Parkinsonian syndromes: A review

Chemical exchange saturation transfer MRI for neurodegenerative diseases: An update on clinical and preclinical studies

Chemical exchange saturation transfer magnetic resonance imaging is an advanced imaging technique that enables the detection of compounds at low concentrations with high sensitivity and spatial resolution and has been extensively studied for diagnosing malignancy and stroke. In recent years, the emerging exploration of chemical exchange saturation transfer magnetic resonance imaging for detecting pathological changes in neurodegenerative diseases has opened up new possibilities for early detection and repetitive scans without ionizing radiation. This review serves as an overview of chemical exchange saturation transfer magnetic resonance imaging with detailed information on contrast mechanisms and processing methods and summarizes recent developments in both clinical and preclinical studies of chemical exchange saturation transfer magnetic resonance imaging for Alzheimer's disease, Parkinson's disease, multiple sclerosis, and Huntington's disease. A comprehensive literature search was conducted using databases such as PubMed and Google Scholar, focusing on peer-reviewed articles from the past 15 years relevant to clinical and preclinical applications. The findings suggest that chemical exchange saturation transfer magnetic resonance imaging has the potential to detect molecular changes and altered metabolism, which may aid in early diagnosis and assessment of the severity of neurodegenerative diseases. Although promising results have been observed in selected clinical and preclinical trials, further validations are needed to evaluate their clinical value. When combined with other imaging modalities and advanced analytical methods, chemical exchange saturation transfer magnetic resonance imaging shows potential as an in vivo biomarker, enhancing the understanding of neuropathological mechanisms in neurodegenerative diseases.

Isometric tongue endurance and incomplete laryngeal vestibule closure in Parkinson's disease

BACKGROUND

Dysphagia is a common symptom of Parkinson's disease (PD). A delay in laryngeal vestibule closure (LVC) and a reduction in tongue pressure, may affect swallowing safety and increase the risk of pulmonary aspiration.

OBJECTIVE

To verify the relationship between tongue pressure and airway protection in PD patients: (1) comparing tongue pressure measures and physiological events in the pharyngeal phase of swallowing between PD and controls and (2) analysing the association between tongue pressure and LVC in the PD group.

METHODS

Twenty-three patients with idiopathic PD (64.9 years) and 24 healthy controls (64.1 years) participated in this study. All participants underwent the following procedures to verify tongue pressure measurements using the Iowa Oral Performance Instrument: maximum anterior and posterior pressure, isotonic and isometric tongue endurance and anterior and posterior tongue pressure during saliva swallowing. To verify swallowing safety, videofluoroscopic swallowing studies focusing on the pharyngeal phase were performed based on the MBSImP protocol.

RESULTS

Compared to healthy controls, PD exhibited a statistically significant decline in tongue pressure tasks: posterior maximum pressure, isotonic endurance, anterior and posterior isometric endurance and tongue pressure during posterior swallowing. Patients with PD had worse pharyngeal scores, including LVC scores, than controls. PD and incomplete LVC had lower anterior isometric endurance scores when compared to those with complete LVC.

CONCLUSION

PD with incomplete LVC scored lower in the anterior isometric endurance task. We observed a potential clinical use of this task for the assessment and management of dysphagia in patients with PD.

Dopamine D3 Receptor in Parkinson Disease: A Prognosis Biomarker and an Intervention Target

Parkinson disease (PD) dementia, pathologically featured as nigrostriatal dopamine (DA) neuronal loss with motor and non-motor manifestations, leads to substantial disability and economic burden. DA therapy targets the DA D3 receptor (D3R) with high affinity and selectivity. The pathological involvement of D3R is evidenced as an effective biomarker for disease progression and DA agnostic interventions, with compensations of increased DA, decreased aggregates of α-synuclein (α-Syn), enhanced secretion of brain-derived neurotrophic factors (BDNF), attenuation of neuroinflammation and oxidative damage, and promoting neurogenesis in the brain. D3R also interacts with D1R to reduce PD-associated motor symptoms and alleviate the side effects of levodopa (L-DOPA) treatment. We recently found that DA D2 receptor (D2R) density decreases in the late-stage PDs, while high D3R or DA D1 receptor (D1R) + D3R densities in the postmortem PD brains correlate with survival advantages. These new essential findings warrant renewed investigations into the understanding of D3R neuron populations and their cross-sectional and longitudinal regulations in PD progression.

Clinical outcomes and cognitive impairments between progressive supranuclear palsy and multiple system atrophy

BACKGROUND

Both progressive supranuclear palsy (PSP) and multiple system atrophy (MSA) belong to atypical parkinsonian syndromes. It is important to differentiate these diseases accurately. We compared clinical outcomes and cognitive impairments between PSP and MSA.

METHODS

Eighty-five MSA parkinsonism type (MSA-P) patients and 76 PSP patients participated in this research. The Montreal Cognitive Assessment (MoCA) and the mini-mental state examination (MMSE) evaluated cognitive function.

RESULTS

MSA-P patients had a significantly higher incidence of dyskinesia, fall, urinary symptoms, and constipation, whereas patients with PSP had a higher incidence of tremor and salivation. MSA-P patients had higher MMSE and MoCA scores than PSP patients. The MMSE score showed a diagnostic cut-off score of 24.5 in PSP versus MSA-P. The MoCA score showed a diagnostic cut-off score of 20.5 in PSP versus MSA-P.

CONCLUSION

In conclusion, patients with PSP had differences in the clinical outcomes and cognitive impairments compared with MSA-P patients. PSP patients had more severe cognitive deficits. The score of MMSE and MoCA could be used in distinguishing MSA-P from PSP.

Lactobacillus plantarum DP189 Reduces α-SYN Aggravation in MPTP-Induced Parkinson's Disease Mice via Regulating Oxidative Damage, Inflammation, and Gut Microbiota Disorder

This study aimed to evaluate the attenuating effect of Lactobacillus plantarum DP189 on α-synuclein (α-SYN) aggregates in the substantia nigra (SN) of Parkinson's disease (PD) mice via 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced. Our results indicated that L. plantarum DP189 increased the levels of superoxide dismutase (SOD), glutathione peroxide (GSH-Px), and interleukin-10 (IL-10) and decreased the levels of malondialdehyde (MDA), reactive oxygen species (ROS), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-1β (IL-1β). Moreover, L. plantarum DP189 reduced the α-SYN accumulation in SN. Mechanistically, L. plantarum DP189 activated the expression of nuclear factor erythroid 2-related factor (Nrf2)/ARE and PGC-1α pathways and suppressed the NLRP3 inflammasome. Furthermore, fecal analysis showed that L. plantarum DP189 reshaped the gut microbiota in PD mice by reducing the number of pathogenic bacteria (Proteobacteria and Actinobacteria) and increased the abundance of probiotics (Lactobacillus and Prevotella). Our results suggested that L. plantarum DP189 could delay the neurodegeneration caused by the accumulation of α-SYN in the SN of PD mice via suppressing oxidative stress, repressing proinflammatory response, and modulating gut microbiota.

Dopamine D3 Receptors: A Potential Target to Treat Motivational Deficits in Parkinson's Disease

Parkinson's disease (PD), which is traditionally viewed as a motor disorder involving the degeneration of dopaminergic (DA) neurons, has recently been identified as a quintessential neuropsychiatric condition. Indeed, a plethora of non-motor symptoms may occur in PD, including apathy. Apathy can be defined as a lack of motivation or a deficit of goal-directed behaviors and results in a pathological decrease of self-initiated voluntary behavior. Apathy in PD appears to fluctuate with the DA state of the patients, suggesting a critical role of DA neurotransmission in the pathophysiology of this neuropsychiatric syndrome. Using a lesion-based approach, we developed a rodent model which exhibits specific alteration in the preparatory component of motivational processes, reminiscent to apathy in PD. We found a selective decrease of DA D₃ receptors (D₃R) expression in the dorsal striatum of lesioned rats. Next, we showed that inhibition of D₃R neurotransmission in non-lesioned animals was sufficient to reproduce the motivational deficit observed in our model. Interestingly, we also found that pharmacologically targeting D₃R efficiently reversed the motivational deficit induced by the lesion. Our findings, among other recent data, suggest a critical role of D₃R in parkinsonian apathy and highlight this receptor as a promising target for treating motivational deficits.

Pramipexole regulates depression-like behavior via dopamine D3 receptor in a mouse model of Parkinson's disease

Depression is one of the strongest predictors of quality of life in patients with Parkinson's disease (PD). Despite the high prevalence of depression, there is no clear guidance for its treatment in PD because the evidence for the efficacy of most antidepressants remains insufficient. Pramipexole, a dopamine agonist, is one of the few drugs that has proven to be clinically useful. However, the underlying mechanisms of antidepressive effects of pramipexole are still unknown. A 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model, dopamine D2 receptor (DRD2) and D3 receptor (DRD3) knockout mice were used in our study. Compared with other dopamine D2-like receptor agonists and madopar, pramipexole improved depression-like behavior and alleviate bradykinesia in an MPTP-induced mouse model of PD. Pramipexole significantly improved depression-like behavior in DRD2^-/- mice but not in DRD3^-/- mice. These results demonstrate that the antidepressive effect of pramipexole is mediated by DRD3 but not DRD2. Our findings highlight the need to develop novel dopamine agonists specifically targeting DRD3 for the treatment of depression in PD in the future.

The Impact of SNCA Variations and Its Product Alpha-Synuclein on Non-Motor Features of Parkinson's Disease

Parkinson’s disease (PD) is a common and progressive neurodegenerative disease, caused by the loss of dopaminergic neurons in the substantia nigra pars compacta in the midbrain, which is clinically characterized by a constellation of motor and non-motor manifestations. The latter include hyposmia, constipation, depression, pain and, in later stages, cognitive decline and dysautonomia. The main pathological features of PD are neuronal loss and consequent accumulation of Lewy bodies (LB) in the surviving neurons. Alpha-synuclein (α-syn) is the main component of LB, and α-syn aggregation and accumulation perpetuate neuronal degeneration. Mutations in the α-syn gene (SNCA) were the first genetic cause of PD to be identified. Generally, patients carrying SNCA mutations present early-onset parkinsonism with severe and early non-motor symptoms, including cognitive decline. Several SNCA polymorphisms were also identified, and some of them showed association with non-motor manifestations. The functional role of these polymorphisms is only partially understood. In this review we explore the contribution of SNCA and its product, α-syn, in predisposing to the non-motor manifestations of PD.

The Effects of a 10-Week Home-Based Exercise Programme in Individuals with Parkinson’s Disease during the COVID-19 Pandemic: A Pilot Study

Current restrictions on clinical visits as a consequence of the COVID-19 pandemic has increased the need for home-based exercise regimes to facilitate useful, long term patterns of behaviour in individuals with Parkinson’s disease (PD). This study aimed to evaluate the effectiveness of a 10-week home-based exercise program designed to target improvements in axial rigidity and gait. The Movement Disorders Society-Unified Parkinson’s Disease Rating Scale (MDS-UPDRS), motor scale and rigidity items, Functional axial rotation–physical (FAR-p), functional reach test (FRT), and time up and go (TUG) test were recorded. In addition, the 10-metre walk test, the fall efficacy scale international (FES-I) and the global rating of change score (GROC) were also recorded. Eighteen individuals were divided randomly into two groups: a home-based exercise group (n = 10) and a traditional physiotherapy control group (n = 8). Participants in the 10-week home-based exercise group showed significant improvements (p < 0.05) in the MDS-UPDRS rigidity item, FAR-p, step length, gait velocity, FRT and FES-I when compared with the control group. This study supports the use of home-based exercises in individuals with PD. These preliminary results also support the hypothesis that targeting axial deficits may be an effective approach for improving gait and reducing falls.

LC-MS/MS Determination of Modified Nucleosides in The Urine of Parkinson's Disease and Parkinsonian Syndromes Patients

Epigenetic modifications play a key role in gene regulation and expression and are involved in numerous cellular processes. Due to the limited research on nucleosides in Parkinson's disease (PD), it is very important to consider epigenetic factors and their role in the development of PD. The aim of this study was to investigate and compare the levels of modified nucleosides, such as O-methylguanosine, N⁶-methyl-2'-deoxyadenosine, 1-methyladenosine, 1-methylguanine, 7-methylguanine, 3-methyladenine and 7-methylguanosine in the urine of Parkinson's disease (PD) patients and the control group, and to verify that the results obtained differ in a subgroup of patients with parkinsonian syndromes. The study group comprised 18 patients with diagnosed idiopathic Parkinson's disease and four parkinsonian syndromes. The control group consisted of 30 age- and sex-matched neurological patients without confirmation by neuroimaging brain damage and extrapyramidal symptoms. The levels of nucleosides were determined by validated liquid chromatography coupled with the mass spectrometry (LC-MS/MS) method using the multiple reaction monitoring (MRM) mode. Lower levels of O-methylguanosine, 3-methyladenine, 1-methylguanine, N⁶-methyl-2'-deoxyadenosine and a higher level of 7-methylguanine in the urine of 22 PD patients were observed. Moreover, elevated levels of 1-methyladenosine, 7-methylguanine, and O-methylguanosine were observed in the parkinsonian syndrome subgroup. These preliminary results may indicate that modified nucleosides describe metabolic disturbances in the metabolism of purine, which was the most severely affected pathway that mediated the detrimental effects of neuroinflammation on PD.

Discriminative pattern of reduced cerebral blood flow in Parkinson's disease and Parkinsonism-Plus syndrome: an ASL-MRI study

BACKGROUND

Accurate identification of Parkinson's disease (PD) and Parkinsonism-Plus syndrome (PPS), especially in the early stage of the disease, is very important. The purpose of this study was to investigate the discriminative spatial pattern of cerebral blood flow (CBF) between patients with PD and PPS.

METHODS

Arterial spin labeling (ASL) perfusion-weighted imaging was performed in 20 patients with PD (mean age 56.35 ± 7.56 years), 16 patients with PPS (mean age 59.62 ± 6.89 years), and 17 healthy controls (HCs, mean age 54.17 ± 6.58 years). Voxel-wise comparison of the CBF was performed among PD, PPS, and HC groups. The receiver operating characteristic (ROC) curve was used to evaluate the performance of CBF in discriminating between PD and PPS. The relationship between CBF and non-motor neuropsychological scores was assessed by correlation analysis.

RESULTS

PD group showed a significantly decreased CBF in the right cerebelum_crus2, the left middle frontal gyrus (MFG), the triangle inferior frontal gyrus (IFG_Tri), the left frontal medial orbital gyrus (FG_Med_Orb) and the left caudate nucleus (CN) compared with the HC group (P < 0.05). Besides the above regions, the left supplementary motor area (SMA), the right thalamus had decreased CBF in the PPS group compared with the HC group (P < 0.05). PPS group had lower CBF value in the left MFG, the left IFG_Tri, the left CN, the left SMA, and the right thalamus compared with the PD group (P < 0.05). CBFs in left IFG_Tri, the left CN, the left SMA, and the right thalamus had moderate to high capacity in discriminating between PD and PPS patients (AUC 0.719-0.831). The CBF was positively correlated with the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) scores in PD patients, while positively correlated with the MMSE, Hamilton Anxiety Scale (HAMA), Hamilton Depression Scale (HAMD) scores in PPS patients (P < 0.05).

CONCLUSION

PD and PPS patients have certain discriminative patterns of reduced CBFs, which can be used as a surrogate marker for differential diagnosis.

Parkinsonism with newly diagnosed flare-up rheumatoid arthritis mimicking progressive supranuclear palsy

In order to make a correct diagnosis of idiopathic Parkinson's disease (PD), it is essential to exclude atypical parkinsonian features, such as early dementia, fall, and autonomic dysfunction. Rheumatoid arthritis (RA), which is a systemic inflammatory disorder, although most patients present in a polyarticular manner. Still some may also present with extra-articular involvement including skin, lung, heart, and the central or peripheral nervous systems. A possible pathogenetic link between RA and PD are proposed. However, the coexistence of RA and progressive supranuclear palsy (PSP) is rarely reported. Here, we report a parkinsonian patient with a newly diagnosed flare-up RA presenting with early falls, postural instability and supra-nuclear gaze palsy, which suggestive of clinically probable PSP. Furthermore, the parkinsonian features respond to anti-rheumatic agents, but not levodopa. Finally, the patient looks like a clinical possible PD. In summary, Parkinsonian patient with newly diagnosed flare-up RA can present with clinically probable PSP. Unbearably painful limb contracture is a clue of the coexistence of RA. Both typical and atypical parkinsonian features respond dramatically to anti-rheumatic medication, but not levodopa.

Dopamine D3 receptor: A neglected participant in Parkinson Disease pathogenesis and treatment?

Parkinson disease (PD) is a neurodegenerative disorder characterized by motor and non-motor symptoms which relentlessly and progressively lead to substantial disability and economic burden. Pathologically, these symptoms follow the loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc) associated with abnormal α-synuclein (α-Syn) deposition as cytoplasmic inclusions called Lewy bodies in pigmented brainstem nuclei, and in dystrophic neurons in striatal and cortical regions (Lewy neurites). Pharmacotherapy for PD focuses on improving quality of life and primarily targets dopaminergic pathways. Dopamine acts through two families of receptors, dopamine D1-like and dopamine D2-like; dopamine D3 receptors (D3R) belong to dopamine D2 receptor (D2R) family. Although D3R's precise role in the pathophysiology and treatment of PD has not been determined, we present evidence suggesting an important role for D3R in the early development and occurrence of PD. Agonist activation of D3R increases dopamine concentration, decreases α-Syn accumulation, enhances secretion of brain derived neurotrophic factors (BDNF), ameliorates neuroinflammation, alleviates oxidative stress, promotes neurogenesis in the nigrostriatal pathway, interacts with D1R to reduce PD associated motor symptoms and ameliorates side effects of levodopa (L-DOPA) treatment. Furthermore, D3R mutations can predict PD age of onset and prognosis of PD treatment. The role of D3R in PD merits further research. This review elucidates the potential role of D3R in PD pathogenesis and therapy.

Probiotics May Have Beneficial Effects in Parkinson's Disease: In vitro Evidence

Background: Parkinson's disease (PD) is characterized by loss of dopaminergic neurons and intraneuronal accumulation of alpha-synuclein, both in the basal ganglia and in peripheral sites, such as the gut. Peripheral immune activation and reactive oxygen species (ROS) production are important pathogenetic features of PD. In this context, the present study focused on the assessment of in vitro effects of probiotic bacterial strains in PBMCs isolated from PD patients vs. healthy controls.

Methods: 40 PD patients and 40 matched controls have been enrolled. Peripheral blood mononuclear cells (PBMCs) were isolated and co-cultured with a selection of probiotics microorganisms belonging to the lactobacillus and bifidobacterium genus. In vitro release of the major pro- (Tumor Necrosis Factor-alpha and Interleukin-17A and 6) and anti-inflammatory (Interleukin 4 and 10) cytokines by PBMCs, as well as the production of ROS was investigated. Furthermore, we assessed the ability of probiotics to influence membrane integrity, antagonize the growth of potential pathogen bacteria, such as Escherichia coli and Klebsiella pneumoniae and encode tyrosine decarboxylase genes (tdc).

Results: All probiotic strains were able to inhibit inflammatory cytokines and ROS production in both patients and controls. The most striking results were obtained in PD subjects with L. salivarius LS01 and L. acidophilus which significantly reduced pro-inflammatory and increased the anti-inflammatory cytokines (p < 0.05). Furthermore, most strains determined restoration of membrane integrity and inhibition of E. coli and K. pneumoniae. Finally, we also showed that all the strains do not carry tdc gene, which is known to decrease levodopa bioavailability in PD patients under treatment.

Conclusions: Probiotics exert promising in vitro results in decreasing pro-inflammatory cytokines, oxidative stress and potentially pathogenic bacterial overgrowth. In vivo longitudinal data are mandatory to support the use of bacteriotherapy in PD.