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International Journal of Molecular... Mar 2023Schizophrenia is a severe psychiatric illness affecting almost 25 million people worldwide and is conceptualized as a disorder of synaptic plasticity and brain... (Review)
Review
Canonical and Non-Canonical Antipsychotics' Dopamine-Related Mechanisms of Present and Next Generation Molecules: A Systematic Review on Translational Highlights for Treatment Response and Treatment-Resistant Schizophrenia.
Schizophrenia is a severe psychiatric illness affecting almost 25 million people worldwide and is conceptualized as a disorder of synaptic plasticity and brain connectivity. Antipsychotics are the primary pharmacological treatment after more than sixty years after their introduction in therapy. Two findings hold true for all presently available antipsychotics. First, all antipsychotics occupy the dopamine D2 receptor (D2R) as an antagonist or partial agonist, even if with different affinity; second, D2R occupancy is the necessary and probably the sufficient mechanism for antipsychotic effect despite the complexity of antipsychotics' receptor profile. D2R occupancy is followed by coincident or divergent intracellular mechanisms, implying the contribution of cAMP regulation, β-arrestin recruitment, and phospholipase A activation, to quote some of the mechanisms considered canonical. However, in recent years, novel mechanisms related to dopamine function beyond or together with D2R occupancy have emerged. Among these potentially non-canonical mechanisms, the role of Na channels at the dopamine at the presynaptic site, dopamine transporter (DAT) involvement as the main regulator of dopamine concentration at synaptic clefts, and the putative role of antipsychotics as chaperones for intracellular D2R sequestration, should be included. These mechanisms expand the fundamental role of dopamine in schizophrenia therapy and may have relevance to considering putatively new strategies for treatment-resistant schizophrenia (TRS), an extremely severe condition epidemiologically relevant and affecting almost 30% of schizophrenia patients. Here, we performed a critical evaluation of the role of antipsychotics in synaptic plasticity, focusing on their canonical and non-canonical mechanisms of action relevant to the treatment of schizophrenia and their subsequent implication for the pathophysiology and potential therapy of TRS.
Topics: Humans; Antipsychotic Agents; Dopamine; Schizophrenia; Schizophrenia, Treatment-Resistant; beta-Arrestins
PubMed: 36983018
DOI: 10.3390/ijms24065945 -
European Journal of Nuclear Medicine... Jun 2023Dopaminergic scintigraphic imaging is a cornerstone to support the diagnosis in dementia with Lewy bodies. To clarify the current state of knowledge on this imaging... (Review)
Review
INTRODUCTION
Dopaminergic scintigraphic imaging is a cornerstone to support the diagnosis in dementia with Lewy bodies. To clarify the current state of knowledge on this imaging modality and its impact on clinical diagnosis, we performed an updated systematic review of the literature.
METHODS
This systematic review was carried out according to PRISMA guidelines. A comprehensive computer literature search of PubMed/MEDLINE, EMBASE, and Cochrane Library databases for studies published through June 2022 was performed using the following search algorithm: (a) "Lewy body" [TI] OR "Lewy bodies" [TI] and (b) ("DaTscan" OR "ioflupane" OR "123ip" OR "123?ip" OR "123 ip" OR "123i-FP-CIT" OR "FPCIT" OR "FP-CIT" OR "beta?CIT" OR "beta CIT" OR "CIT?SPECT" OR "CIT SPECT" OR "Dat?scan*" OR "dat scan*" OR "dat?spect*" OR "SPECT"). Risk of bias and applicability concerns of the studies were evaluated using the QUADAS-2 tool.
RESULTS
We performed a qualitative analysis of 59 studies. Of the 59 studies, 19 (32%) addressed the diagnostic performance of dopamine transporter imaging, 15 (25%) assessed the identification of dementia with Lewy bodies in the spectrum of Lewy body disease and 18 (31%) investigated the role of functional dopaminergic imaging in distinguishing dementia with Lewy bodies from other dementias. Dopamine transporter loss was correlated with clinical outcomes in 19 studies (32%) and with other functional imaging modalities in 15 studies (25%). Heterogeneous technical aspects were found among the studies through the use of various radioligands, the more prevalent being the [123I]N‑ω‑fluoropropyl‑2β‑carbomethoxy‑3β‑(4‑iodophenyl) nortropane (I-FP-CIT) in 54 studies (91.5%). Image analysis used visual analysis (9 studies, 15%), semi-quantitative analysis (29 studies, 49%), or a combination of both (16 studies, 27%).
CONCLUSION
Our systematic review confirms the major role of dopaminergic scintigraphic imaging in the assessment of dementia with Lewy bodies. Early diagnosis could be facilitated by identifying the prodromes of dementia with Lewy bodies using dopaminergic scintigraphic imaging coupled with emphasis on clinical neuropsychiatric symptoms. Most published studies use a semi-quantitative analytical assessment of tracer uptake, while there are no studies using quantitative analytical methods to measure dopamine transporter loss. The superiority of a purely quantitative approach to assess dopaminergic transmission more accurately needs to be further clarified.
Topics: Humans; Lewy Body Disease; Dopamine Plasma Membrane Transport Proteins; Iodine Radioisotopes; Tomography, Emission-Computed, Single-Photon; Tropanes
PubMed: 36920494
DOI: 10.1007/s00259-023-06154-y -
European Journal of Nuclear Medicine... Jun 2023In routine practice, dopamine transporter (DAT) imaging is frequently used as a diagnostic tool to support the diagnosis of Parkinson's disease or dementia with Lewy...
PURPOSE
In routine practice, dopamine transporter (DAT) imaging is frequently used as a diagnostic tool to support the diagnosis of Parkinson's disease or dementia with Lewy bodies. In 2008, we published a review on which medications and drugs of abuse may influence striatal [I]I-FP-CIT binding and consequently may influence the visual read of an [I]I-FP-CIT SPECT scan. We made recommendations on which drugs should be withdrawn before performing DAT imaging in routine practice. Here, we provide an update of the original work based on published research since 2008.
METHODS
We performed a systematic review of literature without language restriction from January 2008 until November 2022 to evaluate the possible effects of medications and drugs of abuse, including the use of tobacco and alcohol, on striatal DAT binding in humans.
RESULTS
The systematic literature search identified 838 unique publications, of which 44 clinical studies were selected. Using this approach, we found additional evidence to support our original recommendations as well as some new findings on potential effect of other medications on striatal DAT binding. Consequently, we updated the list of medications and drugs of abuse that may influence the visual read of [I]I-FP-CIT SPECT scans in routine clinical practice.
CONCLUSION
We expect that a timely withdrawal of these medications and drugs of abuse before DAT imaging may reduce the incidence of false-positive reporting. Nevertheless, the decision to withdraw any medication must be made by the specialist in charge of the patient's care and considering the pros and cons of doing so.
Topics: Humans; Dopamine Plasma Membrane Transport Proteins; Dopaminergic Imaging; Tomography, Emission-Computed, Single-Photon; Tropanes
PubMed: 36847827
DOI: 10.1007/s00259-023-06171-x -
Journal of Neurology, Neurosurgery, and... Apr 2022A number of promising biomarkers for predicting imminent α-synucleinopathies have been suggested in isolated rapid eye movement sleep behaviour disorder (iRBD).... (Meta-Analysis)
Meta-Analysis
BACKGROUND
A number of promising biomarkers for predicting imminent α-synucleinopathies have been suggested in isolated rapid eye movement sleep behaviour disorder (iRBD). However, existing evidence is conflicting without quantitative evaluation.
METHODS
PubMed, Web of Science and ClinicalTrials.gov were searched through June 2021 to identify possible predictors of phenoconversion from iRBD to Parkinson's disease (PD). The pooled HRs and standardised mean differences (SMDs) with 95% CIs were calculated using fixed-effects or random-effects model.
RESULTS
A total of 123 studies were included in the meta-analysis. Significant motor dysfunction (HR 1.83, 95% CI 1.33 to 2.51, I=86.8%, p<0.001), constipation (HR 1.52, 95% CI 1.26 to 1.84, I=8.3%, p=0.365), orthostatic hypotension (HR 1.93, 95% CI 1.05 to 3.53, I=54.9%, p=0.084), hyposmia (HR 2.78, 95% CI 1.83 to 4.23, I=23.9%, p=0.255), mild cognitive impairment (HR 2.27, 95% CI 1.58 to 3.27, I=0%, p=0.681) and abnormal colour vision (SMD -0.34, 95% CI -0.63 to -0.05, I=45.6%, p=0.087) correlated with susceptibility to PD. The process can also be traced by putaminal dopamine transporter imaging (HR 2.60, 95% CI 1.94 to 3.48, I=0%, p=0.781) and tonic electromyographic activity (HR 1.50, 95% CI 1.04 to 2.15, I=70%, p=0.018).
CONCLUSIONS
The predictive value of each biomarker was initially highlighted with comprehensive evaluation. Combining specific predictors with high sensitivity is promising for detecting phenoconversion in the prodromal stage. Large-scale and multicentre studies are pivotal to extend our findings.
Topics: Biomarkers; Cognitive Dysfunction; Humans; Parkinson Disease; Prodromal Symptoms; REM Sleep Behavior Disorder; Synucleinopathies
PubMed: 34937751
DOI: 10.1136/jnnp-2021-328062 -
International Journal of Molecular... Oct 2021Noradrenaline (NE) is a catecholamine acting as both a neurotransmitter and a hormone, with relevant effects in modulating feeding behavior and satiety. Several studies...
Noradrenaline (NE) is a catecholamine acting as both a neurotransmitter and a hormone, with relevant effects in modulating feeding behavior and satiety. Several studies have assessed the relationship between the noradrenergic system and Eating Disorders (EDs). This systematic review aims to report the existing literature on the role of the noradrenergic system in the development and treatment of EDs. A total of 35 studies were included. Preclinical studies demonstrated an involvement of the noradrenergic pathways in binge-like behaviors. Genetic studies on polymorphisms in genes coding for NE transporters and regulating enzymes have shown conflicting evidence. Clinical studies have reported non-unanimous evidence for the existence of absolute alterations in plasma NE values in patients with Anorexia Nervosa (AN) and Bulimia Nervosa (BN). Pharmacological studies have documented the efficacy of noradrenaline-modulating therapies in the treatment of BN and Binge Eating Disorder (BED). Insufficient evidence was found concerning the noradrenergic-mediated genetics of BED and BN, and psychopharmacological treatments targeting the noradrenergic system in AN. According to these data, further studies are required to expand the existing knowledge on the noradrenergic system as a potential target for treatments of EDs.
Topics: Adrenergic Neurons; Animals; Brain; Feeding Behavior; Feeding and Eating Disorders; Humans; Norepinephrine; Norepinephrine Plasma Membrane Transport Proteins
PubMed: 34681746
DOI: 10.3390/ijms222011086 -
Movement Disorders : Official Journal... Aug 2021Dopamine receptors are abundant along the central nigrostriatal tract and are expressed as 5 subtypes in two receptor families. In PD, compensatory changes in dopamine... (Meta-Analysis)
Meta-Analysis Review
Dopamine receptors are abundant along the central nigrostriatal tract and are expressed as 5 subtypes in two receptor families. In PD, compensatory changes in dopamine receptors emerge as a consequence of the loss of dopamine nerve terminals or dopaminergic pharmacotherapy. We performed a systematic review and meta-analysis of the available PET and single-photon emission computed tomography studies that have investigated dopamine receptors in PD, PSP and MSA. The inclusion criteria were studies including human PET or single-photon emission computed tomography imaging; dopamine receptor tracers (D1-like or D2-like) and idiopathic PD, PSP, or MSA patients compared with healthy controls. The 67 included D2-like studies had 1925 patients. Data were insufficient for an analysis of D1-like studies. PD patients had higher striatal binding early in the disease, but after a disease duration of 4.36 years, PD patients had lower binding values than healthy controls. Striatal D2R binding was highest in unmedicated early PD patients and in the striatum contralateral to the predominant motor symptoms. PSP and MSA-P patients had lower striatal D2R binding than PD patients (14.2% and 21.8%, respectively). There is initial upregulation of striatal D2Rs in PD, which downregulate on average 4 years after motor symptom onset, possibly because of agonist-induced effects. The consistent upregulation of D2Rs in the PD striatum contralateral to the predominant motor symptoms indicates that receptor changes are driven by neurodegeneration and loss of striatal neuropil. Both PSP and MSA patients have clearly lower striatal D2R binding values than PD patients, which offers an opportunity for differential diagnostics. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.
Topics: Corpus Striatum; Dopamine; Dopamine Plasma Membrane Transport Proteins; Humans; Parkinson Disease; Receptors, Dopamine D2; Tomography, Emission-Computed, Single-Photon
PubMed: 33955044
DOI: 10.1002/mds.28632 -
European Archives of Psychiatry and... Aug 2021The objective is to understand genetic predisposition to delirium. Following PRISMA guidelines, we undertook a systematic review of studies involving delirium and... (Meta-Analysis)
Meta-Analysis
The objective is to understand genetic predisposition to delirium. Following PRISMA guidelines, we undertook a systematic review of studies involving delirium and genetics in the databases of Pubmed, Scopus, Cochrane Library and PsycINFO, and performed a meta-analysis when appropriate. We evaluated 111 articles, of which 25 were finally included in the analysis. The studies were assessed by two independent researchers for methodological quality using the Downs and Black Tool and for genetic analysis quality. We performed a meta-analysis of 10 studies of the Apolipoprotein E (APOE) gene, obtaining no association with the presence of delirium (LOR 0.18, 95% CI - 0.10-0.47, p = 0.21). Notably, only 5 out of 25 articles met established criteria for genetic studies (good quality) and 6 were of moderate quality. Seven studies found an association with APOE4, the dopamine transporter gene SCL6A3, dopamine receptor 2 gene, glucocorticoid receptor, melatonin receptor and mitochondrial DNA haplotypes. One genome-wide association study found two suggestive long intergenic non-coding RNA genes. Five studies found no association with catechol-o-methyltransferase, melatonin receptor or several interleukins genes. The studies were heterogenous in establishing the presence of delirium. Future studies with large samples should further specify the delirium phenotype and deepen our understanding of interactions between genes and other biological factors.
Topics: Delirium; Genetic Predisposition to Disease; Humans
PubMed: 33779822
DOI: 10.1007/s00406-021-01255-x -
Frontiers in Neuroscience 2020The dopaminergic system is involved in many psychiatric disorders as a GABAergic, serotonergic, and glutamatergic system. A systematic review and meta-analysis was...
The dopaminergic system is involved in many psychiatric disorders as a GABAergic, serotonergic, and glutamatergic system. A systematic review and meta-analysis was performed to elucidate the alteration of the dopaminergic system in anxiety and compulsive disorders. The databases of Pubmed, Embase, and ScienceDirect were searched and articles reporting the involvement of the dopaminergic system in patients with anxiety disorder and obsessive compulsive disorder (OCD) were recognized. The key research data were extracted from the included articles and standardized mean differences were calculated using meta-analyses if there were more than two studies with obtainable data. Sensitivity analyses were further performed to detect the stability of results, and the qualities of all the included studies were assessed using the Newcastle Ottawa scale. Finally, we identified 8 and 11 studies associated with anxiety disorder and OCD for further analysis, respectively. Most consistently, the striatal dopamine D receptor (DR) of OCD patients had decreased while no significant correlation was found between striatal D2R and disease severity. The striatal dopamine transporter (DAT) had not been significantly altered in both the anxiety disorder and OCD patients. The heterogeneity values from the meta-analyses were extremely high while those results remained stable after sensitivity analyses. Inconsistent data were found in the striatal DR of patients with anxiety disorder. Limited data had suggested that dopamine synthesis increased in most regions of the cerebral cortex and cerebellum in OCD patients. The most convincing finding was that the D receptor decreased in patients with obsessive compulsive disorder. The dopamine transporter may have no relationship with anxiety and compulsive disorder.
PubMed: 33343291
DOI: 10.3389/fnins.2020.608520 -
Psychopharmacology Mar 2021Although numerous studies have suggested that pharmacological alteration of the dopamine (DA) system modulates reward discounting, these studies have produced... (Meta-Analysis)
Meta-Analysis
RATIONALE
Although numerous studies have suggested that pharmacological alteration of the dopamine (DA) system modulates reward discounting, these studies have produced inconsistent findings.
OBJECTIVES
Here, we conducted a systematic review and pre-registered meta-analysis to evaluate DA drug-mediated effects on reward discounting of time, probability, and effort costs in studies of healthy rats. This produced a total of 1343 articles to screen for inclusion/exclusion. From the literature, we identified 117 effects from approximately 1549 individual rats.
METHODS
Using random effects with maximum-likelihood estimation, we meta-analyzed placebo-controlled drug effects for (1) DA D1-like receptor agonists and (2) antagonists, (3) D2-like agonists and (4) antagonists, and (5) DA transporter-modulating drugs.
RESULTS
Meta-analytic effects showed that DAT-modulating drugs decreased reward discounting. While D1-like and D2-like antagonists both increased discounting, agonist drugs for those receptors had no significant effect on discounting behavior. A number of these effects appear contingent on study design features like cost type, rat strain, and microinfusion location.
CONCLUSIONS
These findings suggest a nuanced relationship between DA and discounting behavior and urge caution when drawing generalizations about the effects of pharmacologically manipulating dopamine on reward-based decision-making.
Topics: Animals; Biological Transport; Brain; Decision Making; Delay Discounting; Dopamine Agonists; Dopamine Antagonists; Dose-Response Relationship, Drug; Male; Rats; Receptors, Dopamine D1; Receptors, Dopamine D2; Reward
PubMed: 33215269
DOI: 10.1007/s00213-020-05723-5 -
Neuroscience and Biobehavioral Reviews Dec 2020Dopamine has a crucial and well-documented role in the development and maintenance of Gambling Disorder (GD). This systematic review adopts a translational approach... (Review)
Review
Dopamine has a crucial and well-documented role in the development and maintenance of Gambling Disorder (GD). This systematic review adopts a translational approach aimed at providing a comprehensive synthesis of current clinical and preclinical knowledge on dopaminergic function in GD at a neurobiological level. To this end, we present and discuss converging dopaminergic alterations and phenotypes. Preclinical and clinical review protocols were registered on the PROSPERO database (CRD42019124404, CRD42019124405). The literature search was conducted in accordance with PRISMA guidelines using three databases (PubMed, Web of Science, Scopus). We identified 67 preclinical studies using pharmacological and non-pharmacological manipulations of the gambling-like phenotype and 33 human studies investigating either genetic polymorphisms or functional brain imaging data. Dopamine transporter and D2, D3, D4 receptor alterations showed strongest translational concordance. Though no postsynaptic dopaminergic alterations were observed, several studies point at dysfunctions in presynaptic dopamine trafficking in GD, suggestive of hyperdopaminergic states. Developing meaningful translational models is essential to working towards the development of an integrated conceptual framework for GD and neurobiologically-based treatment interventions.
Topics: Dopamine; Gambling; Humans
PubMed: 33035523
DOI: 10.1016/j.neubiorev.2020.09.034