Kayla M. Teopiz

Parkinson’s disease (PD) is a severe neurodegenerative disorder characterized by prominent motor and non-motor (e.g., cognitive) abnormalities. Notwithstanding Food and Drug Administration (FDA)-approved treatments (e.g., L-dopa), most persons with PD do not adequately benefit from the FDA-approved treatments and treatment emergent adverse events are often reasons for discontinuation. To date, no current therapy for PD is disease modifying or curative. Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are central nervous system (CNS) penetrant and have shown to be neuroprotective against oxidative stress, neuroinflammation, and insulin resistance, as well as promoting neuroplasticity. Preclinical evidence suggests that GLP-1RAs also attenuate the accumulation of α-synuclein. The cellular and molecular effects of GLP-1RAs provide a basis to hypothesize putative therapeutic benefit in individuals with PD. Extant preclinical and clinical trial evidence in PD provide preliminary evidence of clinically meaningful benefit in the cardinal features of PD. Herein, we synthesize extant preclinical and early-phase clinical evidence, suggesting that GLP-1RAs may be beneficial as a treatment and/or illness progression modification therapeutic in PD.

Suicide accounts for over 700,000 deaths per year globally and remains a public health priority. Evidence suggests that sleep-related interventions may be effective in reducing depressive symptom severity and suicidal thoughts in patients diagnosed with depression and comorbid insomnia. This study aims to systematically review the efficacy of sedative-hypnotics and/or cognitive behavioral therapy for insomnia (CBT-I) on measures of suicidality. In accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, PubMed, Medline, Cochrane Library, Embase, Scopus, and Web of Science were searched from inception to July 30, 2024. Studies were included if they (1) were randomized controlled trials (RCTs) and (2) reported on suicide-related measures associated with sleep interventions as a primary outcome, secondary outcome, or a safety measure. We endeavored to define and operationalize suicidality as suicidal ideation (SI), suicide attempts (SA), and suicide completion (SC). In cases where study authors failed to separate these three dimensions, the term “suicidality” was applied. Eighteen studies were identified meeting inclusion criteria, comprised of studies investigating benzodiazepines (n = 2), Z-drugs (n=4), orexin receptor antagonists (ORAs) (n=8), and CBT-I (n=4). Zolpidem reduces SI as well as insomnia (linear association = 0.12, pt = −3.35, p<0.05). Effectively treating insomnia is associated with reduced SI. Available evidence suggests that Food and Drug Administration (FDA)-approved sedative-hypnotics do not increase the risk of suicidality.

Glucagon-like peptide-1 (GLP-1) is an incretin hormone that modulates glucose metabolism and insulin secretion. Recent translational and clinical research has evaluated the effects of GLP-1 receptor agonists (GLP-1 RAs), a class of drugs that mimic the action of native GLP-1 in the central nervous system (CNS). In addition to the efficacy of GLP-1 for the treatment of diabetes mellitus and obesity, preliminary evidence indicates GLP-1s have neuroprotective, therapeutic, and disease modification effects for select neurodegenerative disorders (e.g. Parkinson's disease, Alzheimer's disease). Among the available GLP-1 RAs, relatively few have been shown to be CNS penetrant. This article synthesizes extant literature reporting on CNS penetrants of GLP-1 RAs as proxied by brain imaging studies. Where available, studies that reported on the bioavailability of GLP-1 RAs in the CNS were identified. A comprehensive search of PubMed, Ovid, and Web of Science from database inception to July 2024 was conducted. Inclusion criteria were English language publications with no date restrictions, preclinical and clinical studies with participants aged 18-80 and studies which focused on GLP-1 RAs including: "Semaglutide" or "Ozempic" or "Rybelsus" or "Wegovy" or "Dulaglutide" or "Trulicity" or "Exenatide" or "Byetta" or "Bydureon" or "Liraglutide" or "Lixisenatide" or "Tirzepatide" or "Mounjaro" or "Zepbound" or "Bydureon BCise" or "Adlyxin" or "Victoza" or "Saxenda". We identified 14 studies that were included in this synthesis. Preclinical studies suggest that select GLP-1 RAs cross the blood-brain barrier (BBB) (i.e. liraglutide, semaglutide, and exenatide). Replicated evidence suggests that CNS penetration of GLP-1 RAs can be proxied by reported effects of GLP-1 RAs on brain connectivity in human participants. Preclinical studies indicate that select GLP-1 RAs are CNS penetrant; whether GLP-1 RAs reproducibly engage neural targets hypothesized to subserve dimensions of psychopathology (e.g., general cognitive functions) remains incompletely characterized.