In recent years, iron has been regarded as a common pathological feature of many neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD) and Friedreich's ataxia (FRDA). A number of genes involved in iron transport, storage and regulation have been found associated with initiation and progression of neurodegeneration. However, whether iron abnormalities represent a primary or secondary event still remains unknown. Due to the limitation in transgenic rodent model construction and transfection systems, the progress in unraveling the pathogenic role of different iron-related proteins in neurodegenerative diseases has been slow. Drosophila melanogaster, a simple organism which has a shorter lifespan and smaller genome with many conserved genes, and captures many features of human nervous system and neurodegeneration, may help speed up the progress. The characteristics that spatial- and temporal-specific transgenic Drosophila can be easily constructed and raised in large quantity with phenotype easily determined turn Drosophila into an excellent in vivo genetic system for screening iron-related modifiers in different neurodegenerative conditions and hence provide a better picture about the pathogenic contribution of different iron-related protein abnormalities. It is believed that identification of important iron-related genes that can largely stop or even reverse degenerative process in Drosophila models may lead to development of novel therapeutic strategies against neurodegenerative diseases.
Alzheimer Disease ; physiopathology ; Animals ; Disease Models, Animal ; Drosophila melanogaster ; Friedreich Ataxia ; physiopathology ; Humans ; Iron ; Neurodegenerative Diseases ; physiopathology ; Parkinson Disease ; physiopathology

Pathological neural activity in subthalamic nucleus (STN) is closely related to the symptoms of Parkinson' s disease. Local field potentials (LFPs) recordings from subthalamic nucleus show that power spectral peaks exist at tremor, double tremor and tripble tremor frequencies, respectively. The interaction between these components in the multi-frequency tremor may be related to the generation of tremor. To study the linear and nonlinear relationship between those components, we analyzed STN LFPs from 9 Parkinson's disease patients using time frequency, cross correlation, Granger casuality and bi-spectral analysis. Results of the time-frequency analysis and cross-frequency correlation analysis demonstrated that the power density of those components significantly decreased as the alleviation of tremor and cross-correlation (0.18-0.50) exists during tremor period. Granger causality of the time-variant amplitude showed stronger contribution from tremor to double tremor components, and contributions from both tremor and double tremor components to triple tremor component. Quadratic phase couplings among these three components were detected by the bispectral approaches. The linear and nonlinear relationships existed among the multi-components and certainly confirmed that the dependence cross those frequencies and neurological mechanism of tremor involved complicate neural processes.
Action Potentials ; Electromyography ; Humans ; Parkinson Disease ; physiopathology ; Subthalamic Nucleus ; physiopathology ; Tremor ; physiopathology

Aged ; Apraxias ; physiopathology ; Gait Apraxia ; physiopathology ; Humans ; Parkinson Disease ; diagnosis ; physiopathology

ObjectiveExcessive daytime sleepiness (EDS) is one of the most common sleep abnormalities in patients with Parkinson's disease (PD), yet its multifactorial etiology complicates its treatment. This review summarized recent studies on the epidemiology, etiology, clinical implications, associated features, and evaluation of EDS in PD. The efficacy of pharmacologic and non-pharmacologic treatments for EDS in PD was also reviewed.

Data SourcesEnglish language articles indexed in PubMed and Cochrane databases and Chinese-language papers indexed in Wanfang and National Knowledge Infrastructure databases that were published between January 1987 and November 2017 were located using the following search terms: "sleepiness", "sleep and Parkinson's disease", and "Parkinson's disease and treatment".

Study SelectionOriginal research articles and critical reviews related to EDS in PD were selected.

ResultsEDS is a major health hazard and is associated with many motor and nonmotor symptoms of PD. Its causes are multifactorial. There are few specific guidelines for the treatment of EDS in PD. It is first necessary to identify and treat any possible factors causing EDS. Recent studies showed that some nonpharmacologic (i.e., cognitive behavioral therapy, light therapy, and repetitive transcranial magnetic stimulation) and pharmacologic (i.e., modafinil, methylphenidate, caffeine, istradefylline, sodium oxybate, and atomoxetine) treatments may be effective in treating EDS in PD.

ConclusionsEDS is common in the PD population and can have an immensely negative impact on quality of life. Its causes are multifactorial, which complicates its treatment. Further investigations are required to determine the safety and efficacy of potential therapies and to develop novel treatment approaches for EDS in PD.

Female ; Humans ; Male ; Parkinson Disease ; physiopathology ; Quality of Life ; Sleep Wake Disorders ; physiopathology

Autophagy is a dynamic cellular pathway involved in the turnover of proteins, protein complexes, and organelles through lysosomal degradation. The integrity of postmitotic neurons is heavily dependent on high basal autophagy compared to non-neuronal cells as misfolded proteins and damaged organelles cannot be diluted through cell division. Moreover, neurons contain the specialized structures for intercellular communication, such as axons, dendrites and synapses, which require the reciprocal transport of proteins, organelles and autophagosomes over significant distances from the soma. Defects in autophagy affect the intercellular communication and subsequently, contributing to neurodegeneration. The presence of abnormal autophagic activity is frequently observed in selective neuronal populations afflicted in common neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, Huntington's disease and amyotrophic lateral sclerosis. These observations have provoked controversy regarding whether the increase in autophagosomes observed in the degenerating neurons play a protective role or instead contribute to pathogenic neuronal cell death. It is still unknown what factors may determine whether active autophagy is beneficial or pathogenic during neurodegeneration. In this review, we consider both the normal and pathophysiological roles of neuronal autophagy and its potential therapeutic implications for common neurodegenerative diseases.
Alzheimer Disease/metabolism/pathology/physiopathology ; Animals ; Autophagy/*physiology ; Humans ; Huntington Disease/metabolism/pathology/physiopathology ; Models, Biological ; Neurodegenerative Diseases/metabolism/*pathology/physiopathology ; Neurons/*cytology ; Parkinson Disease/metabolism/pathology/physiopathology

We carried out the Schirmer test to measure objectively the amount of lacrimation among 51 clinically diagnosed parkinsonian patients (33 men and 18 women aged 50 to 79 years, mean 64) and 75 age-matched controls (42 men and 33 women aged 50 to 76, mean 62). Whatman No. 2 paper, prepared in precut strips 5mm by 35mm, was placed in the cul-de-sac for five minutes, after which the wetted length of the strip was studied. It was noted that the lacrimation amount decreased in patients with Parkinson's disease compared with controls: the average amount of lacrimation was 3.4 +/- 2.3mm in the former group and 8.1 +/- 6.5mm in the latter group (p < 0.01). We believe that the decrease in the amount of lacrimation is associated with emotional disturbance and autonomic dysfunction, and presume that the lacrimation may be under the control of the basal ganglia which has a connection with the superior salivatory nucleus downward and the limbic system upward.
Aged ; Autonomic Nervous System/physiopathology ; Female ; Human ; Limbic System/physiopathology ; Male ; Middle Age ; Parkinson Disease/*physiopathology ; Tears/*secretion

BACKGROUNDAlthough thalamotomy could dramatically improve both parkinsonian resting tremor and essential tremor (ET), the mechanisms are obviously different. This study aimed to investigate the neuronal activities in the ventrolateral thalamus of Parkinson's disease (PD) and ET.

METHODSThirty-six patients (PD: 20, ET: 16) were studied. Microelectrode recordings in the ventral oral posterior (Vop) and the ventral intermediate nucleus (Vim) of thalamus was performed on these patients who underwent thalamotomy. Electromyography (EMG) was recorded simultaneously on the contralateral limbs to surgery. Single unit analysis and the interspike intervals (ISIs) were measured for each neuronal type. ISI histogram and auto-correlograms were constructed to estimate the pattern of neuronal firing. Mann-Whitney test and Kruskal-Wallis (K-W) test were used to compare the mean spontaneous firing rate (MSFR) of neurons of PD and ET patients.

RESULTSThree hundred and twenty-three neurons were obtained from 20 PD trajectories, including 151 (46.7%) tremor related neuronal activity, 74 neurons (22.9%) with tonic firing, and 98 (30.4%) neurons with irregular discharge. One hundred and eighty-seven neurons were identified from 16 ET trajectories including 46 (24.6%) tremor-related neuronal activity, 77 (41.2%) neurons with tonic firing, and 64 neurons (34.2%) with irregular discharge. The analysis of MSFR of neurons with tonic firing was 26.7 (3.4 - 68.3) Hz (n = 74) and that of neurons with irregular discharge (n = 98) was 13.9 (3.0 - 58.1) Hz in PD; whereas MSFR of neurons with tonic firing (n = 77) was 48.8 (19.0 - 135.5) Hz and that of neurons with irregular discharge (n = 64) was 26.3 (8.7 - 84.7) Hz in ET. There were significant differences in the MSFR of two types of neuron for PD and ET (K-W test, both P < 0.05). Significant differences in the MSFR of neuron were also obtained from Vop and Vim of PD and ET (16.3 Hz vs. 34.8 Hz, 28.0 Hz vs. 49.9 Hz) (K-W test, both P < 0.05), respectively.

CONCLUSIONIn consistent with recent findings, the decreased MSFR of neurons observed in the Vop is likely to be involved in PD whereas the increased MSFR of neurons seen in the Vim may be a cause of ET.

Essential Tremor ; physiopathology ; Female ; Humans ; Male ; Middle Aged ; Neurons ; physiology ; Parkinson Disease ; physiopathology ; Retrospective Studies ; Ventral Thalamic Nuclei ; physiopathology

BACKGROUNDIt has been proposed that parkinsonian motor signs result from hyperactivity in the output nucleus of the basal ganglia, which suppress the motor thalamus and cortical areas. This study aimed to explore the neuronal activity in the globus pallidus internus (GPi) and the ventrolateral thalamic nuclear group (ventral oral posterior/ventral intermediate, Vop/Vim) in patients with Parkinson's disease (PD).

METHODSTwenty patients with PD who underwent neurosurgery were studied. Microelectrode recording was performed in the GPi (n = 10) and the Vop/Vim (n = 10) intraoperatively. Electromyography (EMG) contralateral to the surgery was simultaneously performed. Single unit analysis was carried out. The interspike intervals (ISI) and coefficient of variation (CV) of ISI were calculated. Histograms of ISI were constructed. A unified Parkinson's disease rating scale (UPDRS) was used to assess the clinical outcome of surgery.

RESULTSThree hundred and sixty-three neurons were obtained from 20 trajectories. Of 175 GPi neurons, there were 15.4% with tremor frequency, 69.2% with tonic firing, and 15.4% with irregular discharge. Of 188 thalamic neurons, there were 46.8% with tremor frequency, 22.9% with tonic firing, and 30.3% with irregular discharge. The numbers of three patterns of neuron in GPi and Vop/Vim were significantly different (P < 0.001). ISI analysis revealed that mean firing rate of the three patterns of GPi neurons was (80.9 +/- 63.9) Hz (n = 78), which was higher than similar neurons with 62.9 Hz in a normal primate. For the Vop/Vim group, ISI revealed that mean firing rate of the three patterns of neurons (n = 95) was (23.2 +/- 17.1) Hz which was lower than similar neurons with 30 Hz in the motor thalamus of normal primates. UPDRS indicated that the clinical outcome of pallidotomy was (64.3 +/- 29.5)%, (83.4 +/- 19.1)% and (63.4 +/- 36.3)%, and clinical outcome of thalamotomy was (92.2 +/- 12.9)%, (68.0 +/- 25.2)% and (44.3 +/- 27.2)% for tremor, rigidity and bradykinesia, respectively. A significant difference of tremor and rigidity was found between GPi and Vop/Vim (P < 0.05).

CONCLUSIONSDifferent changes in neuronal firing rate and the pattern in GPi and Vop/Vim are likely responsible for parkinsonian motor signs. The results support the view that abnormal neuronal activity in GPi and Vop/Vim are involved in the pathophysiology of parkinsonism.

Adult ; Aged ; Female ; Globus Pallidus ; physiopathology ; Humans ; Male ; Middle Aged ; Neurons ; physiology ; Parkinson Disease ; physiopathology ; Ventral Thalamic Nuclei ; physiopathology

BACKGROUNDEpisodic memory includes information about item memory and source memory. Many researches support the hypothesis that these two memory systems are implemented by different brain structures. The aim of this study was to investigate the characteristics of item memory and source memory processing in patients with Parkinson's disease (PD), and to further verify the hypothesis of dual-process model of source and item memory.

METHODSWe established a neuropsychological battery to measure the performance of item memory and source memory. Totally 35 PD individuals and 35 matched healthy controls (HC) were administrated with the battery. Item memory task consists of the learning and recognition of high-frequency national Chinese characters; source memory task consists of the learning and recognition of three modes (character, picture, and image) of objects.

RESULTSCompared with the controls, the idiopathic PD patients have been impaired source memory (PD vs. HC: 0.65 ± 0.06 vs. 0.72 ± 0.09, P = 0.001), but not impaired in item memory (PD vs. HC: 0.65 ± 0.07 vs. 0.67 ± 0.08, P = 0.240).

CONCLUSIONSThe present experiment provides evidence for dissociation between item and source memory in PD patients, thereby strengthening the claim that the item or source memory rely on different brain structures. PD patients show poor source memory, in which dopamine plays a critical role.

Aged ; Cognition ; physiology ; Female ; Humans ; Male ; Memory ; physiology ; Middle Aged ; Neuropsychological Tests ; Parkinson Disease ; physiopathology

When people are walking, they will produce gait signals and different people will produce different gait signals. The research of the gait signal complexity is really of great significance for medicine. By calculating people's gait signal complexity, we can assess a person's health status and thus timely detect and diagnose diseases. In this study, the Jensen-Shannon divergence (JSD), the method of complexity analysis, was used to calculate the complexity of gait signal in the healthy elderly, healthy young people and patients with Parkinson's disease. Then we detected the experimental data by variance detection. The results showed that the difference among the complexity of the three gait signals was great. Through this research, we have got gait signal complexity range of patients with Parkinson's disease, the healthy elderly and healthy young people, respectively, which would provide an important basis for clinical diagnosis.
Aged ; Gait ; Healthy Volunteers ; Humans ; Parkinson Disease ; physiopathology ; Reference Values ; Signal Processing, Computer-Assisted ; Walking