Monoamine metabolism in the cerebrospinal fluid in Parkinson's disease: relationship to clinical symptoms and subsequent therapeutic outcomes

Non-Motor Symptoms of the Postural Instability and Gait Difficulty Subtype in De Novo Parkinson's Disease Patients: A Cross-Sectional Study in a Single Center

BACKGROUND AND PURPOSE

Little is known about non-motor symptoms (NMSs) associated with the postural instability and gait difficulty (PIGD) phenotype, especially in de novo Parkinson's disease (PD) patients. The aims of this study were to compare NMSs between the tremor dominant (TD) and PIGD phenotypes in de novo PD patients and to determine factors that are associated with the PIGD subtype.

PATIENTS AND METHODS

In a cross-sectional study conducted at our single center, 226 de novo PD patients with a median disease duration of 2 years were recruited. Data, including comprehensive demographics, motor subtypes and NMSs were obtained. Motor subtypes were classified as PIGD and non-PIGD (TD and indeterminate) by Jankovic's method. NMSs were evaluated by the non-motor symptoms questionnaire (NMSQuest).

RESULTS

We identified 73 (32.3%), 34 (15.0%) and 119 (52.7%) patients with TD, intermediate and PIGD subtypes, respectively. Patients with the PIGD subtype had poorer ADL, motor, depression, anxiety, sleep, and non-motor scores compared with those with the TD subtype. In the NMSQuest, the prevalence of cardiovascular, sleep, mood/cognitive and miscellaneous domains was increased in patients with the PIGD subtype compared with patients with the TD subtype. Multivariable forward stepwise logistic regression revealed that the Hamilton Depression Scale (HAMD) [odds ratio (OR), 1.059; 95% confidence interval (CI), 1.016-1.104, p = 0.007] and pain (OR, 3.175; 95% CI, 1.695-5.947, p < 0.001) exhibit significant discriminative power in differentiating PIGD and non-PIGD groups.

CONCLUSION

The PIGD group had more severe cardiovascular symptoms, sleep impairments, mood disturbances and pain. We demonstrated for the first time that pain was associated with the PIGD phenotype. Prompt detection and early treatment of NMSs related to the PIGD phenotype may improve patient outcomes.

Noradrenergic Dysfunction in Alzheimer's and Parkinson's Diseases-An Overview of Imaging Studies

Noradrenergic dysfunction contributes to cognitive impairment in Alzheimer's Disease (AD) and Parkinson's Disease (PD). Conventional therapeutic strategies seek to enhance cholinergic and dopaminergic neurotransmission in AD and PD, respectively, and few studies have examined noradrenergic dysfunction as a target for medication development. We review the literature of noradrenergic dysfunction in AD and PD with a focus on human imaging studies that implicate the locus coeruleus (LC) circuit. The LC sends noradrenergic projections diffusely throughout the cerebral cortex and plays a critical role in attention, learning, working memory, and cognitive control. The LC undergoes considerable degeneration in both AD and PD. Advances in magnetic resonance imaging have facilitated greater understanding of how structural and functional alteration of the LC may contribute to cognitive decline in AD and PD. We discuss the potential roles of the noradrenergic system in the pathogenesis of AD and PD with an emphasis on postmortem anatomical studies, structural MRI studies, and functional MRI studies, where we highlight changes in LC connectivity with the default mode network (DMN). LC degeneration may accompany deficient capacity in suppressing DMN activity and increasing saliency and task control network activities to meet behavioral challenges. We finish by proposing potential and new directions of research to address noradrenergic dysfunction in AD and PD.

Dalfampridine in Parkinson's disease related gait dysfunction: A randomized double blind trial

BACKGROUND

Disease-related gait dysfunction causes extensive disability for persons with Parkinson's disease (PD), with no effective therapies currently available. The potassium channel blocker dalfampridine has been used in multiple neurological conditions and improves walking in persons with multiple sclerosis.

OBJECTIVES

We aimed to evaluate the effect of dalfampridine extended release (D-ER) 10mg tablets twice daily on different domains of walking in participants with PD.

METHODS

Twenty-two participants with PD and gait dysfunction were randomized to receive D-ER 10mg twice daily or placebo for 4weeks in a crossover design with a 2-week washout period. The primary outcomes were change in the gait velocity and stride length.

RESULTS

At 4weeks, gait velocity was not significantly different between D-ER (0.89m/s±0.33) and placebo (0.93m/s±0.27) conditions. The stride length was also similar between conditions: 0.96m±0.38 for D-ER versus 1.06m±0.33 for placebo. D-ER was generally well tolerated with the most frequent side effects being dizziness, nausea and balance problems.

CONCLUSIONS

D-ER is well tolerated in PD patients, however it did not show significant benefit for gait impairment.

Homovanillic acid and 5-hydroxyindole acetic acid as biomarkers for dementia with Lewy bodies and coincident Alzheimer's disease: An autopsy-confirmed study

Dementia with Lewy bodies (DLB) and Alzheimer’s disease (AD) are the two most common causes of dementia. Both pathologies often coexist, and AD patients with concomitant neocortical LB pathology (referred to as the Lewy body variant of AD) generally show faster cognitive decline and accelerated mortality relative to patients with pure AD. Thus, discriminating among patients with DLB, AD, and coincident DLB and AD is important in clinical practice. We examined levels of homovanillic acid (HVA), 5-hydroxyindole acetic acid (5-HIAA), tau, phosphorylated tau (p-tau), and beta-amyloid (Aβ) 1–42 in cerebrospinal fluid (CSF) to evaluate their viability as biomarkers to discriminate among different forms of dementia. We obtained a total of 3498 CSF samples from patients admitted to our hospital during the period from 1996 to 2015. Of these patients, we were able to carry out a brain autopsy in 94 cases. Finally, 78 neuropathologically diagnosed cases (10 AD, six DLB, five DLB with AD, five controls without neurological diseases, and 52 cases with other neurological diseases) were studied. CSF levels of HVA and 5-HIAA were consistently decreased in pathologically advanced Lewy body disorder (LBD; Braak LB stages >3) compared with pathologically incipient LBD (Braak LB stages <2). These results suggest that if an individual has LB pathology in the central nervous system, CSF levels of HVA and 5-HIAA may decrease after the onset of clinical symptoms. In addition, CSF levels of HVA and 5-HIAA decreased with LB pathology, and were especially low in cases of DLB and DLB with AD. Furthermore, the combination of HVA, 5-HIAA, and brain specific proteins t-tau, p-tau, and Aβ 1–42 in CSF were useful for discriminating among DLB, DLB with AD, and AD with high diagnostic accuracy.

Droxidopa and Reduced Falls in a Trial of Parkinson Disease Patients With Neurogenic Orthostatic Hypotension

OBJECTIVES

Droxidopa is a prodrug of norepinephrine indicated for the treatment of orthostatic dizziness, lightheadedness, or the "feeling that you are about to black out" in adult patients with symptomatic neurogenic orthostatic hypotension caused by primary autonomic failure including Parkinson disease (PD). The objective of this study was to compare fall rates in PD patients with symptomatic neurogenic orthostatic hypotension randomized to droxidopa or placebo.

METHODS

Study NOH306 was a 10-week, phase 3, randomized, placebo-controlled, double-blind trial of droxidopa in PD patients with symptomatic neurogenic orthostatic hypotension that included assessments of falls as a key secondary end point. In this report, the principal analysis consisted of a comparison of the rate of patient-reported falls from randomization to end of study in droxidopa versus placebo groups.

RESULTS

A total of 225 patients were randomized; 222 patients were included in the safety analyses, and 197 patients provided efficacy data and were included in the falls analyses. The 92 droxidopa patients reported 308 falls, and the 105 placebo patients reported 908 falls. In the droxidopa group, the fall rate was 0.4 falls per patient-week; in the placebo group, the rate was 1.05 falls per patient-week (prespecified Wilcoxon rank sum P = 0.704; post hoc Poisson-inverse Gaussian test P = 0.014), yielding a relative risk reduction of 77% using the Poisson-inverse Gaussian model. Fall-related injuries occurred in 16.7% of droxidopa-treated patients and 26.9% of placebo-treated patients.

CONCLUSIONS

Treatment with droxidopa appears to reduce falls in PD patients with symptomatic neurogenic orthostatic hypotension, but this finding must be confirmed.

Cerebrospinal fluid biochemical studies in patients with Parkinson's disease: toward a potential search for biomarkers for this disease

The blood-brain barrier supplies brain tissues with nutrients and filters certain compounds from the brain back to the bloodstream. In several neurodegenerative diseases, including Parkinson's disease (PD), there are disruptions of the blood-brain barrier. Cerebrospinal fluid (CSF) has been widely investigated in PD and in other parkinsonian syndromes with the aim of establishing useful biomarkers for an accurate differential diagnosis among these syndromes. This review article summarizes the studies reported on CSF levels of many potential biomarkers of PD. The most consistent findings are: (a) the possible role of CSF urate on the progression of the disease; (b) the possible relations of CSF total tau and phosphotau protein with the progression of PD and with the preservation of cognitive function in PD patients; (c) the possible value of CSF beta-amyloid 1-42 as a useful marker of further cognitive decline in PD patients, and (d) the potential usefulness of CSF neurofilament (NFL) protein levels in the differential diagnosis between PD and other parkinsonian syndromes. Future multicentric, longitudinal, prospective studies with long-term follow-up and neuropathological confirmation would be useful in establishing appropriate biomarkers for PD.

Neurotransmitter receptor density changes in Pitx3ak mice--a model relevant to Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disorder, characterized by alterations of nigrostriatal dopaminergic neurotransmission. Compared to the wealth of data on the impairment of the dopamine system, relatively limited evidence is available concerning the role of major non-dopaminergic neurotransmitter systems in PD. Therefore, we comprehensively investigated the density and distribution of neurotransmitter receptors for glutamate, GABA, acetylcholine, adrenaline, serotonin, dopamine and adenosine in brains of homozygous aphakia mice being characterized by mutations affecting the Pitx3 gene. This genetic model exhibits crucial hallmarks of PD on the neuropathological, symptomatic and pharmacological level. Quantitative receptor autoradiography was used to characterize 19 different receptor binding sites in eleven brain regions in order to understand receptor changes on a systemic level. We demonstrated striking differential changes of neurotransmitter receptor densities for numerous receptor types and brain regions, respectively. Most prominent, a strong up-regulation of GABA receptors and associated benzodiazepine binding sites in different brain regions and concomitant down-regulations of striatal nicotinic acetylcholine and serotonergic receptor densities were found. Furthermore, the densities of glutamatergic kainate, muscarinic acetylcholine, adrenergic α1 and dopaminergic D2/D3 receptors were differentially altered. These results present novel insights into the expression of neurotransmitter receptors in Pitx3(ak) mice supporting findings on PD pathology in patients and indicating on the possible underlying mechanisms. The data suggest Pitx3(ak) mice as an appropriate new model to investigate the role of neurotransmitter receptors in PD. Our study highlights the relevance of non-dopaminergic systems in PD and for the understanding of its molecular pathology.

Treatment of advanced Parkinson’s disease

Parkinson's disease is a progressive neurological disorder characterized by tremor, bradykinesia, rigidity, gait and postural instability and a variety of nonmotor symptoms. While these and other motor signs typically improve with levodopa, the so-called axial signs, such as dysarthria, dysphagia, postural instability and freezing, and most nonmotor signs, such as depression, cognitive decline and dysautonomia, usually do not respond satisfactorily to levodopa. Furthermore, the use of levodopa may be limited by the development of motor fluctuations, dyskinesias and other adverse effects. This manuscript reviews the medical management of advanced Parkinson's disease, focusing on the treatment of motor fluctuations and dyskinesias and of nonmotor and nonlevodopa responsive symptoms.

Nondopaminergic treatments for Parkinson’s disease

SUMMARY The main treatment strategy for Parkinson’s disease (PD) is focused on dopamine replacement. However, PD is no longer seen purely as a disease of the dopaminergic system, as the pathological processes involve neurodegeneration and altered neurotransmission of several nondopaminergic systems that are involved in both motor and nonmotor features of the disease. This article reviews current and experimental nondopaminergic pharmacological approaches to treatments for PD with a focus on motor symptoms, treatments of L-dopa-induced motor complications and treatments of nonmotor symptoms including mood disorders, cognition, psychosis and autonomic problems.

Low dose methylphenidate improves freezing in advanced Parkinson's disease during off-state

Five men with advanced idiopathic Parkinson's disease (PD) were examined to assess the effect of low dose methylphenidate (MPD) on gait. The patients were tested during "off" state before and two hours after the intake of 10 mg MPD while walking an "8 trajectory". The total walking time, total freezing time, number of freezing episodes and the non-freezing walking time were assessed. The obtained data were compared by the Wilcoxon Signed Rank test with a type I error rate of 0.05. The results showed a statistically significant improvement in all gait parameters after MPD intake. Moreover, a good correlation in the grade of improvement for each individual gait characteristic was found. The study demonstrates that low dose of MPD may improve gait, and especially freezing, in patients with severe PD, without the need for exogenous L-dopa. The mechanism of MPD action in patients with advanced PD is further discussed.

Brain Catecholamine Alterations and Pathological Features with Aging in Parkinson Disease Model Rat Induced by Japanese Encephalitis Virus

We analyzed two disease model groups with rats infected by Japanese encephalitis virus (JEV), a 90-day group and a 180-day group after JEV infection. The time measured by the modified pole test showed that motor activities in these two groups were slower than those of age-matched control groups. Striatal dopamine (DA) levels were significantly decreased in all JEV-infected rats. Norepinephrine concentration in brain regions in the 180-day group was significantly decreased in the medulla oblongata and hypothalamus as compared with the control and 90-day group. Tyrosine hydroxylase-positive neurons were significantly decreased in both JEV-infected rat groups. These results suggest that DA decrease and pathological changes in JEV-infected model rats persist for a long time, at least up to 180 days, and this model will be useful for the evaluation of new anti-parkinsonian agents.

Amino acids and biogenic amines in cerebrospinal fluid of patients with Parkinson's disease

To study changes in amino acid metabolism and biogenic amines in Parkinson's disease, we set up a prospective study and measured biogenic amines, their main metabolites, and 22 different amino acids, in cerebrospinal fluid of Parkinson's disease patients (n = 24) and age-matched controls (n = 30). A trend toward higher dopamine levels in Parkinson's disease patients was interpreted as an effect of treatment with levodopa and/or selegiline. Significantly lower concentrations of the dopamine metabolite 3,4-dihydroxyphenylacetic acid in the Parkinson's disease group might reflect dopaminergic cell loss. Our results revealed decreased serotonin catabolism that was interpreted as an effect of treatment with selegiline. Whereas all amino acid levels were unchanged, taurine was significantly lower in Parkinson's disease patients. Studies showed that taurine exerts a trophic action on the central nervous system. In this view, decreased taurine in a neurodegenerative disorder as Parkinson's disease deserves attention.

Chronic exposure to MPTP as a primate model of progressive parkinsonism: a pilot study with a free radical scavenger

The development of a validated primate model of progressive parkinsonism is a critical step in the evaluation of drugs that might halt or slow progression of Parkinson's disease. In this pilot study, we gradually exposed 14 cynomolgus monkeys to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), at a weekly dose of 0.5 mg/kg s.c. for 10 weeks, to determine their probability of not reaching a predetermined endpoint on a disability scale by Kaplan-Meier analysis. Four other MPTP-exposed animals were coadministered the potent free radical scavenger 7-hydroxy-1-[4-(3-methoxyphenyl)-1-piperazinyl]acetylamino-2,2,4,6- tetramethylindan (OPC-14117) as a single oral daily dose of 0.6 g/kg, starting 2 weeks before MPTP initiation. The risk of reaching endpoint by week 10 was 79% and mean time before reaching endpoint was 6 weeks. Global motor activity, recorded in a subset of animals using a portable activity monitor, declined following the first MPTP dose and never recovered. Several cerebrospinal fluid indices of central monoamine metabolism collected by suboccipital puncture at 0, 5, and 10 weeks, including HVA, DOPAC, and tetrahydrobiopterin but not MHPG, were found to be "trait" markers for MPTP exposure, whereas CSF DOPAC and tetrahydrobiopterin constituted potential "state" markers for reaching endpoint. The antioxidant OPC-14117 did not protect against MPTP-induced parkinsonism. Further attempts to validate this incremental model of neurotoxin-induced parkinsonism as a predictor of patient responses to putative neuroprotective agents appear warranted.

Cerebrospinal fluid homovanillic acid levels in rapid-onset dystonia-parkinsonism

Rapid-onset dystonia-parkinsonism (RDP) is characterized by sudden onset over hours to days of dystonia, dysphagia, dysarthria, and parkinsonism. RDP has been reported by our group in two apparently unrelated families. We now report analysis of cerebrospinal fluid metabolites of dopamine, norepinephrine, and serotonin for mild and severely affected individuals, known asymptomatic gene carriers, and at-risk individuals from both families with RDP. Levels of the dopamine metabolite homovanillic acid (HVA) were decreased in severely affected patients and in some asymptomatic gene carriers. HVA levels increased with treatment in some affected individuals, but this increase did not predict clinical response to carbidopa/levodopa. We suggest that a low HVA level is a biological marker with modest association to the diagnosis of RDP.

CSF somatostatin increase in patients with early parkinsonian syndrome

Somatostatin-like immunoreactivity levels (SLI) in cerebrospinal fluid (CSF) were determined in twenty-three patients with untreated parkinsonian syndrome (15 with Idiopathic Parkinson's disease (IPD) and 8 with other forms of parkinsonism) at the moment of clinical diagnosis (mean duration of disease 1.1 +/- 0.2 years), and in 26 subjects without neurological symptoms. None of the IPD patients had a diagnosis of dementia at the moment of inclusion in the study. CSF-SLI content was found to be significantly higher in patients with parkinsonian syndrome (107.9 +/- 9.8 pg/ml) than in control subjects (73.5 +/- 8.4 pg/ml). The increase was also significant when controls were compared with IPD patients. In addition, a positive correlation between SLI and homovanillic acid was found in CSF of all patients. A test of learning memory was used to evaluate the mental state of patients and a significant increase in CSF-somatostatin levels was observed in patients with Idiopathic Parkinson's disease and severe affectation of memory. These results indicate that in the early steps of untreated parkinsonian syndrome, somatostatin concentration in cerebrospinal fluid may increase, probably due to the neurodegenerative depletion of somatostatin from striatal or cortical neurons.

Cerebrospinal dopamine metabolites in rats after intrastriatal administration of 6-hydroxydopamine or 1-methyl-4-phenylpyridinium ion

Dopamine (DA) and its main cerebral metabolites, dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) were measured in striatum and cerebrospinal fluid (CSF) from cisterna magna in rats bilaterally lesioned by intrastriatal administration of 6-hydroxydopamine (6-OHDA) or 1-methyl-4-phenylpyridinium ion (MPP+). 6-OHDA caused a progressive lesion in striatum that is only moderately reflected in the decrease in dopamine metabolite concentration in CSF. MPP+ caused an acute but less selective lesion in the dopamine striatal system, as indicated by a significant reduction in striatal GABA content, followed by a slow recovery in dopamine striatal metabolism and content. The locomotor activity was dramatically reduced in both groups 48 hours after the treatment but remained significantly decreased after two months only in 6-OHDA lesioned animals. A positive correlation was found between HVA CSF concentration and striatal DA content in MPP+ lesioned rats, but not in 6-OHDA lesioned rats. It is concluded that the concentration of dopamine metabolites in CSF can be altered only after a severe striatal lesion: reduction of striatal dopamine content below 50% of normal values and involvement of neuronal or non-neuronal elements other than the dopaminergic system, similarly to the lesions caused by MPP+. These results may partly explain why CSF dopamine metabolites concentrations were significantly decreased both in advanced stages of parkinsonism and in other neurodegenerative disorders.

Concentrations of serotonin and its related substances in the cerebrospinal fluid of parkinsonian patients and their relations to the severity of symptoms

We evaluated the concentrations of free and total serotonin (5-hydroxytryptamine, 5-HT) and its related substances in the cerebrospinal fluid from patients with Parkinson's disease (PD). The concentrations of total 5-HT, 5-hydroxytryptophan, kynurenine and 3-hydroxykynurenine decreased significantly in PD patients compared with controls. The concentration of total 5-HT had significant negative correlations with Hoehn and Yahr's stages, the severity of rigidity, akinesia and gait freezing; the correlation with gait freezing was most conspicuous.

The effects of L-threo-3,4-dihydroxyphenylserine on the total norepinephrine and dopamine concentrations in the cerebrospinal fluid and freezing gait in parkinsonian patients

We studied the effects of L-threo-DOPS (L-DOPS) on the concentrations of total (conjugated and unconjugated) dopamine (DA) and norepinephrine (NE) in the cerebrospinal fluid (CSF) of parkinsonian patients with freezing phenomenon. The NE concentration increased remarkably and dose-dependently after administration of L-DOPS in both L-dopa/carbidopa-pretreated and untreated patients. The DA concentration also increased mildly but significantly in L-dopa/carbidopa-untreated patients. Freezing phenomenon improved in 6 out of 8 patients at Hoehn and Yahr's stage III, and 1 out of 5 patients at stage IV. These results indicate that L-DOPS administration increases the NE concentration dose-dependently, and is effective for freezing of gait of moderate severity.