and current data linking ASD to gastrointestinal dysfunction have not been extensively reviewed. This Review outlines the established and emerging clinical and preclinical evidence that emphasizes the gut as a novel mechanistic and potential therapeutic target for individuals with ASD.

Ketogenic diet and behavior: insights from experimental studies

As a journal page for full details. The ketogenic diet (KD) has been established as a treatment for epilepsy, but more recently it has been explored as an alternative or add-on therapy for many other diseases ranging from weight loss to neurological disorders. Animal models are widely used in studies investigating the therapeutic effects of the KD as well as underlying mechanisms. Especially in the context of neurological, psychiatric, and neurodevelopmental disorders essential endpoints are assessed by behavioral and motor tests. Here we summarized research evaluating the influence of the KD on cognition, depressive and anxiety-related behaviors, and social and nutritional behaviors of laboratory rodents. Each section contains a brief description of commonly used behavioral tests highlighting their limitations. Ninety original research articles, written in English, performed on mice or rats, providing measurement of blood beta-hydroxybutyrate (BHB) levels and behavioral evaluation were selected for the review. The majority of research performed in various disease models shows that the KD positively impacts cognition. Almost an equal number of studies report a reduction or no effect of the KD on depressive-related behaviors. For anxiety-related behaviors, the majority of studies show no effect. Despite the increasing use of the KD in weight loss and its appetite-reducing properties the behavioral evaluation of appetite regulation has not been addressed in preclinical studies. This review provides an overview of the behavioral effects of nutritional ketosis addressed to a broad audience of scientists interested in the KD field but not necessarily specializing in behavioral tests.

A Review of the Nutritional Approach and the Role of Dietary Components in Children with Autism Spectrum Disorders in Light of the Latest Scientific Research

Autism spectrum disorder (ASD) is a neurodevelopmental disorder that affects several areas of mental development. The onset of ASD occurs in the first few years of life, usually before the age of 3 years. Proper nutrition is important to ensure that an individual's nutrient and energy requirements are met, and it can also have a moderating effect on the progression of the disorder. A systematic database search was conducted as a narrative review to determine whether nutrition and specific diets can potentially alter gastrointestinal symptoms and neurobehavioral disorders. Databases such as Science Direct, PubMed, Scopus, Web of Science (WoS), and Google Scholar were searched to find studies published between 2000 and September 2023 on the relationship between ASD, dietary approaches, and the role of dietary components. The review may indicate that despite extensive research into dietary interventions, there is a general lack of conclusive scientific data about the effect of therapeutic diets on ASD; therefore, no definitive recommendation can be made for any specific nutritional therapy as a standard treatment for ASD. An individualized dietary approach and the dietician's role in the therapeutic team are very important elements of every therapy. Parents and caregivers should work with nutrition specialists, such as registered dietitians or healthcare providers, to design meal plans for autistic individuals, especially those who would like to implement an elimination diet.

Ketogenic Diet Affects Sleep Architecture in C57BL/6J Wild Type and Fragile X Mice

Nearly half of children with fragile X syndrome experience sleep problems including trouble falling asleep and frequent nighttime awakenings. The goals here were to assess sleep-wake cycles in mice in response to Fmr1 genotype and a dietary intervention that reduces hyperactivity. Electroencephalography (EEG) results were compared with published rest-activity patterns to determine if actigraphy is a viable surrogate for sleep EEG. Specifically, sleep-wake patterns in adult wild type and Fmr1KO littermate mice were recorded after EEG electrode implantation and the recordings manually scored for vigilance states. The data indicated that Fmr1KO mice exhibited sleep-wake patterns similar to wild type littermates when maintained on a control purified ingredient diet. Treatment with a high-fat, low-carbohydrate ketogenic diet increased the percentage of non-rapid eye movement (NREM) sleep in both wild type and Fmr1KO mice during the dark cycle, which corresponded to decreased activity levels. Treatment with a ketogenic diet flattened diurnal sleep periodicity in both wild type and Fmr1KO mice. Differences in several sleep microstructure outcomes (number and length of sleep and wake bouts) supported the altered sleep states in response to a ketogenic diet and were correlated with altered rest-activity cycles. While actigraphy may be a less expensive, reduced labor surrogate for sleep EEG during the dark cycle, daytime resting in mice did not correlate with EEG sleep states.

Diet in treatment of autism spectrum disorders

Altering the diet to treat disease dates to c. 400 BC when starvation was used to reduce seizures in persons with epilepsy. The current diversity of symptomology and mechanisms underlying autism spectrum disorders (ASDs) and a corresponding lack of disorder-specific effective treatments prompts an evaluation of diet as a therapeutic approach to improve symptoms of ASDs. In this review article, we summarize the main findings of nutritional studies in ASDs, with an emphasis on the most common monogenic cause of autism, Fragile X Syndrome (FXS), and the most studied dietary intervention, the ketogenic diet as well as other dietary interventions. We also discuss the gut microbiota in relation to pre- and probiotic therapies and provide insight into future directions that could aid in understanding the mechanism(s) underlying dietary efficacy.

Under or Absent Reporting of Light Stimuli in Testing of Anxiety-Like Behaviors in Rodents: The Need for Standardization

Behavioral neuroscience tests such as the Light/Dark Test, the Open Field Test, the Elevated Plus Maze Test, and the Three Chamber Social Interaction Test have become both essential and widely used behavioral tests for transgenic and pre-clinical models for drug screening and testing. However, as fast as the field has evolved and the contemporaneous involvement of technology, little assessment of the literature has been done to ensure that these behavioral neuroscience tests that are crucial to pre-clinical testing have well-controlled ethological motivation by the use of lighting (i.e., Lux). In the present review paper, N = 420 manuscripts were examined from 2015 to 2019 as a sample set (i.e., n = ~20–22 publications per year) and it was found that only a meager n = 50 publications (i.e., 11.9% of the publications sampled) met the criteria for proper anxiogenic and anxiolytic Lux reported. These findings illustrate a serious concern that behavioral neuroscience papers are not being vetted properly at the journal review level and are being released into the literature and public domain making it difficult to assess the quality of the science being reported. This creates a real need for standardizing the use of Lux in all publications on behavioral neuroscience techniques within the field to ensure that contributions are meaningful, avoid unnecessary duplication, and ultimately would serve to create a more efficient process within the pre-clinical screening/testing for drugs that serve as anxiolytic compounds that would prove more useful than what prior decades of work have produced. It is suggested that improving the standardization of the use and reporting of Lux in behavioral neuroscience tests and the standardization of peer-review processes overseeing the proper documentation of these methodological approaches in manuscripts could serve to advance pre-clinical testing for effective anxiolytic drugs. This report serves to highlight this concern and proposes strategies to proactively remedy them as the field moves forward for decades to come.

Overall Rebalancing of Gut Microbiota Is Key to Autism Intervention

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder with unclear etiology, and due to the lack of effective treatment, ASD patients bring enormous economic and psychological burden to families and society. In recent years, many studies have found that children with ASD are associated with gastrointestinal diseases, and the composition of intestinal microbiota (GM) is different from that of typical developing children. Thus, many researchers believe that the gut-brain axis may play an important role in the occurrence and development of ASD. Indeed, some clinical trials and animal studies have reported changes in neurological function, behavior, and comorbid symptoms of autistic children after rebalancing the composition of the GM through the use of antibiotics, prebiotics, and probiotics or microbiota transfer therapy (MMT). In view of the emergence of new therapies based on the modulation of GM, characterizing the individual gut bacterial profile evaluating the effectiveness of intervention therapies could help provide a better quality of life for subjects with ASD. This article reviews current studies on interventions to rebalance the GM in children with ASD. The results showed that Lactobacillus plantarum may be an effective strain for the probiotic treatment of ASD. However, the greater effectiveness of MMT treatment suggests that it may be more important to pay attention to the overall balance of the patient's GM. Based on these findings, a more thorough assessment of the GM is expected to contribute to personalized microbial intervention, which can be used as a supplementary treatment for ASD.

Spontaneous seizures in adult Fmr1 knockout mice: FVB.129P2-Pde6b+ Tyr Fmr1/J

The prevalence of seizures in individuals with fragile X syndrome (FXS) is ~25%; however, there are no reports of spontaneous seizures in the Fmr1 knockout mouse model of FXS. Herein, we report that 48% of adult (median age P96), Fmr1 knockout mice from our colony were found expired in their home cages. We observed and recorded adult Fmr1 knockout mice having spontaneous convulsions in their home cages. In addition, we captured by electroencephalography an adult Fmr1 knockout mouse having a spontaneous seizure-during preictal, ictal, and postictal phases-which confirmed the presence of a generalized seizure. We did not observe this phenotype in control conspecifics or in juvenile (age <P35) Fmr1 knockout mice. We hypothesized that chronic, random, noise perturbations during development caused the phenotype. We recorded decibels (dB) in our vivarium. The average was 61 dB, but operating the automatic door to the vivarium caused spikes to 95 dB. We modified the door to eliminate noise spikes, which reduced unexpected deaths to 33% in Fmr1 knockout mice raised from birth in this environment (P = 0.07). As the modifications did not eliminate unexpected deaths, we further hypothesized that building vibrations may also be a contributing factor. After installing anti-vibration pads underneath housing carts, unexpected deaths of Fmr1 knockout mice born and raised in this environment decreased to 29% (P < 0.01 compared to the original environment). We also observed significant sex effects, for example, after interventions to reduce sound and vibration, significantly fewer male, but not female, Fmr1 knockout mice died unexpectedly (P < 0.001). The spontaneous seizure phenotype in our Fmr1 knockout mice could serve as a model of seizures observed in individuals with FXS, potentially offering a new translationally-valid phenotype for FXS research. Finally, these observations, although anomalous, serve as a reminder to consider gene-environment interactions when interpreting data derived from Fmr1 knockout mice.

Rescue of histone hypoacetylation and social deficits by ketogenic diet in a Shank3 mouse model of autism

Human genetic sequencing has implicated epigenetic and synaptic aberrations as the most prominent risk factors for autism. Here we show that autistic patients exhibit the significantly lower histone acetylation and elevated HDAC2 expression in prefrontal cortex (PFC). The diminished histone acetylation is also recaptured in an autism mouse model with the deficiency of the Shank3 gene encoding a synaptic scaffolding protein. Treating young (5-week-old) Shank3-deficient mice with a 4-week ketogenic diet, which can act as an endogenous inhibitor of class I HDACs via the major product β-hydroxybutyrate, elevates the level of histone acetylation in PFC neurons. Behavioral assays indicate that ketogenic diet treatment leads to the prolonged rescue of social preference deficits in Shank3-deficient mice. The HDAC downstream target genes encoding NMDA receptor subunits, GRIN2A and GRIN2B, are significantly reduced in PFC of autistic humans. Ketogenic diet treatment of Shank3-deficient mice elevates the transcription and histone acetylation of Grin2a and Grin2b, and restores the diminished NMDAR synaptic function in PFC neurons. These results suggest that the ketogenic diet provides a promising therapeutic strategy for social deficits in autism via the restoration of histone acetylation and gene expression in the brain.

Treating autism spectrum disorder by intervening with gut microbiota

Autism spectrum disorder (ASD) comprises a group of neurodevelopmental disorders with a high prevalence in childhood. The gut microbiota can affect human cognition and moods and has a strong correlation with ASD. Microbiota transplantation, including faecal microbiota transplantation (FMT), probiotics, breastfeeding, formula feeding, gluten-free and casein-free (GFCF) diet and ketogenic diet therapy, may provide satisfying effects for ASD and its related various symptoms. For instance, FMT can improve the core symptoms of ASD and gastrointestinal symptoms. Probiotics, breastfeeding and formula feeding, and GFCF diet can improve gastrointestinal symptoms. The core symptom score still needs to be confirmed by large-scale clinical randomized controlled studies. It is recommended to use a ketogenic diet to treat patients with epilepsy in ASD. At present, the unresolved problems include which of gut the microbiota are beneficial, which of the microorganisms are harmful, how to safely and effectively implant beneficial bacteria into the human body, and how to extract and eliminate harmful microorganisms before transplantation. In future studies, large sample and randomized controlled clinical studies are needed to confirm the mechanism of intestinal microorganisms in the treatment of ASD and the method of microbial transplantation.

Astrocyte Bioenergetics and Major Psychiatric Disorders

Ongoing research continues to add new elements to the emerging picture of involvement of astrocyte energy metabolism in the pathophysiology of major psychiatric disorders, including schizophrenia, mood disorders, and addictions. This review outlines what is known about the energy metabolism in astrocytes, the most numerous cell type in the brain, and summarizes the recent work on how specific perturbations of astrocyte bioenergetics may contribute to the neuropsychiatric conditions. The role of astrocyte energy metabolism in mental health and disease is reviewed on the organism, organ, and cell level. Data arising from genomic, metabolomic, in vitro, and neurobehavioral studies is critically analyzed to suggest future directions in research and possible metabolism-focused therapeutic interventions.

Emerging Role of the Ketogenic Dietary Therapies beyond Epilepsy in Child Neurology

Ketogenic dietary therapies (KDTs) have been in use for refractory paediatric epilepsy for a century now. Over time, KDTs themselves have undergone various modifications to improve tolerability and clinical feasibility, including the Modified Atkins diet (MAD), medium chain triglyceride (MCT) diet and the low glycaemic index treatment (LGIT). Animal and observational studies indicate numerous benefits of KDTs in paediatric neurological conditions apart from their evident benefits in childhood intractable epilepsy, including neurodevelopmental disorders such as autism spectrum disorder, rarer neurogenetic conditions such as Rett syndrome, Fragile X syndrome and Kabuki syndrome, neurodegenerative conditions such as Pelizaeus-Merzbacher disease, and other conditions such as stroke and migraine. A large proportion of the evidence is derived from individual case reports, case series and some small clinical trials, emphasising the vast scope for research in this avenue. The term 'neuroketotherapeutics' has been coined recently to encompass the rapid strides in this field. In the 100^th year of its use for paediatric epilepsy, this review covers the role of the KDTs in non-epilepsy neurological conditions among children.

The influence of estrogen receptor α signaling independent of the estrogen response element on avoidance behavior, social interactions, and palatable ingestive behavior in female mice

Women are vulnerable to developing mental disorders that are associated with circulating estrogens. Estrogens, especially 17β-estradiol (E2), have a wide array of effects on the brain, affecting many behavioral endpoints associated with mental illness. By using a total estrogen receptor (ER) α knockout (KO), an ERα knock in/knock out (KIKO) that lacks a functional DNA-binding domain, and wild type (WT) controls treated with either oil or E2, we evaluated ERα signaling, dependent and independent of the estrogen response element (ERE), on avoidance behavior, social interactions and memory, and palatable ingestive behavior using the open field test, the elevated plus maze, the light dark box, the 3-chamber test, and palatable feeding. We found that ERα does not mediate control of anxiety-like behaviors but rather yielded differences in locomotor activity. In evaluating social preference and social recognition memory, we observed that E2 may modulate these measures in KIKO females but not KO females, suggesting that ERE-independent signaling is likely involved in sociability. Lastly, observations of palatable (high-fat) food intake suggested an increase in palatable eating behavior in oil-treated KIKO females. Oil-treated KO females had a longer latency to food intake, indicative of an anhedonic phenotype compared to oil-treated WT and KIKO females. We have observed that social-related behaviors are potentially influenced by ERE-independent ERα signaling and hedonic food intake requires signaling of ERα.

A Ketogenic Diet and the Treatment of Autism Spectrum Disorder

Autism spectrum disorder (ASD) is characterized by stereotyped behavior and deficits in communication and social interaction. There are no curative treatments for children with ASD. The ketogenic diet (KD) is a high-fat, appropriate-protein, and low-carbohydrate diet that mimics the fasting state of the body and is proven beneficial in drug-resistant epilepsy and some other brain diseases. An increasing number of studies demonstrated that a KD improved autistic behavior, but the underlying mechanisms are not known. We reviewed the neuroprotective role of a KD in ASD, which is likely mediated via improvements in energy metabolism, reductions in antioxidative stress levels, control of neurotransmitters, inhibition of the mammalian target of rapamycin (mTOR) signaling pathway, and modulation of the gut microbiota. A KD is likely a safe and effective treatment for ASD.

Ketogenic therapy in neurodegenerative and psychiatric disorders: From mice to men

Ketogenic diet is a low carbohydrate and high fat diet that has been used for over 100 years in the management of childhood refractory epilepsy. More recently, ketogenic diet has been investigated for a number of metabolic, neurodegenerative and neurodevelopmental disorders. In this comprehensive review, we critically examine the potential therapeutic benefits of ketogenic diet and ketogenic agents on neurodegenerative and psychiatric disorders in humans and translationally valid animal models. The preclinical literature provides strong support for the efficacy of ketogenic diet in a variety of diverse animal models of neuropsychiatric disorders. However, the evidence from clinical studies, while encouraging, particularly in Alzheimer's disease, psychotic and autism spectrum disorders, is limited to case studies and small pilot trials. Firm conclusion on the efficacy of ketogenic diet in psychiatric disorders cannot be drawn due to the lack of randomised, controlled clinical trials. The potential mechanisms of action of ketogenic therapy in these disorders with diverse pathophysiology may include energy metabolism, oxidative stress and immune/inflammatory processes. In conclusion, while ketogenic diet and ketogenic substances hold promise pre-clinically in a variety of neurodegenerative and psychiatric disorders, further studies, particularly randomised controlled clinical trials, are warranted to better understand their clinical efficacy and potential side effects.

Raspberry Ketone [4-(4-Hydroxyphenyl)-2-Butanone] Differentially Effects Meal Patterns and Cardiovascular Parameters in Mice

Raspberry ketone (RK; [4-(4-hydroxyphenyl)-2-butanone]) is a popular nutraceutical used for weight management and appetite control. We sought to determine the physiological benefits of RK on the meal patterns and cardiovascular changes associated with an obesogenic diet. In addition, we explored whether the physiological benefits of RK promoted anxiety-related behaviors. Male and female C57BL/6J mice were administered a daily oral gavage of RK 200 mg/kg, RK 400 mg/kg, or vehicle for 14 days. Commencing with dosing, mice were placed on a high-fat diet (45% fat) or low-fat diet (10% fat). Our results indicated that RK 200 mg/kg had a differential influence on meal patterns in males and females. In contrast, RK 400 mg/kg reduced body weight gain, open-field total distance travelled, hemodynamic measures (i.e., reduced systolic blood pressure (BP), diastolic BP and mean BP), and increased nocturnal satiety ratios in males and females. In addition, RK 400 mg/kg increased neural activation in the nucleus of the solitary tract, compared with vehicle. RK actions were not influenced by diet, nor resulted in an anxiety-like phenotype. Our findings suggest that RK has dose-differential feeding and cardiovascular actions, which needs consideration as it is used as a nutraceutical for weight control for obesity.

Aberrant Mitochondrial Morphology and Function in the BTBR Mouse Model of Autism Is Improved by Two Weeks of Ketogenic Diet

Autism spectrum disorder (ASD) is a highly prevalent neurodevelopmental disorder that exhibits a common set of behavioral and cognitive impairments. Although the etiology of ASD remains unclear, mitochondrial dysfunction has recently emerged as a possible causative factor underlying ASD. The ketogenic diet (KD) is a high-fat, low-carbohydrate diet that augments mitochondrial function, and has been shown to reduce autistic behaviors in both humans and in rodent models of ASD. The aim of the current study was to examine mitochondrial bioenergetics in the BTBR mouse model of ASD and to determine whether the KD improves mitochondrial function. We also investigated changes in mitochondrial morphology, which can directly influence mitochondrial function. We found that BTBR mice had altered mitochondrial function and exhibited smaller more fragmented mitochondria compared to C57BL/6J controls, and that supplementation with the KD improved both mitochondrial function and morphology. We also identified activating phosphorylation of two fission proteins, pDRP1^S616 and pMFF^S146, in BTBR mice, consistent with the increased mitochondrial fragmentation that we observed. Intriguingly, we found that the KD decreased pDRP1^S616 levels in BTBR mice, likely contributing to the restoration of mitochondrial morphology. Overall, these data suggest that impaired mitochondrial bioenergetics and mitochondrial fragmentation may contribute to the etiology of ASD and that these alterations can be reversed with KD treatment.

Autism Spectrum Disorder as a Brain-Gut-Microbiome Axis Disorder

While there are numerous medical comorbidities associated with ASD, gastrointestinal (GI) issues have a significant impact on quality of life for these individuals. Recent findings continue to support the relationship between the gut microbiome and both GI symptoms and behavior, but the heterogeneity within the autism spectrum requires in-depth clinical characterization of these clinical cohorts. Large, diverse, well-controlled studies in this area of research are still needed. Although there is still much to discover about the brain-gut-microbiome axis in ASD, microbially mediated therapies, specifically probiotics and fecal microbiota transplantation have shown promise in the treatment of GI symptoms in ASD, with potential benefit to the core behavioral symptoms of ASD as well. Future research and clinical trials must increasingly consider complex phenotypes in ASD in stratification of large datasets as well as in design of inclusion criteria for individual therapeutic interventions.

Preclinical testing of the ketogenic diet in fragile X mice

The ketogenic diet is highly effective at attenuating seizures in refractory epilepsy, and accumulating evidence in the literature suggests that it may be beneficial in autism. To our knowledge, no one has studied the ketogenic diet in any fragile X syndrome (FXS) model. FXS is the leading known genetic cause of autism. Herein, we tested the effects of chronic ketogenic diet treatment on seizures, body weight, ketone and glucose levels, diurnal activity levels, learning and memory, and anxiety behaviors in Fmr1^KO and littermate control mice as a function of age. The ketogenic diet selectively attenuates seizures in male but not female Fmr1^KO mice and differentially affects weight gain and diurnal activity levels dependent on Fmr1 genotype, sex and age.

Protocol for the Use of the Ketogenic Diet in Preclinical and Clinical Practice

Many age-related diseases are associated with metabolic abnormalities, and dietary interventions may have some benefit in alleviating symptoms or in delaying disease onset. Here, we review the commonly used best practices involved in applications of the ketogenic diet to facilitate its translation into clinical use. The findings reveal that better education of physicians is essential for applying the optimum diet and monitoring its effects in clinical practice. In addition, investigators should carefully consider potential confounding factors prior to commencing studies involving a ketogenic diet. Most importantly, current studies should improve their reporting on ketone levels as well as on the intake of both macro- and micronutrients. Finally, more detailed studies on the mechanism of action are necessary to help identify potential biomarkers for response prediction and monitoring, and to uncover new drug targets to aid the development of novel treatments.

The effect of ketogenic diet on behaviors and synaptic functions of naive mice

INTRODUCTION

Beyond its application as an epilepsy therapy, the ketogenic diet (KD) has been considered a potential treatment for a variety of other neurological and metabolic disorders. However, whether KD promotes functional restoration by reducing the pathological processes underlying individual diseases or through some independent mechanisms is not clear.

METHODS

In this study, we evaluated the effect of KD on a series of behaviors and synaptic functions of young adult naive mice. Wild-type C57BL/6J mice at age of 2-3 months were fed with control diet or KD for three months. Body weight and caloric intake were monitored throughout the experiments. We assessed behavioral performance with seizure induction, motor coordination and activity, anxiety level, spatial learning and memory, sociability, and depression. Synaptic transmission and long-term potentiation were also recorded.

RESULTS

KD-fed mice performed equivalent to control-diet-fed mice in the behavioral tests and electrophysiological assays except exhibiting slower weight gain and increased seizure threshold.

CONCLUSIONS

Our results contribute to the better understanding of effects of the KD on physiological behaviors and synaptic functions.

The Therapeutic Potential of Ketogenic Diet Throughout Life: Focus on Metabolic, Neurodevelopmental and Neurodegenerative Disorders

This chapter reviews the efficacy of the ketogenic diet in a variety of neurodegenerative, neurodevelopmental and metabolic conditions throughout different stages of life. It describes conditions affecting children, metabolic disorders in adults and disorderrs affecting the elderly. We have focused on application of the ketogenic diet in clinical studies and in preclinical models and discuss the benefits and negative aspects of the diet. Finally, we highlight the need for further research in this area with a view of discovering novel mechanistic targets of the ketogenic diet, as a means of maximising the potential benefits/risks ratio.

Therapeutic use of carbohydrate-restricted diets in an autistic child; a case report of clinical and 18FDG PET findings

The ketogenic diet (KD) is a high-fat, adequate-protein, and low-carbohydrate diet that has been used successfully in the treatment of refractory epilepsies for almost 100 years. There has been accumulating evidence to show that the KD may provide a therapeutic benefit in autism spectrum disorders, albeit by a yet-unknown mechanism. We report a case of a 6-year-old patient with high-functioning autism and subclinical epileptic discharges who responded poorly to several behavioural and psychopharmacological treatments. The patient was subsequently placed on the KD due to significant glucose hypometabolism in the brain as revealed by an 18FDG PET. As soon as one month after starting the KD, the patient's behavior and intellect improved (in regard to hyperactivity, attention span, abnormal reactions to visual and auditory stimuli, usage of objects, adaptability to changes, communication skills, fear, anxiety, and emotional reactions); these improvements continued until the end of the observation period at 16 months on the KD. The 18FDG PET, measured at 12 months on the KD, revealed that 18F-FDG uptake decreased markedly and diffusely in the whole cerebral cortex with a relatively low reduction in basal ganglia in comparison to the pre-KD assessment. It warrants further investigation if the 18FDG PET imaging could serve as a biomarker in identifying individuals with autism who might benefit from the KD due to underlying abnormalities related to glucose hypometabolism.

Altered salt taste response and increased tongue epithelium Scnna1 expression in adult Engrailed-2 null mice

Sensory impairments are critical for diagnosing and characterizing neurodevelopmental disorders. Taste is a sensory modality often not well characterized. Engrailed-2 (En2) is a transcription factor critical for neural development, and mice lacking En2 (En2^-/-) display signs of impaired social interaction, cognitive processes (e.g., learning and memory, conditioned fear), and neurodevelopmental alterations. As such, En2^-/- mice display the behavioral deficits and neural impairments characteristic of the core symptoms associated with autism spectrum disorder (ASD). The objective of this study was to characterize the taste function in En2^-/- compared with En2^+/+ in adult male mice. Measuring taste responsiveness by an automated gustometer, En2 null mice had decreased lick responses for 1.6 M fructose, whereas they demonstrated an increased taste responsivity (i.e., relative to water) at 0.3 M sodium chloride and 1 M monosodium glutamate. In a separate cohort of mice, En2^-/- mice had an increased preference for sodium chloride over a range of concentrations (0.032-0.3 M) compared with En2^+/+ mice. Regional gene expression of the tongue epithelium demonstrated an increase in Scnn1a, T2R140, T1R3, and Trpm5 and a decrease in Pkd1l3 in En2 null mice. Taken together, such data indicate that deficits in En2 can produce sensory impairments that can have a measurable impact on taste, particularly salt taste.

Are therapeutic diets an emerging additional choice in autism spectrum disorder management?

BACKGROUND

A nutritional background has been recognized in the pathophysiology of autism and a series of nutritional interventions have been considered as complementary therapeutic options. As available treatments and interventions are not effective in all individuals, new therapies could broaden management options for these patients. Our aim is to provide current literature data about the effect of therapeutic diets on autism spectrum disorder.

DATA SOURCE

A systematic review was conducted by two reviewers independently. Prospective clinical and preclinical studies were considered.

RESULT

Therapeutic diets that have been used in children with autism include ketogenic and gluten/casein-free diet. We were able to identify 8 studies conducted in animal models of autism demonstrating a beneficial effect on neurophysiological and clinical parameters. Only 1 clinical study was found showing improvement in childhood autism rating scale after implementation of ketogenic diet. With regard to gluten/casein-free diet, 4 clinical studies were totally found with 2 of them showing a favorable outcome in children with autism. Furthermore, a combination of gluten-free and modified ketogenic diet in a study had a positive effect on social affect scores. No serious adverse events have been reported.

CONCLUSION

Despite encouraging laboratory data, there is controversy about the real clinical effect of therapeutic diets in patients with autism. More research is needed to provide sounder scientific evidence.

Ketone-Based Metabolic Therapy: Is Increased NAD+ a Primary Mechanism?

The ketogenic diet’s (KD) anticonvulsant effects have been well-documented for nearly a century, including in randomized controlled trials. Some patients become seizure-free and some remain so after diet cessation. Many recent studies have explored its expanded therapeutic potential in diverse neurological disorders, yet no mechanism(s) of action have been established. The diet’s high fat, low carbohydrate composition reduces glucose utilization and promotes the production of ketone bodies. Ketone bodies are a more efficient energy source than glucose and improve mitochondrial function and biogenesis. Cellular energy production depends on the metabolic coenzyme nicotinamide adenine dinucleotide (NAD), a marker for mitochondrial and cellular health. Furthermore, NAD activates downstream signaling pathways (such as the sirtuin enzymes) associated with major benefits such as longevity and reduced inflammation; thus, increasing NAD is a coveted therapeutic endpoint. Based on differential NAD⁺ utilization during glucose- vs. ketone body-based acetyl-CoA generation for entry into the tricarboxylic cycle, we propose that a KD will increase the NAD⁺/NADH ratio. When rats were fed ad libitum KD, significant increases in hippocampal NAD⁺/NADH ratio and blood ketone bodies were detected already at 2 days and remained elevated at 3 weeks, indicating an early and persistent metabolic shift. Based on diverse published literature and these initial data we suggest that increased NAD during ketolytic metabolism may be a primary mechanism behind the beneficial effects of this metabolic therapy in a variety of brain disorders and in promoting health and longevity.

Current nutritional approaches in managing autism spectrum disorder: A review

The link between nutrition and autism spectrum disorder (ASD), which is a complex developmental disorder manifesting itself in significant delays or deviation in interaction and communication, has provided a fresh point of view and signals that nutrition may have a role in the aetiology of ASD, as well as play an active role in treatment by alleviating symptoms.

OBJECTIVE

In this review study aimed at evaluating, with scientific and concrete proof, the current medical nutrition implementations on ASD, existing medical nutrition therapies have been addressed and their effects on ASD symptoms have been discussed in light of current research.

METHODS

We reviewed articles regarding the medical nutritional therapy of autism on current nutritional approaches selected from PubMed, Science Direct, EBSCO, and databases about autism and nutrition.

RESULTS

The research put forward that in individuals with ASD, while gluten-free/casein-free and ketogenic diets, camel milk, curcumin, probiotics, and fermentable foods can play a role in alleviating ASD symptoms, consumption of sugar, additives, pesticides, genetically modified organisms, inorganic processed foods, and hard-to-digest starches may aggravate symptoms.

DISCUSSION

Further prospective controlled trials with large sample sizes are needed before recommendations can be made regarding the ideal ASD diet. This review emphasizes the value of identifying current nutritional approaches specific to individuals with ASD and integrating their effects on symptoms to the conversation and presents suggestions for future research designed to identify medical nutrition therapies targeting this population to better understand the link between ASD and nutrition.

The ketogenic diet affects the social behavior of young male rats

The positive effects of the ketogenic diet (KD) on social behavior have been recently reported in patients and rodent models of autism spectrum disorder (ASD). Given the beneficial effects of the KD on epilepsy, mitochondrial function, carbohydrate metabolism, and inflammation, treatment based on the KD has the potential to reduce some of the ASD-associated symptoms, including abnormal social interactions. It is not known whether the KD influences sociability by reducing the pathological processes underlying ASD or through some independent mechanism. The aim of the present study was to evaluate the influence of the KD on the social behavior of rats. Four-week-old Long-Evans males were treated with the KD for 4 subsequent weeks. Afterwards, behavioral tests were performed in order to evaluate sociability, locomotor activity, working memory, and anxiety-related behaviors. Additionally we performed the social interaction test in animals that were receiving β-hydroxybutyrate or acetone. We have observed that rats fed with the KD showed increased social exploration in three different experimental settings. We did not observe any changes in the level of social interactions in animals treated with exogenous ketone bodies. The results did not show any difference in mobility or anxiety-related behaviors or working memory between the animals fed with the KD or standard rodent chow. In conclusion, we showed that the KD affects the social behavior of wild-type young adult male rats, which was not associated with other behavioral changes.

Ketogenic diet improves behaviors in a maternal immune activation model of autism spectrum disorder

Prenatal factors influence autism spectrum disorder (ASD) incidence in children and can increase ASD symptoms in offspring of animal models. These may include maternal immune activation (MIA) due to viral or bacterial infection during the first trimesters. Unfortunately, regardless of ASD etiology, existing drugs are poorly effective against core symptoms. For nearly a century a ketogenic diet (KD) has been used to treat seizures, and recent insights into mechanisms of ASD and a growing recognition that immune/inflammatory conditions exacerbate ASD risk has increased interest in KD as a treatment for ASD. Here we studied the effects of KD on core ASD symptoms in offspring exposed to MIA. To produce MIA, pregnant C57Bl/6 mice were injected with the viral mimic polyinosinic-polycytidylic acid; after weaning offspring were fed KD or control diet for three weeks. Consistent with an ASD phenotype of a higher incidence in males, control diet-fed MIA male offspring were not social and exhibited high levels of repetitive self-directed behaviors; female offspring were unaffected. However, KD feeding partially or completely reversed all MIA-induced behavioral abnormalities in males; it had no effect on behavior in females. KD-induced metabolic changes of reduced blood glucose and elevated blood ketones were quantified in offspring of both sexes. Prior work from our laboratory and others demonstrate KDs improve relevant behaviors in several ASD models, and here we demonstrate clear benefits of KD in the MIA model of ASD. Together these studies suggest a broad utility for metabolic therapy in improving core ASD symptoms, and support further research to develop and apply ketogenic and/or metabolic strategies in patients with ASD.

Ketogenic diets improve behaviors associated with autism spectrum disorder in a sex-specific manner in the EL mouse

The core symptoms of autism spectrum disorder are poorly treated with current medications. Symptoms of autism spectrum disorder are frequently comorbid with a diagnosis of epilepsy and vice versa. Medically-supervised ketogenic diets are remarkably effective nonpharmacological treatments for epilepsy, even in drug-refractory cases. There is accumulating evidence that supports the efficacy of ketogenic diets in treating the core symptoms of autism spectrum disorders in animal models as well as limited reports of benefits in patients. This study tests the behavioral effects of ketogenic diet feeding in the EL mouse, a model with behavioral characteristics of autism spectrum disorder and comorbid epilepsy. Male and female EL mice were fed control diet or one of two ketogenic diet formulas ad libitum starting at 5 weeks of age. Beginning at 8 weeks of age, diet protocols continued and performance of each group on tests of sociability and repetitive behavior was assessed. A ketogenic diet improved behavioral characteristics of autism spectrum disorder in a sex- and test-specific manner; ketogenic diet never worsened relevant behaviors. Ketogenic diet feeding improved multiple measures of sociability and reduced repetitive behavior in female mice, with limited effects in males. Additional experiments in female mice showed that a less strict, more clinically-relevant diet formula was equally effective in improving sociability and reducing repetitive behavior. Taken together these results add to the growing number of studies suggesting that ketogenic and related diets may provide significant relief from the core symptoms of autism spectrum disorder, and suggest that in some cases there may be increased efficacy in females.