66 research outputs found

    Derivation and Analysis of Dynamic Handwriting Features as Clinical Markers of Parkinson’s Disease

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    Parkinson’s Disease (PD) is a complex neurodegenerative disorder that is challenging to diagnose. Recent research has demonstrated predictive value in the analysis of dynamic handwriting features for detecting PD, however, consensus on clinically-useful features is yet to be reached. Here we explore and evaluate secondary kinematic handwriting features hypothesized to be diagnostically relevant to Parkinson’s Disease using a publicly-available Spiral Drawing Test PD dataset. Univariate and multivariate analysis was performed on derived features. Classification outcome was determined using logistic regression models with 10-fold cross validation. Feature correlation was based on model specificity and sensitivity. Variations in grip angle, instantaneous acceleration and pressure indices were found to have high predictive potential as clinical markers of PD, with combined classification accuracy of above 90%. Our results show that the significance of secondary handwriting features and recommend the feature expansion step for hypothesis generation, comparative evaluation of test types and improved classification accuracy

    BeCAPTCHA: Behavioral bot detection using touchscreen and mobile sensors benchmarked on HuMIdb

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    In this paper we study the suitability of a new generation of CAPTCHA methods based on smartphone interactions. The heterogeneous flow of data generated during the interaction with the smartphones can be used to model human behavior when interacting with the technology and improve bot detection algorithms. For this, we propose BeCAPTCHA, a CAPTCHA method based on the analysis of the touchscreen information obtained during a single drag and drop task in combination with the accelerometer data. The goal of BeCAPTCHA is to determine whether the drag and drop task was realized by a human or a bot. We evaluate the method by generating fake samples synthesized with Generative Adversarial Neural Networks and handcrafted methods. Our results suggest the potential of mobile sensors to characterize the human behavior and develop a new generation of CAPTCHAs. The experiments are evaluated with HuMIdb1 (Human Mobile Interaction database), a novel multimodal mobile database that comprises 14 mobile sensors acquired from 600 users. HuMIdb is freely available to the research communityThis work has been supported by projects: PRIMA, Spain (H2020-MSCA-ITN-2019-860315), TRESPASS-ETN, Spain (H2020-MSCA-ITN-2019-860813), BIBECA RTI2018-101248-B-I00 (MINECO/FEDER), and BioGuard, Spain (Ayudas Fundación BBVA a Equipos de Investigación Científica 2017). Spanish Patent Application P20203006

    The Objective Measurement of Sleep-Wake Disturbance in Parkinson's Disease

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    Parkinson’s disease (PD) is an increasingly prevalent neurodegenerative disease affecting older adults. Motor symptoms, including tremor, rigidity and tremor were classically predominant. However, troublesome non-motor symptomatology are known to impair quality of life for patients with PD and there carers. Sleep-wake disturbances are gaining attention in PD encompassing disturbances of the circadian, homeostatic and ultradian sleep systems. These symptoms have been linked to the troublesome problems of cognitive deficits, mood disturbance and visual hallucinations. Mechanisms exploring the interaction of sleep-wake disturbance and other non-motor symptoms in PD are not well understood. Bidirectional causality between sleep-wake disturbance and concomitant symptoms in PD provide insights into common chemical and neural mechanisms which prior to the development of therapy, must be understood. Furthermore, sleep-wake disorders in PD at present provide a maker of early diagnosis for which future disease modifying treatment can be targeted. However objective and reliable measurement techniques are yet to be devised in this field. This thesis aims to utilise the objective measurement of sleep-wake disturbances across the circadian, homeostatic and ultradian sleep systems in PD through four empiric experiments to help inform our understanding of these critical symptoms. While the usefulness of self-report data is not doubted as a means of engaging the patient and hearing their voice they cannot serve the same identification and measurement uses of objective data. Given our ageing population, the need for diagnostic, predictive and sensitive monitoring biomarkers in Parkinson’s disease has never been greater. Objective, accurate and reliable measurement techniques, as demonstrated in this thesis, underpins further research in this field

    Clinical and radiological studies in PSP and related conditions

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    This thesis examines clinical and radiological aspects of Progressive Supranuclear Palsy (PSP) and related conditions. Significant milestones occur sooner in pathologically confirmed PSP than multiple system atrophy (MSA); older age of onset and shorter duration to first milestone are associated with worse prognosis in both; in PSP, the Richardson’s syndrome phenotype and male gender and in MSA, early autonomic failure and the female gender are also predictive of poorer prognosis. Using objective measurements of bradykinesia we found progressive bradykinesia and hypokinesia in Parkinson’s disease (PD) which correlates with disability and responds to levodopa but hypokinesia without decrement in PSP. Using conventional MRI 72.7% of PSP and 76.9% of MSA are correctly identified. The ‘hummingbird sign’ was highly specific for PSP, but sensitvity was 68.4%. A simple measurement of the midbrain < 9.35mm had 100% specificity for a pathological diagnosis of PSP. In a clinically diagnosed PSP 90.5% had a measurement of < 9.35mm. Using high field 9.4 Tesla MRI, the anatomy of the subthalamic nucleus is clearly defined when compared to histology in post mortem material. The anteromedial portion was hypointense in correlation with Perls stain and there was variability in the volume, shape and location of its borders. The nigrosomes within the substantia nigra were visibile as high intensity bands which correlated with calbindin poor zones on immunohistochemical stains. The volume and anatomy were preserved in PD but not PSP. Multimodal 3 Telsla MRI during life revealed distinct patterns of atrophy in PSP and MSA using voxel-based morphometry. Tract-based spatial statistics revealed abnormalities in the frontal and parieto-occipital white matter changes in PSP more than MSA. Midbrain atrophy and frontal white matter increased mean diffusivity were associated with increasing PSP rating scale score, and frontal white matter reduced fractional anisotropy with disease duration

    Bradykinesia in non-parkinsonian conditions: the emerging concept of a network disorder

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    Bradykinesia (movement slowness) is one of the cardinal motor symptoms of Parkinson‟s disease and atypical parkinsonism and it has hystorically been interpreted as a motor disorder due to basal ganglia dysfunction. Clinical and experimental studies, however, indicate that it may be also observed in the context of various neurological conditions not primarily characterized by parkinsonism. These conditions include hyperkinetic movement disorders, such as dystonia and chorea, as well conditions primarily characterized by tremor (e.g. essential tremor) or other nervous diseases characterized by the involvement of brain areas and network including not only the basal ganglia but also the cerebellum and upper motoneurons. Also, movement slowness may be observed in patients with neurodegenerative or inflammatory diseases of the central nervous system of various origins, like dementia or multiple sclerosis. From a pathophysiological standpoint, the observation of movement slowness in neurological conditions not primarily characterized by parkinsonism is possibly explained by a brain network dysfunction, as hypothesized in parkinsonism. In the present thesis, we will first provide an updated overview on bradykinesia in non-parkinsonian conditions and discuss major findings of clinical reports and experimental studies. In the experimental part of the present thesis, we will provide the results from three original studies, which investigated the presence of bradykinesia and its possible pathophysiological mechanisms in (i) patients with essential tremor, (ii) patients with Alzheimer‟s disease, and (iii) patients with amyotrophic lateral sclerosis. Finally, we will provide a unifying pathophysiological interpretation of bradykinesia in non-parkinsonian conditions from a network perspective and emphasize possible terminological implications

    Do informal caregivers of people with dementia mirror the cognitive deficits of their demented patients?:A pilot study

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    Recent research suggests that informal caregivers of people with dementia (ICs) experience more cognitive deficits than noncaregivers. The reason for this is not yet clear. Objective: to test the hypothesis that ICs ‘mirror' the cognitive deficits of the demented people they care for. Participants and methods: 105 adult ICs were asked to complete three neuropsychological tests: letter fluency, category fluency, and the logical memory test from the WMS-III. The ICs were grouped according to the diagnosis of their demented patients. One-sample ttests were conducted to investigate if the standardized mean scores (t-scores) of the ICs were different from normative data. A Bonferroni correction was used to correct for multiple comparisons. Results: 82 ICs cared for people with Alzheimer's dementia and 23 ICs cared for people with vascular dementia. Mean letter fluency score of the ICs of people with Alzheimer's dementia was significantly lower than the normative mean letter fluency score, p = .002. The other tests yielded no significant results. Conclusion: our data shows that ICs of Alzheimer patients have cognitive deficits on the letter fluency test. This test primarily measures executive functioning and it has been found to be sensitive to mild cognitive impairment in recent research. Our data tentatively suggests that ICs who care for Alzheimer patients also show signs of cognitive impairment but that it is too early to tell if this is cause for concern or not
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