Palmitoylethanolamide and Its Biobehavioral Correlates in Autism Spectrum Disorder: A Systematic Review of Human and Animal Evidence

Novel drug treatments for pain in advanced cancer and serious illness: a focus on neuropathic pain and chemotherapy-induced peripheral neuropathy

Drugs that are commercially available but have novel mechanisms of action should be explored as analgesics. This review will discuss haloperidol, miragabalin, palmitoylethanolamide (PEA), and clonidine as adjuvant analgesics or analgesics. Haloperidol is a sigma-1 receptor antagonist. Under stress and neuropathic injury, sigma-1 receptors act as a chaperone protein, which downmodulates opioid receptor activities and opens several ion channels. Clinically, there is only low-grade evidence that haloperidol improves pain when combined with morphine, methadone, or tramadol in patients who have cancer, pain from fibrosis, radiation necrosis, or neuropathic pain. Miragabalin is a gabapentinoid approved for the treatment of neuropathic pain in Japan since 2019. In randomized trials, patients with diabetic neuropathy have responded to miragabalin. Its long binding half-life on the calcium channel subunit may provide an advantage over other gabapentinoids. PEA belongs to a group of endogenous bioactive lipids called ALIAmides (autocoid local injury antagonist amides), which have a sense role in modulating numerous biological processes in particular non-neuronal neuroinflammatory responses to neuropathic injury and systemic inflammation. Multiple randomized trials and meta-analyses have demonstrated PEA's effectiveness in reducing pain severity arising from diverse pain phenotypes. Clonidine is an alpha2 adrenoceptor agonist and an imidazoline2 receptor agonist, which is U.S. Federal Drug Administration approved for attention deficit hyperactivity disorder in children, Tourette's syndrome, adjunctive therapy for cancer-related pain, and hypertension. Clonidine activation at alpha2 adrenoceptors causes downstream activation of inhibitory G-proteins (Gi/Go), which inhibits cyclic Adenosine monophosphate (AMP) production and hyperpolarizes neuron membranes, thus reducing allodynia. Intravenous clonidine has been used in terminally ill patients with poorly controlled symptoms, in particular pain and agitation.

Complementary and Alternative Medicine for Autism - A Systematic Review

Complementary and Alternative Medicine (CAM) is a therapeutic option currently used by autistic people with continued interest and uptake. There remains limited evidence regarding the efficacy of CAM use in autism. The aim of this systematic review is to comprehensively review published clinical trials to explore the efficacy of CAM in autism. A systematic literature review of available research published from June 2013 to March 2023 was conducted. Our literature search identified 1826 eligible citations, and duplications removed (n = 694) with 102 articles eligible for title/abstract screening. After full text review, 39 studies were included. The results of this systematic review identified that for autistic people, vitamin and mineral supplements may only be of benefit if there is a deficiency. The results also found that the main interventions used were dietary interventions and nutraceuticals, including targeted supplements, vitamins and minerals, omega 3 s and prebiotics, probiotics and digestive enzymes. The evidence does not support some of the most frequently utilised dietary interventions, such as a Gluten Free Casein Free (GFCF) diet, and the use of targeted nutraceutical supplements may be of benefit, but more conclusive research is still required to direct safe and effective treatment.

Therapeutic potential of CBD in Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is a neurodevelopmental condition characterized by persistent deficits in social communication and interaction, as well as restricted and repetitive patterns of behavior. Despite extensive research, effective pharmacological interventions for ASD remain limited. Cannabidiol (CBD), a non-psychotomimetic compound of the Cannabis sativa plant, has potential therapeutic effects on several neurological and psychiatric disorders. CBD interacts with the endocannabinoid system, a complex cell-signaling system that plays a crucial role in regulating various physiological processes, maintaining homeostasis, participating in social and behavioral processing, and neuronal development and maturation with great relevance to ASD. Furthermore, preliminary findings from clinical trials indicate that CBD may have a modulatory effect on specific ASD symptoms and comorbidities in humans. Interestingly, emerging evidence suggests that CBD may influence the gut microbiota, with implications for the bidirectional communication between the gut and the central nervous system. CBD is a safe drug with low induction of side effects. As it has a multi-target pharmacological profile, it becomes a candidate compound for treating the central symptoms and comorbidities of ASD.

Questioning the role of palmitoylethanolamide in psychosis: a systematic review of clinical and preclinical evidence

Introduction

The endocannabinoid (eCB) system disruption has been suggested to underpin the development of psychosis, fueling the search for novel, better-tolerated antipsychotic agents that target the eCB system. Among these, palmitoylethanolamide (PEA), an N-acylethanolamine (AE) with neuroprotective, anti-inflammatory, and analgesic properties, has drawn attention for its antipsychotic potential.

Methods

This Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020-compliant systematic review aimed at reappraising all clinical and preclinical studies investigating the biobehavioral role of PEA in psychosis.

Results

Overall, 13 studies were eligible for data extraction (11 human, 2 animal). Observational studies investigating PEA tone in psychosis patients converged on the evidence for increased PEA plasma (6 human) and central nervous system (CNS; 1 human) levels, as a potential early compensatory response to illness and its severity, that seems to be lost in the longer-term (CNS; 1 human), opening to the possibility of exogenously supplementing it to sustain control of the disorder. Consistently, PEA oral supplementation reduced negative psychotic and manic symptoms among psychosis patients, with no serious adverse events (3 human). No PEA changes emerged in either preclinical psychosis model (2 animal) studied.

Discussion

Evidence supports PEA signaling as a potential psychosis biomarker, also indicating a therapeutic role of its supplementation in the disorder.

Systematic review registration

https://doi.org/10.17605/OSF.IO/AFMTK.

Roles of the Notch signaling pathway and microglia in autism

The Notch signaling pathway is mainly involved in the regulation of neural stem cell proliferation, survival and differentiation during the development of the central nervous system. As a neurodevelopmental disorder, autism is associated with an abnormal increase in the number of microglia in several brain regions. These findings suggest that the pathogenesis of autism may be related to the Notch signaling pathway and microglia. In this review, we discuss how Notch pathway activity leads to behavioral abnormalities such as learning and memory impairment by influencing neuronal biological activities. An increase in microglial protein synthesis and abnormal autophagy can affect synaptic development and lead to behavioral abnormalities, and all of these changes can lead to autism. Furthermore, the Notch signaling pathway regulates the activation and differentiation of microglia and promotes inflammatory responses, leading to the occurrence of autism. When excessive reactive oxygen species (ROS) secreted by microglia cannot be cleared by autophagy in a timely manner, Notch signaling pathway activity is affected, possibly further increasing susceptibility to autism. This review reveals the mechanism underlying the role of the Notch signaling pathway, microglia and their interaction in the pathogenesis of autism and provides a theoretical reference for targeted clinical therapies for autism.

Cannabis Use in Autism: Reasons for Concern about Risk for Psychosis

Being particularly vulnerable to the pro-psychotic effects of cannabinoid exposure, autism spectrum individuals present with an increased risk of psychosis, which may be passed on to their own children. More specifically, cannabis exposure among autism spectrum individuals seems to exert disruptive epigenetic effects that can be intergenerationally inherited in brain areas which play a critical role in schizophrenia pathophysiology. Additionally, because of such cannabinoid-induced epigenetic effects, autism candidate genes present with bivalent chromatin markings which make them more vulnerable to subsequent disruption, possibly leading to psychosis onset later in life. Thus, findings support a developmental trajectory between autism and psychosis, as per endocannabinoid system modulation. However, such evidence has not received the attention it deserves.

PPARα Signaling: A Candidate Target in Psychiatric Disorder Management

Peroxisome proliferator-activator receptors (PPARs) regulate lipid and glucose metabolism, control inflammatory processes, and modulate several brain functions. Three PPAR isoforms have been identified, PPARα, PPARβ/δ, and PPARγ, which are expressed in different tissues and cell types. Hereinafter, we focus on PPARα involvement in the pathophysiology of neuropsychiatric and neurodegenerative disorders, which is underscored by PPARα localization in neuronal circuits involved in emotion modulation and stress response, and its role in neurodevelopment and neuroinflammation. A multiplicity of downstream pathways modulated by PPARα activation, including glutamatergic neurotransmission, upregulation of brain-derived neurotrophic factor, and neurosteroidogenic effects, encompass mechanisms underlying behavioral regulation. Modulation of dopamine neuronal firing in the ventral tegmental area likely contributes to PPARα effects in depression, anhedonia, and autism spectrum disorder (ASD). Based on robust preclinical evidence and the initial results of clinical studies, future clinical trials should assess the efficacy of PPARα agonists in the treatment of mood and neurodevelopmental disorders, such as depression, schizophrenia, and ASD.

Utilizing Genomically Targeted Molecular Data to Improve Patient-Specific Outcomes in Autism Spectrum Disorder

Molecular biology combined with genomics can be a powerful tool for developing potential intervention strategies for improving outcomes in children with autism spectrum disorders (ASD). Monogenic etiologies rarely cause autism. Instead, ASD is more frequently due to many polygenic contributing factors interacting with each other, combined with the epigenetic effects of diet, lifestyle, and environment. One limitation of genomics has been identifying ways of responding to each identified gene variant to translate the information to something clinically useful. This paper will illustrate how understanding the function of a gene and the effects of a reported variant on a molecular level can be used to develop actionable and targeted potential interventions for a gene variant or combinations of variants. For illustrative purposes, this communication highlights a specific genomic variant, SHANK3. The steps involved in developing molecularly genomically targeted actionable interventions will be demonstrated. Cases will be shared to support the efficacy of this strategy and to show how clinicians utilized these targeted interventions to improve ASD-related symptoms significantly. The presented approach demonstrates the utility of genomics as a part of clinical decision-making.

Is It Time to Test the Antiseizure Potential of Palmitoylethanolamide in Human Studies? A Systematic Review of Preclinical Evidence

Antiseizure medications are the cornerstone pharmacotherapy for epilepsy. They are not devoid of side effects. In search for better-tolerated antiseizure agents, cannabinoid compounds and other N-acylethanolamines not directly binding cannabinoid receptors have drawn significant attention. Among these, palmitoylethanolamide (PEA) has shown neuroprotective, anti-inflammatory, and analgesic properties. All studies examining PEA’s role in epilepsy and acute seizures were systematically reviewed. Preclinical studies indicated a systematically reduced PEA tone accompanied by alterations of endocannabinoid levels. PEA supplementation reduced seizure frequency and severity in animal models of epilepsy and acute seizures, in some cases, similarly to available antiseizure medications but with a better safety profile. The peripheral-brain immune system seemed to be more effectively modulated by subchronic pretreatment with PEA, with positive consequences in terms of better responding to subsequent epileptogenic insults. PEA treatment restored the endocannabinoid level changes that occur in a seizure episode, with potential preventive implications in terms of neural damage. Neurobiological mechanisms for PEA antiseizure effect seemed to include the activation of the endocannabinoid system and the modulation of neuroinflammation and excitotoxicity. Although no human study was identified, there is ground for testing the antiseizure potential of PEA and its safety profile in human studies of epilepsy.

Therapeutic effect of palmitoylethanolamide in cognitive decline: A systematic review and preliminary meta-analysis of preclinical and clinical evidence

Cognitive decline is believed to be associated with neurodegenerative processes involving excitotoxicity, oxidative damage, inflammation, and microvascular and blood-brain barrier dysfunction. Interestingly, research evidence suggests upregulated synthesis of lipid signaling molecules as an endogenous attempt to contrast such neurodegeneration-related pathophysiological mechanisms, restore homeostatic balance, and prevent further damage. Among these naturally occurring molecules, palmitoylethanolamide (PEA) has been independently associated with neuroprotective and anti-inflammatory properties, raising interest into the possibility that its supplementation might represent a novel therapeutic approach in supporting the body-own regulation of many pathophysiological processes potentially contributing to neurocognitive disorders. Here, we systematically reviewed all human and animal studies examining PEA and its biobehavioral correlates in neurocognitive disorders, finding 33 eligible outputs. Studies conducted in animal models of neurodegeneration indicate that PEA improves neurobehavioral functions, including memory and learning, by reducing oxidative stress and pro-inflammatory and astrocyte marker expression as well as rebalancing glutamatergic transmission. PEA was found to promote neurogenesis, especially in the hippocampus, neuronal viability and survival, and microtubule-associated protein 2 and brain-derived neurotrophic factor expression, while inhibiting mast cell infiltration/degranulation and astrocyte activation. It also demonstrated to mitigate β-amyloid-induced astrogliosis, by modulating lipid peroxidation, protein nytrosylation, inducible nitric oxide synthase induction, reactive oxygen species production, caspase3 activation, amyloidogenesis, and tau protein hyperphosphorylation. Such effects were related to PEA ability to indirectly activate cannabinoid receptors and modulate proliferator-activated receptor-α (PPAR-α) activity. Importantly, preclinical evidence suggests that PEA may act as a disease-modifying-drug in the early stage of a neurocognitive disorder, while its protective effect in the frank disorder may be less relevant. Limited human research suggests that PEA supplementation reduces fatigue and cognitive impairment, the latter being also meta-analytically confirmed in 3 eligible studies. PEA improved global executive function, working memory, language deficits, daily living activities, possibly by modulating cortical oscillatory activity and GABAergic transmission. There is currently no established cure for neurocognitive disorders but only treatments to temporarily reduce symptom severity. In the search for compounds able to protect against the pathophysiological mechanisms leading to neurocognitive disorders, PEA may represent a valid therapeutic option to prevent neurodegeneration and support endogenous repair processes against disease progression.