Progression of motor symptoms in Parkinson's disease.
ABSTRACT Parkinson's disease (PD) is a chronic progressive neurodegenerative disease that is clinically manifested by a triad of cardinal motor symptoms - rigidity, bradykinesia and tremor - due to loss of dopaminergic neurons. The motor symptoms of PD become progressively worse as the disease advances. PD is also a heterogeneous disease since rigidity and bradykinesia are the major complaints in some patients whereas tremor is predominant in others. In recent years, many studies have investigated the progression of the hallmark symptoms over time, and the cardinal motor symptoms have different rates of progression, with the disease usually progressing faster in patients with rigidity and bradykinesia than in those with predominant tremor. The current treatment regime of dopamine-replacement therapy improves motor symptoms and alleviates disability. Increasing the dosage of dopaminergic medication is commonly used to combat the worsening symptoms. However, the drug-induced involuntary body movements and motor complications can significantly contribute to overall disability. Further, none of the currently-available therapies can slow or halt the disease progression. Significant research efforts have been directed towards developing neuroprotective or disease-modifying agents that are intended to slow the progression. In this article, the most recent clinical studies investigating disease progression and current progress on the development of disease-modifying drug trials are reviewed.
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ABSTRACT: Literature suggests that sex steroid hormones may modify the risk for Parkinson's disease (PD). We investigated the potential effect of reproductive factors on the clinical features of idiopathic PD (IPD) patients. All IPD female patients admitted to and evaluated at our Institute over a 12-month period were included in the present cross-sectional study. We investigated the effect of the following parameters by multivariate linear regression analysis: age at menarche, age at menopause, length of fertile life, duration of exposure to endogenous estrogens and cumulative length of pregnancies, use of contraceptives and hormonal replacement therapy. In total, 579 patients were evaluated and 497 reported menopause before PD onset. In this population, age at PD onset was positively associated with age at menarche and at menopause, length of fertile life and duration of estrogen exposure. Moreover, UPDRS motor score was inversely associated with age at menopause, length of fertile life and duration of estrogen exposure. Increasing age at menarche was also associated with predominant resting tremor at PD onset. In models refitted on patients with early PD (disease duration <5 years; N = 226) all the associations found were confirmed. The relationship between surrogates of estrogen exposure and UPDRS motor score actually became more significant. Our observations support the concept that hormonal exposure of the nigro-striatal network during life may influence its susceptibility to degenerative stimuli in later life, but the association does not seem to be unique? unidirectional. In particular, increased severity of PD signs correlates with shorter duration of estrogen exposure. The underlying mechanisms need to be clarified.Parkinsonism & Related Disorders 08/2013; · 3.27 Impact Factor
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ABSTRACT: The 1-methyl-4-phenyl-1,2,3,4-tetrahydropyridine (MPTP)-induced parkinsonism model, particularly in non-human primates, remains the gold-standard for studying the pathogenesis and assessing novel therapies for Parkinson's disease. However, whether the loss of dopaminergic neurons in this model is progressive remains controversial, mostly due to the lack of objective in vivo assessment of changes in the integrity of these neurons. In the present study, parkinsonism was induced in cynomolgus monkeys by intravenous administration of MPTP (0.2 mg/kg) for 15 days; stable parkinsonism developed over 90 days, when the symptoms were stable. Noninvasive positron emission tomographic neuroimaging of vesicular monoamine transporter 2 with 9-[(18)F] fluoropropyl-(+)-dihydrotetrabenazine ([(18)F]AV-133) was used before, and 15 and 90 days after the beginning of acute MPTP treatment. The imaging showed evident progressive loss of striatal uptake of [(18)F]AV-133. The dopaminergic denervation severity had a significant linear correlation with the clinical rating scores and the bradykinesia subscores. These fi ndings demonstrated that [(18)F]AV-133 PET imaging is a useful tool to noninvasively evaluate the evolution of monoaminergic terminal loss in a monkey model of MPTP-induced parkinsonism.Neuroscience Bulletin 09/2013; · 1.37 Impact Factor
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ABSTRACT: Deep brain stimulation (DBS) is an effective technique for treating Parkinson's disease (PD) in the middle and advanced stages. The subthalamic nucleus (STN) is the most common target for clinical treatment using DBS. While STN-DBS can significantly improve motor symptoms in PD patients, adverse cognitive effects have also been reported. The specific effects of STN-DBS on cognitive function and the related mechanisms remain unclear. Thus, it is imperative to identify the influence of STN-DBS on cognition and investigate the potential mechanisms to provide a clearer view of the various cognitive sequelae in PD patients. For this review, a literature search was performed using the following inclusion criteria: (1) at least 10 patients followed for a mean of at least 6 months after surgery since the year 2006; (2) pre- and postoperative cognitive data using at least one standardized neuropsychological scale; and (3) adequate reporting of study results using means and standard deviations. Of ∼170 clinical studies identified, 25 cohort studies (including 15 self-controlled studies, nine intergroup controlled studies, and one multi-center, randomized control experiment) and one metaanalysis were eligible for inclusion. The results suggest that the precise mechanism of the changes in cognitive function after STN-DBS remains obscure, but STN-DBS certainly has effects on cognition. In particular, a progressive decrease in verbal fluency after STN-DBS is consistently reported and although executive function is unchanged in the intermediate stage postoperatively, it tends to decline in the early and later stages. However, these changes do not affect the improvements in quality of life. STN-DBS seems to be safe with respect to cognitive effects in carefully-selected patients during a follow-up period from 6 months to 9 years.Neuroscience Bulletin 12/2013; · 1.37 Impact Factor