Quantification and recognition of parkinsonian gait from monocular video imaging using kernel-based principal component analysis

<p>Abstract</p> <p>Background</p> <p>The computer-aided identification of specific gait patterns is an important issue in the assessment of Parkinson's disease (PD). In this study, a computer vision-based gait analysis approach is developed to assist the clinical assessments of PD with kernel-based principal component analysis (KPCA).</p> <p>Method</p> <p>Twelve PD patients and twelve healthy adults with no neurological history or motor disorders within the past six months were recruited and separated according to their "Non-PD", "Drug-On", and "Drug-Off" states. The participants were asked to wear light-colored clothing and perform three walking trials through a corridor decorated with a navy curtain at their natural pace. The participants' gait performance during the steady-state walking period was captured by a digital camera for gait analysis. The collected walking image frames were then transformed into binary silhouettes for noise reduction and compression. Using the developed KPCA-based method, the features within the binary silhouettes can be extracted to quantitatively determine the gait cycle time, stride length, walking velocity, and cadence.</p> <p>Results and Discussion</p> <p>The KPCA-based method uses a feature-extraction approach, which was verified to be more effective than traditional image area and principal component analysis (PCA) approaches in classifying "Non-PD" controls and "Drug-Off/On" PD patients. Encouragingly, this method has a high accuracy rate, 80.51%, for recognizing different gaits. Quantitative gait parameters are obtained, and the power spectrums of the patients' gaits are analyzed. We show that that the slow and irregular actions of PD patients during walking tend to transfer some of the power from the main lobe frequency to a lower frequency band. Our results indicate the feasibility of using gait performance to evaluate the motor function of patients with PD.</p> <p>Conclusion</p> <p>This KPCA-based method requires only a digital camera and a decorated corridor setup. The ease of use and installation of the current method provides clinicians and researchers a low cost solution to monitor the progression of and the treatment to PD. In summary, the proposed method provides an alternative to perform gait analysis for patients with PD.</p

An Examination of the Psychopathy Checklist: Youth Version (PCL:YV) Among Male Adolescent Offenders: An Item Response Theory Analysis

This study examined the applicability of the Psychopathy Checklist: Youth Version (PCL:YV; Forth, Kosson, & Hare, 2003) among a large sample of serious offending adolescent males. Adopting an item response theory approach, item properties of the PCL:YV were examined using the generalized partial credit model. Results showed that need for stimulation, "irresponsibility," and callous & unemotional were sensitive to changes in respondents' varying psychopathy levels, whereas lack of realistic, long-term goals; superficial charm; and revocation of conditional release were less so (quoted PCL:YV item published with permission by Multi-Health Systems, Inc.; see full permissions statement in footnote 1 in the article; other items are paraphrased). Substantial differential item functioning was also found in 15 of the 20 PCL:YV items among Caucasian, African American, and Hispanic offending boys, indicating that item functioning was not invariant across race/ethnicity. Questions remain regarding whether the construct of psychopathy as assessed with the PCL:YV is equivalent across adolescents in general and across different race/ethnic groups in particular

Guidelines for developing, translating, and validating a questionnaire in perioperative and pain medicine

The task of developing a new questionnaire or translating an existing questionnaire into a different language might be overwhelming. The greatest challenge perhaps is to come up with a questionnaire that is psychometrically sound, and is efficient and effective for use in research and clinical settings. This article provides guidelines for the development and translation of questionnaires for application in medical fields, with a special emphasis on perioperative and pain medicine. We provide a framework to guide researchers through the various stages of questionnaire development and translation. To ensure that the questionnaires are psychometrically sound, we present a number of statistical methods to assess the reliability and validity of the questionnaires

Differential models of twin correlations in skew for body-mass index (BMI).

BACKGROUND:Body Mass Index (BMI), like most human phenotypes, is substantially heritable. However, BMI is not normally distributed; the skew appears to be structural, and increases as a function of age. Moreover, twin correlations for BMI commonly violate the assumptions of the most common variety of the classical twin model, with the MZ twin correlation greater than twice the DZ correlation. This study aimed to decompose twin correlations for BMI using more general skew-t distributions. METHODS:Same sex MZ and DZ twin pairs (N = 7,086) from the community-based Washington State Twin Registry were included. We used latent profile analysis (LPA) to decompose twin correlations for BMI into multiple mixture distributions. LPA was performed using the default normal mixture distribution and the skew-t mixture distribution. Similar analyses were performed for height as a comparison. Our analyses are then replicated in an independent dataset. RESULTS:A two-class solution under the skew-t mixture distribution fits the BMI distribution for both genders. The first class consists of a relatively normally distributed, highly heritable BMI with a mean in the normal range. The second class is a positively skewed BMI in the overweight and obese range, with lower twin correlations. In contrast, height is normally distributed, highly heritable, and is well-fit by a single latent class. Results in the replication dataset were highly similar. CONCLUSIONS:Our findings suggest that two distinct processes underlie the skew of the BMI distribution. The contrast between height and weight is in accord with subjective psychological experience: both are under obvious genetic influence, but BMI is also subject to behavioral control, whereas height is not

Perceived change in physical activity levels and mental health during COVID-19: Findings among adult twin pairs

BACKGROUND: Physical distancing and other COVID-19 pandemic mitigation strategies may have unintended consequences on a number of health behaviors and health outcomes. The purpose of this study was to investigate the association between perceived change in physical activity or exercise and mental health outcomes over the short-term in response to COVID-19 mitigation strategies in a sample of adult twins. METHODS: This was a cross-sectional study of 3,971 identical and same-sex fraternal adult twins (909 pairs, 77% identical) from the community-based Washington State Twin Registry. Participants in this study completed an online survey examining the impact of COVID-19 mitigation on a number of health-related behaviors and outcomes, administered between March 26 and April 5, 2020. In the present study, the exposure was perceived change in physical activity or exercise. The outcomes were levels of perceived anxiety and stress. RESULTS: More twin pairs reported a decrease in physical activity levels (42%) than those reporting no change (31%) or increased physical activity levels (27%). A perceived decrease in physical activity or exercise was associated with higher stress and anxiety levels. However, the physical activity–stress relationship was confounded by genetic and shared environmental factors. On the other hand, the physical activity–anxiety relationship held after controlling for genetic and shared environmental factors, although it was no longer significant after further controlling for age and sex, with older twins more likely to report lower levels of anxiety and females more likely to report higher levels of anxiety. CONCLUSIONS: Strategies to mitigate the COVID-19 pandemic may be impacting physical activity and mental health, with those experiencing a decrease in physical activity also having higher levels of stress and anxiety. These relationships are confounded by genetic and shared environmental factors, in the case of stress, and age and sex, in the case of anxiety

Cross-sectional association between soda consumption and body mass index in a community-based sample of twins

Background: Consumption of sugar-sweetened beverages, such as soda, have been shown to play an important role in weight gain. Although soda consumption has been associated with body mass index (BMI) in many studies, it has been difficult to ascertain a true causal relationship between soda consumption and BMI for two reasons. First, findings have been based largely on observational and cross-sectional studies, with much less evidence from randomized controlled trials. Second, the reported relationships may be confounded by genetic and shared environmental factors that affect both soda consumption and BMI. In the present study, we used the twin design to better understand the relationship between soda consumption and BMI by accounting for measured and unmeasured confounds in non-experimental data. Associations from genetically informed tests in twins are considered “quasi-causal,” suggesting that our confidence in the causal underpinning of the association between soda consumption and BMI has been strengthened. We hypothesized that the association between soda consumption and BMI would be significant both between and within twins. Methods: This was a cross sectional study of 5787 same sex adult twin pairs (18–97 years, 66% female) from the community based Washington State Twin Registry. Structural equation modeling (SEM) was employed to investigate associations between soda consumption and BMI in the population (the phenotypic association between exposure and outcome among all twins treated as individuals) and within pairs of identical and fraternal twins (the quasi-causal association controlling for between pair genetic and environmental confounds). Results: Among all twins, there was a significant phenotypic association between soda consumption and BMI that held when controlling for age, sex, race, annual household income, and education level (P < 0.05). In the quasi-causal model, however, the effect of soda consumption on BMI was greatly reduced and no longer significant, with a large genetic confound in both men and women (P < 0.05). Conclusion: Among a large group of adult twin pairs, increased soda consumption was associated with increased BMI; however, the observed association was mediated by a genetic background common to both

Descriptive statistics of body-mass index (BMI).

<p>Descriptive statistics of body-mass index (BMI).</p

Distribution of BMI by gender.

<p>Distribution of BMI by gender.</p

Distribution of height (in feet) between twin pairs by gender and zygosity.

<p>Distribution of height (in feet) between twin pairs by gender and zygosity.</p