Nutritional Ketosis in Parkinson's Disease - a Review of Remaining Questions and Insights

Skin-interfaced microfluidic biosensors for colorimetric measurements of the concentrations of ketones in sweat

Ketones, such as beta-hydroxybutyrate (BHB), are important metabolites that can be used to monitor for conditions such as diabetic ketoacidosis (DKA) and ketosis. Compared to conventional approaches that rely on samples of urine or blood evaluated using laboratory techniques, processes for monitoring of ketones in sweat using on-body sensors offer significant advantages. Here, we report a class of soft, skin-interfaced microfluidic devices that can quantify the concentrations of BHB in sweat based on simple and low-cost colorimetric schemes. These devices combine microfluidic structures and enzymatic colorimetric BHB assays for selective and accurate analysis. Human trials demonstrate the broad applicability of this technology in practical scenarios, and they also establish quantitative correlations between the concentration of BHB in sweat and in blood. The results represent a convenient means for managing DKA and aspects of personal nutrition/wellness.

The ketogenic diet mitigates opioid-induced hyperalgesia by restoring short-chain fatty acids-producing bacteria in the gut

ABSTRACT

Opioids are commonly prescribed to patients with chronic pain. Chronic opioid usage comes with a slew of serious side effects, including opioid-induced hyperalgesia (OIH). The patients with long-term opioid treatment experience paradoxical increases in nociceptive hypersensitivity, namely, OIH. Currently, treatment options for OIH are extremely lacking. In this study, we show that the ketogenic diet recovers the abnormal pain behavior caused by chronic morphine treatment in male mice, and we further show that the therapeutic effect of the ketogenic diet is mediated through gut microbiome. Our 16S rRNA sequencing demonstrates that chronic morphine treatment causes changes in mouse gut microbiota, specifically a decrease in short-chain fatty acids-producing bacteria, and the sequencing data also show that the ketogenic diet rescues those bacteria in the mouse gut. More importantly, we show that supplementation with short-chain fatty acids (butyrate, propionate, and acetate) can delay the onset of OIH, indicating that short-chain fatty acids play a direct role in the development of OIH. Our findings suggest that gut microbiome could be targeted to treat OIH, and the ketogenic diet can be used as a complementary approach for pain relief in patients with chronic opioid treatment. We only used male mice in this study, and thus, our findings cannot be generalized to both sexes.

Sex-specific effects of ketogenic diet on anxiety-like behavior and neuroimmune response in C57Bl/6J mice

The ketogenic diet (KD) has been shown to reduce anxiety and enhance cognitive functions in neurological diseases. However, the sex-specific effects of KD on anxiety-like behavior in healthy individuals and the underlying molecular mechanisms contributing to these effects, including neuroinflammation, are unelucidated. This study investigated the sex-specific effects of KD on anxiety-like behavior and the neuroimmune response in the prefrontal cortex (PFC) and hippocampus of healthy C57BL/6J male and female mice. Animals were fed either a control diet (CD- 17% fat, 65% carb, 18% protein) or a KD (80% fat, 5% carb, 15% protein) for 4 weeks. KD increased the levels of circulating β-hydroxybutyrate (BHB) both in males and females. However, PFC BHB levels were found to be elevated only in KD males. Moreover, KD did not affect the behavior of females but improved motor abilities and reduced anxiety levels in males. KD suppressed the mRNA expression of the pan microglial markers (Cd68, P2ry12) and induced morphological changes in the male PFC microglia. A sex-specific decrease in IL1β and an increase in IL-10 levels was found in the PFC of KD males. A similar trend was observed in the hippocampus of males where KD reduced the mRNA expression of P2ry12, Il1β, and cFos. Additionally, BHB increased the production of IL-10 whereas it decreased the production of IL1β from human microglia in in-vitro conditions. In summary, these results demonstrate that the anxiolytic and motor function enhancement abilities of KD are male-specific. Reduced pro-inflammatory and improved anti-inflammatory factors in the male PFC and hippocampus may underlie these effects.

Cholecystokinin (CCK): a neuromodulator with therapeutic potential in Alzheimer's and Parkinson's disease

Cholecystokinin (CCK) is a neuropeptide modulating digestion, glucose levels, neurotransmitters and memory. Recent studies suggest that CCK exhibits neuroprotective effects in Alzheimer's disease (AD) and Parkinson's disease (PD). Thus, we review the physiological function and therapeutic potential of CCK. The neuropeptide facilitates hippocampal glutamate release and gates GABAergic basket cell activity, which improves declarative memory acquisition, but inhibits consolidation. Cortical CCK alters recognition memory and enhances audio-visual processing. By stimulating CCK-1 receptors (CCK-1Rs), sulphated CCK-8 elicits dopamine release in the substantia nigra and striatum. In the mesolimbic pathway, CCK release is triggered by dopamine and terminates reward responses via CCK-2Rs. Importantly, activation of hippocampal and nigral CCK-2Rs is neuroprotective by evoking AMPK activation, expression of mitochondrial fusion modulators and autophagy. Other benefits include vagus nerve/CCK-1R-mediated expression of brain-derived neurotrophic factor, intestinal protection and suppression of inflammation. We also discuss caveats and the therapeutic combination of CCK with other peptide hormones.

Feasibility and impact of ketogenic dietary interventions in polycystic kidney disease: KETO-ADPKD-a randomized controlled trial

Ketogenic dietary interventions (KDIs) are beneficial in animal models of autosomal-dominant polycystic kidney disease (ADPKD). KETO-ADPKD, an exploratory, randomized, controlled trial, is intended to provide clinical translation of these findings (NCT04680780). Sixty-six patients were randomized to a KDI arm (ketogenic diet [KD] or water fasting [WF]) or the control group. Both interventions induce significant ketogenesis on the basis of blood and breath acetone measurements. Ninety-five percent (KD) and 85% (WF) report the diet as feasible. KD leads to significant reductions in body fat and liver volume. Additionally, KD is associated with reduced kidney volume (not reaching statistical significance). Interestingly, the KD group exhibits improved kidney function at the end of treatment, while the control and WF groups show a progressive decline, as is typical in ADPKD. Safety-relevant events are largely mild, expected (initial flu-like symptoms associated with KD), and transient. Safety assessment is complemented by nuclear magnetic resonance (NMR) lipid profile analyses.

Screening and Targeting Risk Factors for Prodromal Synucleinopathy: Taking Steps toward a Prescriptive Multi-modal Framework

As the prevalence of Parkinson's disease (PD) grows, so too does the population at-risk of developing PD, those in the so-called prodromal period. This period can span from those experiencing subtle motor deficits yet not meeting full diagnostic criteria or those with physiologic markers of disease alone. Several disease-modifying therapies have failed to show a neuroprotective effect. A common criticism is that neurodegeneration, even in the early motor stages, has advanced too far for neuro-restoration-based interventions to be effective. Therefore, identifying this early population is essential. Once identified, these patients could then potentially benefit from sweeping lifestyle modifications to alter their disease trajectory. Herein, we review the literature on risk factors for, and prodromal symptoms of, PD with an emphasis on ones which may be modifiable in the earliest possible stages. We propose a process for identifying this population and speculate on some strategies which may modulate disease trajectory. Ultimately, this proposal warrants prospective studies.

The Role of Ketogenic Diet in the Treatment of Neuroblastoma

The ketogenic diet (KD) was initially used in 1920 for drug-resistant epileptic patients. From this point onward, ketogenic diets became a pivotal part of nutritional therapy research. To date, KD has shown therapeutic potential in many pathologies such as Alzheimer's disease, Parkinson's disease, autism, brain cancers, and multiple sclerosis. Although KD is now an adjuvant therapy for certain diseases, its effectiveness as an antitumor nutritional therapy is still an ongoing debate, especially in Neuroblastoma. Neuroblastoma is the most common extra-cranial solid tumor in children and is metastatic at initial presentation in more than half of the cases. Although Neuroblastoma can be managed by surgery, chemotherapy, immunotherapy, and radiotherapy, its 5-year survival rate in children remains below 40%. Earlier studies have proposed the ketogenic diet as a possible adjuvant therapy for patients undergoing treatment for Neuroblastoma. In this study, we seek to review the possible roles of KD in the treatment of Neuroblastoma.

The Anti-Inflammatory Effect of Preventive Intervention with Ketogenic Diet Mediated by the Histone Acetylation of mGluR5 Promotor Region in Rat Parkinson’s Disease Model: A Dual-Tracer PET Study

Materials and Methods

The neuroprotective effect of ketosis state prior to the onset of PD (preventive KD, KDp) was compared with that receiving KD after the onset (therapeutic KD, KDt) in the lipopolysaccharide- (LPS-) induced rat PD model. A total of 100 rats were randomly assigned to the following 4 groups: sham, LPS, LPS + KDp, and LPS + KDt groups.

Results

Significant dopamine deficient behaviors (rotational behavior and contralateral forelimb akinesia), upregulation of proinflammatory mediators (TNF-α, IL-1β, and IL-6), loss of dopaminergic neurons, reduction of mGluR5⁺ microglia cells, increase of TSPO⁺ microglia cells, reduction of H3K9 acetylation in the mGluR5 promoter region and mGluR5 mRNA expression, and decline in the phosphorylation levels of Akt/GSK-3β/CREB pathway were observed after the intervention of LPS (P < 0.01). TSPO and DAT PET imaging revealed the increased uptake of ¹⁸F-DPA-714 in substantia nigra and decreased uptake of ¹⁸F-FP-CIT in substantia nigra and striatum in LPS-treated rats (P < 0.001). These impairments were alleviated by the dietary intervention of KD, especially with the strategy of KDp (P < 0.05).

Conclusions

The anti-inflammatory effect of KD on PD was supposed to be related to the modulation of Akt/GSK-3β/CREB signaling pathway mediated by the histone acetylation of mGluR5 promotor region. The KD intervention should be initiated prior to the PD onset in high-risk population to achieve a more favorable outcome.

NADPH and Mitochondrial Quality Control as Targets for a Circadian-Based Fasting and Exercise Therapy for the Treatment of Parkinson's Disease

Dysfunctional mitochondrial quality control (MQC) is implicated in the pathogenesis of Parkinson's disease (PD). The improper selection of mitochondria for mitophagy increases reactive oxygen species (ROS) levels and lowers ATP levels. The downstream effects include oxidative damage, failure to maintain proteostasis and ion gradients, and decreased NAD⁺ and NADPH levels, resulting in insufficient energy metabolism and neurotransmitter synthesis. A ketosis-based metabolic therapy that increases the levels of (R)-3-hydroxybutyrate (BHB) may reverse the dysfunctional MQC by partially replacing glucose as an energy source, by stimulating mitophagy, and by decreasing inflammation. Fasting can potentially raise cytoplasmic NADPH levels by increasing the mitochondrial export and cytoplasmic metabolism of ketone body-derived citrate that increases flux through isocitrate dehydrogenase 1 (IDH1). NADPH is an essential cofactor for nitric oxide synthase, and the nitric oxide synthesized can diffuse into the mitochondrial matrix and react with electron transport chain-synthesized superoxide to form peroxynitrite. Excessive superoxide and peroxynitrite production can cause the opening of the mitochondrial permeability transition pore (mPTP) to depolarize the mitochondria and activate PINK1-dependent mitophagy. Both fasting and exercise increase ketogenesis and increase the cellular NAD⁺/NADH ratio, both of which are beneficial for neuronal metabolism. In addition, both fasting and exercise engage the adaptive cellular stress response signaling pathways that protect neurons against the oxidative and proteotoxic stress implicated in PD. Here, we discuss how intermittent fasting from the evening meal through to the next-day lunch together with morning exercise, when circadian NAD⁺/NADH is most oxidized, circadian NADP⁺/NADPH is most reduced, and circadian mitophagy gene expression is high, may slow the progression of PD.

Update to the Treatment of Parkinson's Disease Based on the Gut-Brain Axis Mechanism

Gastrointestinal (GI) symptoms represented by constipation were significant non-motor symptoms of Parkinson’s disease (PD) and were considered early manifestations and aggravating factors of the disease. This paper reviewed the research progress of the mechanism of the gut-brain axis (GBA) in PD and discussed the roles of α-synuclein, gut microbiota, immune inflammation, neuroendocrine, mitochondrial autophagy, and environmental toxins in the mechanism of the GBA in PD. Treatment of PD based on the GBA theory has also been discussed, including (1) dietary therapy, such as probiotics, vitamin therapy, Mediterranean diet, and low-calorie diet, (2) exercise therapy, (3) drug therapy, including antibiotics; GI peptides; GI motility agents, and (4) fecal flora transplantation can improve the flora. (5) Vagotomy and appendectomy were associated but not recommended.

Parkinson’s Disease Etiology: Insights and Associations with Phosphate Toxicity

The present paper investigated the association of Parkinson’s disease etiology with phosphate toxicity, a pathophysiological condition in which dysregulated phosphate metabolism causes excessive inorganic phosphate sequestration in body tissue that damages organ systems. Excessive phosphate is proposed to reduce Complex I function of the mitochondrial electron transport chain in Parkinson’s disease and is linked to opening of the mitochondrial permeability transition pore, resulting in increased reactive oxygen species, inflammation, DNA damage, mitochondrial membrane depolarization, and ATP depletion causing cell death. Parkinson’s disease is associated with α-synuclein and Lewy body dementia, a secondary tauopathy related to hyperphosphorylation of tau protein, and tauopathy is among several pathophysiological pathways shared between Parkinson’s disease and diabetes. Excessive phosphate is also associated with ectopic calcification, bone mineral disorders, and low levels of serum vitamin D in patients with Parkinson’s disease. Sarcopenia and cancer in Parkinson’s disease patients are also associated with phosphate toxicity. Additionally, Parkinson’s disease benefits are related to low dietary phosphate intake. More studies are needed to investigate the potential mediating role of phosphate toxicity in the etiology of Parkinson’s disease.

Nutrition and Gut–Brain Pathways Impacting the Onset of Parkinson’s Disease

An emerging body of literature suggests that long-term gut inflammation may be a silent driver of Parkinson’s disease (PD) pathogenesis. Importantly, specific nutritive patterns might improve gut health for PD risk reduction. Here, we review the current literature on the nutritive patterns and inflammatory markers as a predictor for early detection of PD. This knowledge might be used to foster the detection of early nutritive patterns and preclinical biomarkers to potentially alter PD development and progression.

Ketogenic therapy for Parkinson's disease: A systematic review and synthesis without meta-analysis of animal and human trials

OBJECTIVE

The aim of the present systematic review was to assess the efficacy of ketogenic therapy in Parkinson's disease (PD), using all available data from randomized controlled trials (RCTs) on humans and animal studies with PD models.

DESIGN

Systematic review of in vivo studies.

METHODS

Studies related to the research question were identified through searches in PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), Scopus, clinicaltrials.gov and the gray literature, from inception until November 2021. Rayyan was employed to screen and identify all studies fulfilling the inclusion criteria. Cochrane's revised Risk of Bias 2.0 and SYRCLE tools evaluated bias in RCTs and animal studies, respectively. An effect direction plot was developed to synthesize the evidence of the RCTs.

RESULTS

Twelve studies were identified and included in the qualitative synthesis (4 RCTs and 8 animal trials). Interventions included ketogenic diets (KDs), supplementation with medium-chain triglyceride (MCT) oil, caprylic acid administration and ketone ester drinks. The animal research used zebrafish and rodents, and PD was toxin-induced. Based on the available RCTs, ketogenic therapy does not improve motor coordination and functioning, cognitive impairment, anthropometrics, blood lipids and glycemic control, exercise performance or voice disorders in patients with PD. The evidence is scattered and heterogenous, with single trials assessing different outcomes; thus, a synthesis of the evidence cannot be conclusive regarding the efficacy of ketogenic therapy. On the other hand, animal studies tend to demonstrate more promising results, with marked improvements in locomotor activity, dopaminergic activity, redox status, and inflammatory markers.

CONCLUSIONS

Although animal studies indicate promising results, research on the effect of ketogenic therapy in PD is still in its infancy, with RCTs conducted on humans being heterogeneous and lacking PD-specific outcomes. More studies are required to recommend or refute the use of ketogenic therapy in PD.

The Therapeutic Role of Ketogenic Diet in Neurological Disorders

The ketogenic diet (KD) is a high-fat, low-carbohydrate and adequate-protein diet that has gained popularity in recent years in the context of neurological diseases (NDs). The complexity of the pathogenesis of these diseases means that effective forms of treatment are still lacking. Conventional therapy is often associated with increasing tolerance and/or drug resistance. Consequently, more effective therapeutic strategies are being sought to increase the effectiveness of available forms of therapy and improve the quality of life of patients. For the moment, it seems that KD can provide therapeutic benefits in patients with neurological problems by effectively controlling the balance between pro- and antioxidant processes and pro-excitatory and inhibitory neurotransmitters, and modulating inflammation or changing the composition of the gut microbiome. In this review we evaluated the potential therapeutic efficacy of KD in epilepsy, depression, migraine, Alzheimer’s disease and Parkinson’s disease. In our opinion, KD should be considered as an adjuvant therapeutic option for some neurological diseases.

Metabolic Features of Brain Function with Relevance to Clinical Features of Alzheimer and Parkinson Diseases

Brain metabolism is comprised in Alzheimer’s disease (AD) and Parkinson’s disease (PD). Since the brain primarily relies on metabolism of glucose, ketone bodies, and amino acids, aspects of these metabolic processes in these disorders—and particularly how these altered metabolic processes are related to oxidative and/or nitrosative stress and the resulting damaged targets—are reviewed in this paper. Greater understanding of the decreased functions in brain metabolism in AD and PD is posited to lead to potentially important therapeutic strategies to address both of these disorders, which cause relatively long-lasting decreased quality of life in patients.