A Comparison among Different Strategies to Detect Potential Unstable Behaviors in Postural Sway.

Assistive Technology helps to assess the daily living and safety of frail people, with particular regards to the detection and prevention of falls. In this paper, a comparison is provided among different strategies to analyze postural sway, with the aim of detecting unstable postural status in standing condition as precursors of potential falls. Three approaches are considered: (i) a time-based features threshold algorithm, (ii) a time-based features Neuro-Fuzzy inference system, and (iii) a Neuro-Fuzzy inference fed by Discrete-Wavelet-Transform-based features. The analysis was performed across a wide dataset and exploited performance indexes aimed at assessing the accuracy and the reliability of predictions provided by the above-mentioned strategies. The results obtained demonstrate valuable performances of the three considered strategies in correctly distinguishing among stable and unstable postural status. However, the analysis of robustness against noisy data highlights better performance of Neuro-Fuzzy inference systems with respect to the threshold-based algorithm.

Understanding the dual-task costs of walking: a StartReact study.

The need to perform multiple tasks more or less simultaneously is a common occurrence during walking in daily life. Performing tasks simultaneously typically impacts task performance negatively. Hypothetically, such dual-task costs may be explained by a lowered state of preparation due to competition for attentional resources, or alternatively, by a 'bottleneck' in response initiation. Here, we investigated both hypotheses by comparing 'StartReact' effects during a manual squeezing task under single-task (when seated) and dual-task (when walking) conditions. StartReact is the acceleration of reaction times by a startling stimulation (a startling acoustic stimulus was applied in 25% of trials), attributed to the startling stimulus directly releasing a pre-prepared movement. If dual-task costs are due to a lowered state of preparation, we expected trials both with and without an accompanying startling stimulus to be delayed compared to the single-task condition, whereas we expected only trials without a startling stimulus to be delayed if a bottleneck in response initiation would underlie dual-task costs. Reaction times of the manual squeezing task in the flexor digitorum superficialis and extensor carpi radialis muscle were significantly delayed (approx. 20 ms) when walking compared to the seated position. A startling acoustic stimulus significantly decreased reaction times of the squeezing task (approx. 60 ms) both when walking and sitting. Dual-task costs during walking are, therefore, likely the result of lowered task preparation because of competition for attentional resources.

Electrocortical networks in Parkinson's disease patients with Mild Cognitive Impairment. The PaCoS study.

INTRODUCTION: Parkinson's Disease (PD) is frequently associated with cognitive dysfunction ranging from Mild Cognitive Impairment (PD-MCI) to dementia. Few electrophysiological studies are available evaluating potential pathogenetic mechanisms linked to cognitive impairment in PD since its initial phases. The objective of the study is to analyze electrocortical networks related with cognitive decline in PD-MCI for identifying possible early electrophysiological markers of cognitive impairment in PD. METHODS: From the PaCoS (Parkinson's disease Cognitive impairment Study) cohort, a sample of 102 subjects including 46 PD-MCI and 56 PD with normal cognition (PD-NC) was selected based on the presence of a neuropsychological assessment and at least one EEG recording. EEG signal epochs were analysed using Independent Component Analysis LORETA and spectral analysis by computing the Power Spectral Density (PSD) of site-specific signal epochs. RESULTS: LORETA analysis revealed significant differences in PD-MCI patients compared to PD-NC, with a decreased network involving alpha activity over the occipital lobe, an increased network involving beta activity over the frontal lobe associated with a reduction over the parietal lobe, an increased network involving theta and delta activity over the frontal lobe and a reduction of networks involving theta and delta activity in the parietal lobe. Quantitative EEG analysis showed a significant decrease of alpha PSD over the occipital regions and an increase of delta PSD over the left temporal region in PD-MCI as compared to PD-NC. CONCLUSION: Electrocortical abnormalities detected in PD-MCI patients may represent the instrumental counterpart of early cognitive decline in PD.

Accuracy of MDS-UPDRS section IV for detecting motor fluctuations in Parkinson's disease.

BACKGROUND: In a precedent paper, we validated part IV of the Unified Parkinson's Disease Rating Scale (UPDRS) for detecting motor fluctuations in Parkinson's Disease (PD) patients using a 12-h Waking-Day Motor Assessment (WDMA) as gold standard, showing a high sensitivity (> 80%) and a lower specificity (< 45%). The aim of this study was to validate the Movement Disorder Society-UPDRS (MDS-UPDRS) part IV, especially items 4.3 and 4.5, using the same methodology. METHODS: PD patients attending the Movement Disorders Clinic at the University Hospital in Catania were consecutively enrolled in the study. A diurnal WDMA was performed to detect motor fluctuations. At each time interval, the motor impairment was evaluated using the motor section of the MDS-UPDRS. Presence or absence of motor fluctuations and the type of motor fluctuation were assessed by four blinded expert raters in movement disorders, by evaluating the graphical representations of the WDMA. We evaluated sensitivity and specificity together with 95% Confidence Interval (CI) of items 4.3 and 4.5, using WDMA as gold standard. RESULTS: We estimated for item 4.3 of the MDS-UPDRS a sensitivity of 74.3% (95% CI 56.7-87.5) and a specificity of 70.6% (95% CI 44-89.7), while for item 4.5, a sensitivity of 67.9% (95% CI 47.6-84.1) and a specificity of 66.7% (95% CI 44.7-84.4). CONCLUSIONS: The present showed a higher specificity level for MDS-UPDRS with respect to the UPDRS, while a slightly lower sensitivity mainly for predictable OFF.

Complexity of electrocortical activity as potential biomarker in untreated Parkinson's disease.

In Parkinson's disease (PD), the identification of instrumental biomarkers is crucial to evaluate disease susceptibility and motor stage. We evaluated self-similarity of electrocortical activity as expression of brain signal complexity in untreated PD, to investigate its possible role as a neurophysiological biomarker. We analyzed the data of 34 untreated PD subjects and 18 group-matched controls who underwent standardized electroencephalography. A Welch's periodogram was applied to site-specific electroencephalographic signal epochs. To investigate self-similarity of electrocortical activity, the power law exponent ß was computed for each selected coordinate. In both PD subjects and controls, ß values at each coordinate increased with an antero-posterior gradient, changing from values around one in fronto-temporal sites to values around two among parieto-occipital sites. PD subjects presented overall lower ß values among different sites compared to controls, with significant differences for the left fronto-temporal sites. Our findings suggest an increased level of fronto-temporal neuronal organization in untreated PD. We hypothesize a possible role of ß as a neurophysiological biomarker for early untreated PD.

Temperament traits and executive functions in Parkinson's disease.

INTRODUCTION: Aim of the study was to evaluate the possible relationship between Temperament traits and executive dysfunction in patients with Parkinson's disease (PD). METHODS: Patients affected by PD diagnosed according to the UK Parkinson's disease Society Brain Bank criteria were enrolled in the study. Patients with a Mini Mental State Examination <24 were excluded from the study. The Temperament and Character Inventory (TCI), a self-report questionnaire assessing the Harm Avoidance (HA), Novelty Seeking (NS) and Reward Dependence (RD) temperamental traits, has been performed. The executive functions were assessed with the Frontal Assessment Battery (FAB). RESULTS: Fifty PD patients (28 men and 22 women; mean age 59.1 ±â€¯10.1 years) were enrolled. High HA (mean score 73.3 ±â€¯24.7) and a low NS score (24.2 ±â€¯18.7) were recorded. Fifteen (30%) patients presented a pathological FAB score (≤13.5). Patients with a pathological FAB score presented an HA score significantly higher than patients with normal FAB score (respectively 84.9 ±â€¯13.7 versus 69.8 ±â€¯26.9; p = 0.045). At the univariate analysis an association between high HA score and pathological FAB score was found (OR 3.85, 95%CI 1.06-13.9; p-value 0.040). CONCLUSION: Our study confirmed an association between executive disturbances and HA in PD patients, possibly related to a common impairment of the frontostriatal circuits.

Dopaminergic and non-dopaminergic gait components assessed by instrumented timed up and go test in Parkinson's disease.

The timed up and go test (TUG) is a widely used clinical test for the evaluation of balance and mobility. An instrumented version of TUG (iTUG) has been proposed to provide quantitative information on TUG performances. Here, we hypothesized that L-dopa may differently influence gait parameters recorded by a portable inertial sensor. To test this idea, we evaluated iTUG test in patients with Parkinson's disease (PD), both in L-dopa OFF and ON state. Twenty-eight PD patients performed the iTUG. Subjects were instructed to perform the task both in practical "OFF" and "ON" state. The system differentiated the test in six phases, recording phase durations, three-axial accelerations, average and peak angular speeds during turning. In all patients, sit-to-stand vertical and medio-lateral accelerations together with turning phase duration and angular speeds improved after L-dopa administration, while sit-to-stand and stand-to-sit phases antero-posterior accelerations were less responsive. In PD, L-dopa modulates iTUG in different ways, mostly improving the turning phases and less acting on postural controls during the sit-to-stand and stand-to-sit phases. Our results suggest different involvement of dopaminergic mechanisms on gait as assessed by iTUG. This is important for those aspects which are not improved by pharmacological therapy.

Quantitative estimation of motor fluctuations in Parkinson's disease.

OBJECTIVES: To provide a quantitative estimation of motor fluctuations in PD through a 12-h Waking-day Motor Assessment (WDMA) and to develop new WDMA-based tools, the Motor Fluctuation Indices. METHODS: Two independent samples of PD patients (exploratory population N = 51, testing population N = 109) were examined. Patients underwent a WDMA using the Unified Parkinson's Disease Rating Scale (UPDRS) and were classified as either having or not having motor fluctuations. To quantify motor fluctuations, the Worsening Index (WI), the Mean Fluctuation Index (MFI) and the Coefficient of Variation (CV) were computed. The optimal cut-off for each index distinguishing patients with or without fluctuations was calculated on the exploratory population. Cut-offs' accuracy was then verified in the testing population. RESULTS: Optimal cut-off scores to differentiate stable patients from fluctuating ones were 8.3 for WI, 5 for MFI and 12.9 for CV. Sensitivity and a specificity were 91.2% (95%CI: 85.9 to 96.5) and 87.8% (95%CI: 81.7 to 93.9) for WI; 75% (95%CI: 66.9 to 83.1) and 90.2% (95%CI: 84.7 to 95.8) for MFI; 69.1% (95%CI: 60.4 to 77.8) and 95.1% (95%CI: 91.1 to 99.2) for CV. Patients with a larger magnitude of fluctuation had higher values for all three indices, whereas patients with multiple daily fluctuations presented only higher WI values. CONCLUSIONS: WDMA-derived Motor Fluctuation Indices may represent reliable tools for evaluating and quantifying the severity of motor fluctuations in PD patients. Even if WDMA is a time-consuming procedure, the detection of Motor Fluctuation Indices could be helpful in assessing therapeutic efficacy on motor fluctuations.

Computer-assisted cognitive rehabilitation on freezing of gait in Parkinson's disease: A pilot study.

BACKGROUND: In Parkinson's Disease (PD), effects of a cognitive training have been systematically evaluated only for cognitive and behavioral outcome measures, with mild to moderate effects. Despite the demonstrated interplay between cognition and gait, no studies have investigated the effect of cognitive rehabilitation protocols on gait in PD. METHODS: Patients affected by PD with freezing of gait were treated twice a week for six weeks with one hour sessions of computer-assisted training of attention ability and information processing tasks. Gait parameters were recorded at baseline, after six weeks and at three months. RESULTS: Seven patients completed the evaluations at six weeks, six patients at three months. We observed at six weeks a significant reduction in both legs cycle duration, with an increment in mean velocity and cadence. Bilateral cycle and step lengths increased even if not significantly. No significant differences in gait parameters were detected at three months with respect to the baseline. CONCLUSIONS: This pilot study suggests that a computer-assisted rehabilitation protocol based on executive functions training could improve walking in PD patients with freezing of gait.

Side effects induced by the acute levodopa challenge in Parkinson's Disease and atypical parkinsonisms.

INTRODUCTION: Acute levodopa challenge may be performed to predict levodopa chronic responsiveness. The aim of the study was to investigate frequency of side effects during the acute levodopa challenge in PD and atypical parkinsonisms. METHODS: We enrolled 34 de novo PD patients and 29 patients affected by atypical parkinsonisms (Multiple System Atrophy, MSA, n = 10; Progressive Supranuclear Palsy, PSP, n = 12 and Corticobasal Degeneration, CBD, n = 7) who underwent an acute levodopa challenge. Side effects occurring during test were recorded. RESULTS: Side effects were more frequent among atypical parkinsonisms as unique group when compared to PD patients (64.3% versus 23.5%; p-value 0.002) with an adjusted OR of 4.36 (95%CI 1.40-13.5). Each atypical parkinsonisms showed almost double occurrence of side effects (MSA 90%, PSP 41.7% and CBD 57%). CONCLUSIONS: Side effects during acute levodopa challenge may be frequent in atypical parkinsonisms. This information could be useful in order to better prepare the patient for the test. Furthermore, it could represent a useful cue in differential diagnosis with PD.

Switching L-dopa Therapy from Pulsatile to Pulse Administration Reduces Motor Complications in Parkinson's Disease.

OBJECTIVE: To evaluate the severity of wearing-off and dyskinesia in patients with complicated Parkinson disease (PD) after switching L-dopa oral therapy from a "pulsatile" administration, consisting in intermittent multiple daily small doses of the drug, to a "pulse" administration, consisting in standard oral doses given at specific interdose intervals. METHODS: Thirty-four PD patients with motor complications were monitored twice with standardized waking day motor status evaluations using the Unified Parkinson Disease Rating Scale-Motor Examination (UPDRS-ME) and the Abnormal Involuntary Movement Scale (AIMS) after switching L-dopa administration modality from "pulsatile" to "pulse." To quantify predictable motor fluctuations, a Wearing Off Index was computed based on changes in treatment response magnitude. RESULTS: On the whole, after switching from "pulsatile" to "pulse" administration, there was a reduction in number of L-dopa daily doses and an increase in the amount of the dosage of the single doses, AIMS maximum score decreased without increasing motor disability. More specifically, in predominant fluctuating patients, there was a significant reduction in UPDRS-ME average score as well as in Wearing Off Index. In predominant dyskinetic patients, there was a significant reduction in average and maximum AIMS scores with no changes in average and maximum UPDRS-ME scores. CONCLUSIONS: Switching L-dopa therapy from "pulsatile" to "pulse" modality may reduce the severity of wearing-off and dyskinesia in complicated PD.

Risk factors in multiple sclerosis: a population-based case-control study in Sicily. Background and methods.

Incidence of multiple sclerosis (MS) has steeply increased over time during the last 30 years in the city of Catania. We carried out a population-based case-control study to evaluate the possible role of both environmental and genetic factors. From 1975 to 2004 in Catania, 367 MS patients diagnosed according to the Poser's criteria had the onset of disease. A sample of MS patients was randomly selected from this incident cohort. Three controls matched by age and sex were randomly selected from the rosters of 14 GPs. Controls were proportionally selected according to the distribution by municipality of the target population using a multistage sampling methods. All cases and controls underwent a face-to-face interview to record information concerning environmental factors and a blood sample was taken for serological and genetic analysis. 164 MS patients (64 % women; mean age of 46.4 ± 10.7) and 481 controls (69 % women; mean age of 47.7 ± 14.8) were enrolled in the study. The distribution of the whole population and the selected controls by municipalities was similar. A blood sample was taken from 150 MS cases and from 337 controls. At the end of the enrolment, we obtained a representative sample of the MS cases and population controls avoiding possible selection bias. Participation rate was very high also concerning the collection of biological specimens.

Secondary task performance during challenging walking tasks and freezing episodes in Parkinson's disease.

Parkinson's disease (PD) patients likely use attentional strategies to compensate for their gait deficits, which increases the cognitive challenge of walking. The interplay between cognitive functions and gait can be investigated by evaluating the subject's attendance to a secondary task during walking. We hypothesized that the ability to attend to a secondary task decreases during challenging walking conditions in PD, particularly during freezing of gait (FOG)-episodes. Twenty-nine PD patients and 14 age-matched controls performed a simple reaction task that involved squeezing a ball as fast as possible in response to an auditory stimulus. Participants performed this reaction task during four conditions: (1) walking at preferred speed; (2) walking with short steps at preferred speed; (3) walking with short steps, as rapidly as possible; (4) making rapid full turns. We used surface electromyography to determine reaction times, and a pressure sensor located within the ball to determine movement onset. Reaction times of PD patients were slower (on average by 42 ms) compared to controls, regardless of the walking task. In both groups, reaction times were significantly longer during the turning condition compared to all other conditions. FOG-episodes were most often seen during the turning condition. In PD patients, reaction times were significantly longer during FOG-episodes compared to trials without FOG. Our results suggest that turning requires more attentional resources than other walking tasks. The observation of delayed reaction times during FOG-episodes compared to trials without FOG suggests that freezers use additional resources to overcome their FOG-episodes.

Does the StartReact Effect Apply to First-Trial Reactive Movements?

INTRODUCTION: StartReact is the acceleration of reaction time by a startling acoustic stimulus (SAS). The SAS is thought to release a pre-prepared motor program. Here, we investigated whether the StartReact effect is applicable to the very first trial in a series of repeated unpractised single-joint movements. METHODS: Twenty healthy young subjects were instructed to perform a rapid ankle dorsiflexion movement in response to an imperative stimulus. Participants were divided in two groups of ten. Both groups performed 17 trials. In one group a SAS (116 dB) was given in the first trial, whereas the other group received a non-startling sound (70 dB) as the first imperative stimulus. In the remaining 16 trials, the SAS was given as the imperative stimulus in 25% of the trials in both groups. The same measurement was repeated one week later, but with the first-trial stimuli counterbalanced between groups. RESULTS: When a SAS was given in the very first trial, participants had significantly shorter onset latencies compared to first-trial responses to a non-startling stimulus. Succeeding trials were significantly faster compared to the first trial, both for trials with and without a SAS. However, the difference between the first and succeeding trials was significantly larger for responses to a non-startling stimulus compared to responses triggered by a SAS. SAS-induced acceleration in the first trial of the second session was similar to that in succeeding trials of session 1. DISCUSSION: The present results confirm that the StartReact phenomenon also applies to movements that have not yet been practiced in the experimental context. The excessive SAS-induced acceleration in the very first trial may be due to the absence of integration of novel context-specific information with the existing motor memory for movement execution. Our findings demonstrate that StartReact enables a rapid release of motor programs in the very first trial also without previous practice, which might provide a behavioural advantage in situations that require a rapid response to a potentially threatening environmental stimulus.

Magnetic resonance parkinsonism index in progressive supranuclear palsy and vascular parkinsonism.

To investigate accuracy of the magnetic resonance parkinsonism index (MRPI) in differentiating progressive supranuclear palsy (PSP) from vascular parkinsonism (VP). We retrospectively analyzed radiological data of 12 PSP patients and 17 VP patients group-matched by age and sex who performed a standardized brain magnetic resonance imaging (MRI). Analysis of selected structures morphometry was performed to all study subjects and the MRPI was calculated for each selected patient. MRI midbrain area as well as superior cerebellar peduncle width were significantly lower in PSP patients compared to VP subjects. MRPI was significantly larger in PSP patients compared to VP subjects. MRPI value ≥13 distinguished the two groups with a sensitivity of 100 % (95 % CI 69.9-100) and a specificity of 100 % (95 % CI 77.1-100). MRPI may represent an accurate tool in differentiating PSP from VP.

Electroencephalographic lateralization, clinical correlates and pharmacological response in untreated Parkinson's disease.

BACKGROUND: In Parkinson's disease (PD), different topographically defined cortical-subcortical oscillatory networks have been implicated in motor program dysfunction. Few studies have focused on clinical correlates of cortical activity asymmetry using quantitative electroencephalography. METHODS: We retrospectively selected N = 34 L-dopa naïve PD subjects who had undergone standardized electroencephalography. We selected N = 18 subjects group-matched by age, sex and hand dominance with normal electroencephalography and no parkinsonism and/or cognitive decline as controls. A Welch's periodogram was applied to electroencephalographic signal epochs recorded from homologous pairs of electrodes over each hemisphere. An index of lateralization was then obtained as the absolute value of the electroencephalographic asymmetry index, computed by subtracting left from right-sided log power spectral density for each homologous site and frequency band. A standardized L-dopa acute challenge test was performed on all PD subjects to compute short-duration response magnitude. RESULTS: In mid/lateral frontal regions higher index of lateralization for the beta band (p = 0.015) and lower index of lateralization for the theta band (p = 0.036) were found in PD subjects as compared to controls. Both parameters correlated with Hoehn-Yahr staging (beta: r = 0.428, p = 0.012; theta: r = -0.464, p = 0.006). In occipital region lower index of lateralization for the alpha band was found in PD correlating with L-dopa short-duration response magnitude (r = 0.456; p = 0.007). CONCLUSIONS: Lateralization of frontal cortex beta electroencephalographic activity is associated with clinical disability. Occipital cortex alpha activity may relate to L-dopa responsiveness in untreated PD subjects.

The walk-bicycle: A new assistive device for Parkinson's patients with freezing of gait?

BACKGROUND: Previous studies reported a preserved ability to cycle in freezers, creating opportunities for restoring mobility and independence. However, use of a bicycle is not always feasible. Here, we investigated the effectiveness of a "walk-bicycle" in reducing freezing of gait (FOG). METHODS: Eighteen Parkinson patients with FOG performed the following tasks, each four times, with and without the walk-bicycle: (1) normal walking; (2) walking with small steps, at normal speed; (3) walking with small steps, as rapidly as possible. RESULTS: Seven patients showed FOG during walking without the walk-bicycle. In those patients, the walk-bicycle afforded a 12% reduction of time frozen (p = 0.026). In 11 patients no FOG was observed during walking without the walk-bicycle. Two of them showed FOG when using the walk-bicycle. CONCLUSIONS: The walk-bicycle may help to reduce FOG in some patients, but not in all. Future studies need to evaluate its usefulness in a home environment.

Obsessive compulsive personality disorder and Parkinson's disease.

OBJECTIVES: To evaluate the frequency of personality disorders in Parkinson's disease (PD) patients and in a group of healthy controls. METHODS: Patients affected by PD diagnosed according to the United Kingdom Parkinson's disease Society Brain Bank diagnostic criteria and a group of healthy controls were enrolled in the study. PD patients with cognitive impairment were excluded from the study. Structured Clinical Interview for Personality Disorders-II (SCID-II) has been performed to evaluate the presence of personality disorders. Presence of personality disorders, diagnosed according to the DSM-IV, was confirmed by a psychiatric interview. Clinical and pharmacological data were also recorded using a standardized questionnaire. RESULTS: 100 PD patients (57 men; mean age 59.0 ± 10.2 years) and 100 healthy subjects (52 men; mean age 58.1 ± 11.4 years) were enrolled in the study. The most common personality disorder was the obsessive-compulsive personality disorder diagnosed in 40 PD patients and in 10 controls subjects (p-value<0.0001) followed by the depressive personality disorder recorded in 14 PD patients and 4 control subjects (p-value 0.02). Obsessive-compulsive personality disorder was also found in 8 out of 16 de novo PD patients with a short disease duration. CONCLUSION: PD patients presented a high frequency of obsessive-compulsive personality disorder that does not seem to be related with both disease duration and dopaminergic therapy.