1,720,969 research outputs found
Dissociation between perception and visuo-motor transformation during reproduction of remembered distances
No full text 1. In complete darkness subjects were presented with two visual stimuli whose distance was randomly varied. The subjects were required to reproduce the interstimulus remembered distance in two conditions. In one condition (reproduction by pointing) they pointed to a virtual position in space. In the other condition (visual reproduction) they used two other visual stimuli. One of them was fixed, and the other could be manually moved. Constant and variable errors were measured in the two conditions. 2. Constant error varied between the two conditions. In the pointing task subjects slightly overestimated the shorter distances, and underestimated the longer ones. During visual reproduction, they consistently overestimated all distances, and the error of overestimation tended to increase with distance. Statistical comparison between the errors in the two conditions was significant. Variable error increased with distance in both conditions, but did not show any significant difference between the two tasks. 3. The results of the present experiment support the hypothesis that perception and visuo-motor transformation are two separate processes in which the same object attributes are independently analysed. However, the finding that variable error did not change between the two tasks suggests that some stages are common to the two processes. </jats:p
A long-term prospective follow-up study of incident RLS in the course of chronic DAergic therapy in newly diagnosed untreated patients with Parkinson's disease
No full textIt is currently controversial if and in which terms Parkinson's disease (PD) and restless legs syndrome (RLS) are linked in co-morbid association. In a cohort of 106 de novo PD patients (67 male and 39 female, aged 42-83 years), 15 of them developed RLS, which was prospectively assessed at 6-month intervals from the starting of dopamine(DA)ergic therapy. The incidence rate of total RLS was 47 per 1,000 case/person per year and 37 per 1,000 case/person per year after the exclusion of possible "secondary" forms of the disorder (n = 3). These figures are higher than those reported in an incidence study conducted in German general population (Study of Health in Pomerania), in which the method of ascertainment of RLS similar to ours has been used. An incidence rate of total RLS significantly higher than that reported in the above-mentioned study was found in the age ranges 55-64 years and in the age range 45-74 years standardized to European general population 2013 (70 and 53 per 1,000 case/person per year, respectively, p < 0.01). Ten out of 12 patients (83.3 %) developed RLS within 24 months from the starting of DAergic medication (median latency 7.5 months). These findings support the view that sustained DAergic therapy could represent the critical factor inducing an increased incidence of RLS in patients with PD and that the latter disease should be regarded as the condition predisposing to the occurrence of the former and not viceversa as previously hypothesized. The mechanism underlying the increased incidence of RLS remains unclear and deserves further investigation
A case-control study of occupational and environmental risk factors for Parkinson's disease in the Emilia-Romagna region of Italy
No full textA questionnaire-based case-control study was carried out on 86 patients with neurologist-confirmed idiopathic Parkinson's disease (PD) and 86 controls similar in sex and age. The control group was recruited in outpatient specialist centers of the same University Hospital (glaucoma, psoriasis vulgaris, essential arterial hypertension and renal diseases). Exposure was defined as occupational or residential contact with a given factor for at least 10 consecutive years prior to the onset of PD. Smoking habits were defined by exclusion of those subjects who never smoked. The following risk factors were identified: cranial trauma (OR: 2.88; 95% CI: 0.98-8.49), well water use (OR: 2.78; 95% CI: 1.46-5.28) and occupational exposure to industrial chemicals (OR: 2.13; 95% CI: 1.16-3.91). Among industrial chemicals, only organic solvents were identified as significant risk factors for PD (O.R. : 2.78, 95% C.I. : 1.23-6.26). Whereas no exposure to neurotoxic metals occurred among controls, making the assessment of the O.R. impossible, exposure pesticides and herbicides was similar in the two groups (O.R. : 1.15; 95% C. : 0.56-2-36). Smoking habits was negatively associated with PD (OR: 0.41; 95% CI: 0.22-0.75), confirming the "protective" role of tobacco smoking suggested by many studies. As a whole, these results support the role of environmental factors in the etiology of PD
Generalized Rhythmic Delta Activity Frontally Predominant Differentiates Dementia With Lewy Bodies From Alzheimer's Disease and Parkinson's Disease Dementia: A Conventional Electroencephalography Visual Analysis
No full textIntroduction. An easily accessible and inexpensive neurophysiological technique such as conventional electroencephalography may provide an accurate and generally applicable biomarker capable of differentiating dementia with Lewy bodies (DLB) from Alzheimer's disease (AD) and Parkinson's disease-associated dementia (PDD). Method. We carried out a retrospective visual analysis of resting-state electroencephalography (EEG) recording of 22 patients with a clinical diagnosis of 19 probable and 3 possible DLB, 22 patients with probable AD and 21 with PDD, matched for age, duration, and severity of cognitive impairment. Results. By using the grand total EEG scoring method, the total score and generalized rhythmic delta activity frontally predominant (GRDAfp) alone or, even better, coupled with a slowing of frequency of background activity (FBA) and its reduced reactivity differentiated DLB from AD at an individual level with an high accuracy similar to that obtained with quantitative EEG (qEEG). GRDAfp alone could also differentiate DLB from PDD with a similar level of diagnostic accuracy. AD differed from PDD only for a slowing of FBA. The duration and severity of cognitive impairment did not differ between DLB patients with and without GRDAfp, indicating that this abnormal EEG pattern should not be regarded as a disease progression marker. Conclusions. The findings of this investigation revalorize the role of conventional EEG in the diagnostic workup of degenerative dementias suggesting the potential inclusion of GRDAfp alone or better coupled with the slowing of FBA and its reduced reactivity, in the list of supportive diagnostic biomarkers of DLB
A long-term echocardiographic study of the course of valvular dysfunctions following discontinuation of ergot-derived dopamine agonists in patients with Parkinson's disease
No full textAbstractBackgroundAn increased risk of restrictive valvular heart disease (VHD) has been widely reported in patients with Parkinson's disease (PD), as a possible consequence of the chronic use of ergot-derived dopamine agonists (EDA), such as pergolide and cabergoline. An aspect that remains poorly investigated is the extent of reversibility of the valvular dysfunction after drug discontinuation.MethodsFifteen patients with PD (8 male and 7 female) on chronic treatment with pergolide or cabergoline in which a cardiac mono or multivalvular fibrosis with or without regurgitation was detected on echocardiographic examination were enrolled in the study from March to December 2007. Because of this the EDA were discontinued and replaced by a non-EDA or l-dopa. A second echocardiography has been performed after a median duration of follow-up of 54months in order to assess the course of valvular abnormalities i.e. regurgitation, thickening of mitral valve anterior leaflet (MAL) and mitral valve tenting area.ResultsAt the follow-up echocardiographic assessment a complete regression of MAL thickening in 7 out of 13 patients and of the aortic fibrosis in 7 out 10 patients was observed. A statistically significant improvement of mitral and tricuspid valve regurgitation score, sum of regurgitations, thickening of MAL and mitral valve tenting area was found. None of the patients showed a worsening of VHD after drug withdrawal.ConclusionsThis long-term study confirms an improvement of the restrictive VHD after withdrawal of EDA in PD patients. However, only a partial reversibility of cardiac valvular abnormalities was observed
A prospective study of the cumulative incidence and course of restless legs syndrome in de novo patients with Parkinson’s disease during chronic dopaminergic therapy
No full textThe authors report the cumulative incidence of Restless Legs Syndrome (RLS) over a 3 years follow-up period in 92 de novo Parkinson’s disease patients under chronic dopaminergic therapy and the clinical course of the sensory-motor disorder over 12 months as from its onset. The overall cumulative incidence of RLS was found by 15.3 %, i.e. 14 incident cases, and by 11.9 %, i.e. 11 incident cases, after the exclusion of possible “secondary” forms of the disorder. These figures are higher than those reported in general population in Germany (Study of Health in Pomerania), confirming our previous findings of incidence rate of the disorder. At the end of the 3 years follow-up period the prevalence of “current” RLS was significantly higher than that previously found in drug naïve Parkinson’s disease patients and in controls, supporting the view that RLS emerging in the course of chronic dopaminergic therapy is the main determinant of the co-morbid association with Parkinson’s disease. During the 12 months period of observation the RLS showed a frequency of occurrence of 6.08 episodes per month on average and a remittent clinical course was prevailing in the 11 incident cases, with a significant frequency decrease in the second as compared to the first 6 months, i.e. 3.26 versus 8.9 episodes per month, and none of the patients developed augmentation in the same period. It is hypothesized that the remittent course could be due to long-term adaptation (downregulation) of the hypersensitive post-synaptic dopamine receptors in the spinal cord to a continuous dopaminergic stimulation, possibly coupled with compensatory up-regulation of pre-synaptic dopamine re-uptake mechanism, in the patients in which the hypothalamic A11 area, site of origin of the dopamine-mediated diencephalo-spinal pathway, is involved in the neurodegenerative process
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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