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Journal of Alzheimer's Disease Reports 2024Identifying the coexistence of Lewy body (LB) pathology with Alzheimer's disease (AD) in clinical practice is important in the era of anti-amyloid-β antibody therapy....
Identifying the coexistence of Lewy body (LB) pathology with Alzheimer's disease (AD) in clinical practice is important in the era of anti-amyloid-β antibody therapy. However, few studies have predicted the presence of comorbid LB pathology with AD using indicative biomarkers of dementia with Lewy bodies or by collecting detailed clinical symptoms. We report the clinical progression of a 67-year-old patient diagnosed with AD who developed rapid eye movement sleep disorder-like symptoms and transient visual hallucinations 10 years after AD onset and was considered to have comorbid LB pathology based on imaging indicative biomarkers of dementia with Lewy bodies.
PubMed: 38746644
DOI: 10.3233/ADR-240019 -
European Journal of Nuclear Medicine... May 2024[I]I-FP-CIT SPECT is an imaging tool to support the diagnosis of parkinsonian syndromes characterized by nigrostriatal dopaminergic degeneration. After intravenous...
PURPOSE
[I]I-FP-CIT SPECT is an imaging tool to support the diagnosis of parkinsonian syndromes characterized by nigrostriatal dopaminergic degeneration. After intravenous injection, [I]I-FP-CIT is metabolized for a small part by the enzyme CYP3A4, leading to the formation of [I]I-nor-β-CIT. [I]I-nor-β-CIT passes the blood-brain barrier and has a very high affinity for the serotonin transporter (SERT). The SERT is expressed in the striatum and cortical areas. So, at least theoretical, the use of frequently used CYP3A4 inhibitors (like amiodarone) may influence the specific to non-specific striatal [I]I-FP-CIT ratio. Here we tested this novel hypothesis.
METHODS
Using a retrospective design, we determined the specific to non-specific striatal [I]I-FP-CIT ratio (using BRASS software) in 6 subjects that were using an CYP3A4 inhibitor and 18 matched controls. Only subjects were included with a normal rated [I]I-FP-CIT SPECT scan, and all participants were scanned on the same brain-dedicated SPECT system.
RESULTS
The specific to non-specific (assessed in the occipital cortex) striatal [I]I-FP-CIT binding ratio was significantly higher in CYP3A4 users than in the control group (3.52 ± 0.33 vs. 2.90 ± 0.78, p < 0.001).
CONCLUSION
Our preliminary data suggest that the use of CYP3A4 inhibitors may influence striatal [I]I-FP-CIT binding ratios. This information, when reproduced in larger studies, may be relevant for studies in which quantification of [I]I-FP-CIT SPECT imaging is used for diagnostic or research purposes.
PubMed: 38730086
DOI: 10.1007/s00259-024-06748-0 -
Neurology and Therapy Jun 2024This pragmatic review synthesises the current understanding of prodromal dementia with Lewy bodies (pDLB) and prodromal Alzheimer's disease (pAD), including clinical...
This pragmatic review synthesises the current understanding of prodromal dementia with Lewy bodies (pDLB) and prodromal Alzheimer's disease (pAD), including clinical presentations, neuropsychological profiles, neuropsychiatric symptoms, biomarkers, and indications for disease management. The core clinical features of dementia with Lewy bodies (DLB)-parkinsonism, complex visual hallucinations, cognitive fluctuations, and REM sleep behaviour disorder are common prodromal symptoms. Supportive clinical features of pDLB include severe neuroleptic sensitivity, as well as autonomic and neuropsychiatric symptoms. The neuropsychological profile in mild cognitive impairment attributable to Lewy body pathology (MCI-LB) tends to include impairment in visuospatial skills and executive functioning, distinguishing it from MCI due to AD, which typically presents with impairment in memory. pDLB may present with cognitive impairment, psychiatric symptoms, and/or recurrent episodes of delirium, indicating that it is not necessarily synonymous with MCI-LB. Imaging, fluid and other biomarkers may play a crucial role in differentiating pDLB from pAD. The current MCI-LB criteria recognise low dopamine transporter uptake using positron emission tomography or single photon emission computed tomography (SPECT), loss of REM atonia on polysomnography, and sympathetic cardiac denervation using meta-iodobenzylguanidine SPECT as indicative biomarkers with slowing of dominant frequency on EEG among others as supportive biomarkers. This review also highlights the emergence of fluid and skin-based biomarkers. There is little research evidence for the treatment of pDLB, but pharmacological and non-pharmacological treatments for DLB may be discussed with patients. Non-pharmacological interventions such as diet, exercise, and cognitive stimulation may provide benefit, while evaluation and management of contributing factors like medications and sleep disturbances are vital. There is a need to expand research across diverse patient populations to address existing disparities in clinical trial participation. In conclusion, an early and accurate diagnosis of pDLB or pAD presents an opportunity for tailored interventions, improved healthcare outcomes, and enhanced quality of life for patients and care partners.
PubMed: 38720013
DOI: 10.1007/s40120-024-00620-x -
Food & Function May 2024Attention-deficit/hyperactivity disorder (ADHD) is a developmental disorder and dopaminergic dysfunction in the prefrontal cortex (PFC) may play a role. Our previous...
Attention-deficit/hyperactivity disorder (ADHD) is a developmental disorder and dopaminergic dysfunction in the prefrontal cortex (PFC) may play a role. Our previous research indicated that theobromine (TB), a methylxanthine, enhances cognitive function in rodents the PFC. This study investigates TB's effects on hyperactivity and cognitive function in stroke-prone spontaneously hypertensive rats (SHR), an ADHD animal model. Male SHRs (6-week old) received a diet containing 0.05% TB for 40 days, while control rats received normal diets. Age-matched male Wistar-Kyoto rats (WKY) served as genetic controls. During the TB administration period, we conducted open-field tests and Y-maze tasks to evaluate hyperactivity and cognitive function, then assessed dopamine concentrations and tyrosine hydroxylase (TH), dopamine receptor D1-5 (DRD1-5), dopamine transporter (DAT), vesicular monoamine transporter-2 (VMAT-2), synaptosome-associated protein-25 (SNAP-25), and brain-derived neurotrophic factor (BDNF) expressions in the PFC. Additionally, the binding affinity of TB for the adenosine receptors (ARs) was evaluated. Compared to WKY, SHR exhibited hyperactivity, inattention and working memory deficits. However, chronic TB administration significantly improved these ADHD-like behaviors in SHR. TB administration also normalized dopamine concentrations and expression levels of TH, DRD2, DRD4, SNAP-25, and BDNF in the PFC of SHR. No changes were observed in DRD1, DRD3, DRD5, DAT, and VMAT-2 expression between SHR and WKY rats, and TB intake had minimal effects. TB was found to have affinity binding to ARs. These results indicate that long-term TB supplementation mitigates hyperactivity, inattention and cognitive deficits in SHR by modulating dopaminergic nervous function and BDNF levels in the PFC, representing a potential adjunctive treatment for ADHD.
Topics: Animals; Rats, Inbred SHR; Male; Rats; Rats, Inbred WKY; Theobromine; Attention Deficit Disorder with Hyperactivity; Memory, Short-Term; Dopamine; Brain-Derived Neurotrophic Factor; Dopamine Plasma Membrane Transport Proteins; Frontal Lobe; Prefrontal Cortex; Tyrosine 3-Monooxygenase; Disease Models, Animal; Synaptosomal-Associated Protein 25
PubMed: 38713055
DOI: 10.1039/d4fo00683f -
NeuroImmune Pharmacology and... Mar 2024HIV-1 Tat (transactivator of transcription) protein disrupts dopaminergic transmission and potentiates the rewarding effects of cocaine. Allosteric modulators of the...
OBJECTIVES
HIV-1 Tat (transactivator of transcription) protein disrupts dopaminergic transmission and potentiates the rewarding effects of cocaine. Allosteric modulators of the dopamine transporter (DAT) have been shown to reverse Tat-induced DAT dysfunction. We hypothesized that a novel DAT allosteric modulator, SRI-30827, would counteract Tat-induced potentiation of cocaine reward.
METHODS
Doxycycline (Dox)-inducible Tat transgenic (iTat-tg) mice and their G-tg (Tat-null) counterparts were tested in a cocaine conditioned place preference (CPP) paradigm. Mice were treated 14 days with saline, or Dox (100 mg/kg/day, i.p.) to induce Tat protein. Upon induction, mice were place conditioned two days with cocaine (10 mg/kg/day) after a 1-h daily intracerebroventricular (i.c.v.) pretreatment with SRI-30827 (1 nmol) or a vehicle control, and final place preference assessed as a measure of cocaine reward.
RESULTS
Dox-treatment significantly potentiated cocaine-CPP in iTat-tg mice over the response of saline-treated control littermates. SRI-30827 treatment eliminated Tat-induced potentiation without altering normal cocaine-CPP in saline-treated mice. Likewise, SRI-30827 did not alter cocaine-CPP in both saline- and Dox-treated G-tg mice incapable of expressing Tat protein.
CONCLUSIONS
These findings add to a growing body of evidence that allosteric modulation of DAT could provide a promising therapeutic intervention for patients with comorbid HIV-1 and cocaine use disorder (CUD).
PubMed: 38711842
DOI: 10.1515/nipt-2023-0022 -
Frontiers in Neurology 2024Diagnosing Dementia with Lewy Bodies (DLB) remains a challenge in clinical practice. The use of I-ioflupane (DaTscan) SPECT imaging, which detects reduced dopamine... (Review)
Review
BACKGROUND
Diagnosing Dementia with Lewy Bodies (DLB) remains a challenge in clinical practice. The use of I-ioflupane (DaTscan) SPECT imaging, which detects reduced dopamine transporter (DAT) uptake-a key biomarker in DLB diagnosis-could improve diagnostic accuracy. However, DAT imaging is underutilized despite its potential, contributing to delays and suboptimal patient management.
METHODS
This review evaluates DLB diagnostic practices and challenges faced within the U.S. by synthesizing information from current literature, consensus guidelines, expert opinions, and recent updates on DaTscan FDA filings. It contrasts DAT SPECT with alternative biomarkers, provides recommendations for when DAT SPECT imaging may be indicated and discusses the potential of emerging biomarkers in enhancing diagnostic approaches.
RESULTS
The radiopharmaceutical I-ioflupane for SPECT imaging was initially approved in Europe (2000) and later in the US (2011) for Parkinsonism/Essential Tremor. Its application was extended in 2022 to include the diagnosis of DLB. DaTscan's diagnostic efficacy for DLB, with its sensitivity, specificity, and predictive values, confirms its clinical utility. However, US implementation faces challenges such as insurance barriers, costs, access issues, and regional availability disparities.
CONCLUSION
I-ioflupane SPECT Imaging is indicated for DLB diagnosis and differential diagnosis of Alzheimer's Disease, particularly in uncertain cases. Addressing diagnostic obstacles and enhancing physician-patient education could improve and expedite DLB diagnosis. Collaborative efforts among neurologists, geriatric psychiatrists, psychologists, and memory clinic staff are key to increasing diagnostic accuracy and care in DLB management.
PubMed: 38711561
DOI: 10.3389/fneur.2024.1395413 -
Journal of Biomolecular Structure &... May 2024In a step towards understanding the structure-property relationship among Synthetic Cathinones (SCs), a combined methodology based on Density Functional Theory (DFT),...
In a step towards understanding the structure-property relationship among Synthetic Cathinones (SCs), a combined methodology based on Density Functional Theory (DFT), Administration, Distribution, Metabolism, Excretion, and Toxicity (ADMET) predictions, docking and molecular dynamics simulations have been applied to correlate physicochemical descriptors of various SCs to their biological activity. The results from DFT and molecular docking studies correlate well with each other explaining the biological activity trends of the studied SCs. Quantum mechanical descriptors viz. polarizability, electron affinity, ionization potential, chemical hardness, electronegativity, molecular electrostatic potential, and ion interaction studies unravel the distinguishingly reactive nature of Group D (pyrrolidine substituted) and Group E (methylenedioxy and pyrrolidine substituted) compounds. According to ADMET analysis, Group D and Group E molecules have a higher probability of permeating through the blood-brain barrier. Molecular docking results indicate that Phe76, Ala77, Asp79, Val152, Tyr156, Phe320, and Phe326 constitute the binding pocket residues of hDAT in which the most active ligands MDPV, MDPBP, and MDPPP are bound. Finally, to validate the derived quantum chemical descriptors and docking results, Molecular Dynamics (MD) simulations are performed with homology-modelled hDAT (human dopamine transporter). The MD simulation results revealed that the majority of SCs remain stable within the hDAT protein's active sites via non-bonded interactions after 100 ns long simulations. The findings from DFT, ADMET analysis, molecular docking, and molecular dynamics simulation studies complement each other suggesting that pyrrolidine-substituted SCs (Group D and E), specifically, MPBP and PVN are proven potent SCs along with MDPV, validating various experimental observations.Communicated by Ramaswamy H. Sarma.
PubMed: 38698732
DOI: 10.1080/07391102.2024.2335303 -
Neuropsychopharmacology : Official... May 2024The catecholamine neuromodulators dopamine and norepinephrine are implicated in motor function, motivation, and cognition. Although roles for striatal dopamine in these...
The catecholamine neuromodulators dopamine and norepinephrine are implicated in motor function, motivation, and cognition. Although roles for striatal dopamine in these aspects of behavior are well established, the specific roles for cortical catecholamines in regulating striatal dopamine dynamics and behavior are less clear. We recently showed that elevating cortical dopamine but not norepinephrine suppresses hyperactivity in dopamine transporter knockout (DAT-KO) mice, which have elevated striatal dopamine levels. In contrast, norepinephrine transporter knockout (NET-KO) mice have a phenotype distinct from DAT-KO mice, as they show elevated extracellular cortical catecholamines but reduced baseline striatal dopamine levels. Here we evaluated the consequences of altered catecholamine levels in NET-KO mice on cognitive flexibility and striatal dopamine dynamics. In a probabilistic reversal learning task, NET-KO mice showed enhanced reversal learning, which was consistent with larger phasic dopamine transients (dLight) in the dorsomedial striatum (DMS) during reward delivery and reward omission, compared to WT controls. Selective depletion of dorsal medial prefrontal cortex (mPFC) norepinephrine in WT mice did not alter performance on the reversal learning task but reduced nestlet shredding. Surprisingly, NET-KO mice did not show altered breakpoints in a progressive ratio task, suggesting intact food motivation. Collectively, these studies show novel roles of cortical catecholamines in the regulation of tonic and phasic striatal dopamine dynamics and cognitive flexibility, updating our current views on dopamine regulation and informing future therapeutic strategies to counter multiple psychiatric disorders.
PubMed: 38698264
DOI: 10.1038/s41386-024-01868-5 -
NPJ Parkinson's Disease May 2024Resilience in neuroscience generally refers to an individual's capacity to counteract the adverse effects of a neuropathological condition. While resilience mechanisms...
Resilience in neuroscience generally refers to an individual's capacity to counteract the adverse effects of a neuropathological condition. While resilience mechanisms in Alzheimer's disease are well-investigated, knowledge regarding its quantification, neurobiological underpinnings, network adaptations, and long-term effects in Parkinson's disease is limited. Our study involved 151 Parkinson's patients from the Parkinson's Progression Marker Initiative Database with available Magnetic Resonance Imaging, Dopamine Transporter Single-Photon Emission Computed Tomography scans, and clinical information. We used an improved prediction model linking neuropathology to symptom severity to estimate individual resilience levels. Higher resilience levels were associated with a more active lifestyle, increased grey matter volume in motor-associated regions, a distinct structural connectivity network and maintenance of relative motor functioning for up to a decade. Overall, the results indicate that relative maintenance of motor function in Parkinson's patients may be associated with greater neuronal substrate, allowing higher tolerance against neurodegenerative processes through dynamic network restructuring.
PubMed: 38697984
DOI: 10.1038/s41531-024-00699-x -
EJNMMI Radiopharmacy and Chemistry May 2024Parkinson's disease is a neurodegenerative disorder that is characterized by a degeneration of the dopaminergic system. Dopamine transporter (DAT) positron emission...
BACKGROUND
Parkinson's disease is a neurodegenerative disorder that is characterized by a degeneration of the dopaminergic system. Dopamine transporter (DAT) positron emission tomography (PET) imaging has emerged as a powerful and non-invasive method to quantify dopaminergic function in the living brain. The PET radioligand, [F]FE-PE2I, a cocaine chemical derivative, has shown promising properties for in vivo PET imaging of DAT, including high affinity and selectivity for DAT, excellent brain permeability, and favorable metabolism. The aim of the current study was to scale up the production of [F]FE-PE2I to fulfil the increasing clinical demand for this tracer.
RESULTS
Thus, a fully automated and GMP-compliant production procedure has been developed using a commercially available radiosynthesis module GE TRACERLab FX2 N. [F]FE-PE2I was produced with a radiochemical yield of 39 ± 8% (n = 4, relative [F]F delivered to the module). The synthesis time was 70 min, and the molar activity was 925.3 ± 763 GBq/µmol (250 ± 20 Ci/µmol). The produced [F]FE-PE2I was stable over 6 h at room temperature.
CONCLUSION
The protocol reliably provides a sterile and pyrogen-free GMP-compliant product.
PubMed: 38696063
DOI: 10.1186/s41181-024-00269-9