Using virtual reality to explore the role of conflict resolution and environmental salience in Freezing of Gait in Parkinson's disease

BackgroundThe freezing phenomenon is among the most disabling symptoms of Parkinson's disease (PD) manifesting most commonly as Freezing of Gait with a paroxysmal cessation of effective stepping. Recent studies have suggested that freezing is related to both impairments in conflict resolution as well as the processing of environmentally salient information.MethodsIn this study, we utilized a virtual reality gait paradigm to investigate differences in motor outflow between PD patients with (n = 36) and without (n = 37) Freezing of Gait, as well as age-matched healthy controls (n = 18). Subjects were required to navigate a realistic on-screen environment with the use of foot pedals to simulate stepping whilst responding to either cues associated with conflict resolution (congruent ‘Red’, ‘Green’ or ‘Blue’) or environmental salience (wide, narrow and sliding doorways). Footstep latency was used as a measure of motor output.ResultsSignificantly increased stepping latencies were observed in freezers compared to non-freezers (p = 0.004) and controls (p = 0.016) in response to stimuli requiring the inhibition of implicitly cued behavior (‘red’ cue). Patients with Freezing of Gait also demonstrated increased motor latency compared to non-freezers and controls specifically in response to environmentally salient triggers including narrow doorways (p = 0.03 and 0.01 respectively) and the opening of a sliding door (p = 0.036 and 0.048 respectively). Performance on the paradigm in relation to these triggers correlated significantly with self-reported freezing severity.ConclusionThese results suggest that deficits in conflict resolution and visuospatial processing may reflect some of the neural mechanisms associated with freezing behavior and that these can be probed in a virtual reality environment.     

Pre-marital predictors of marital violence in the WHO World Mental Health (WMH) Surveys

Social Psychiatry and Psychiatric Epidemiology - Intimate partner violence (IPV) is a pervasive public health problem. Existing research has focused on reports from victims and few studies have...     

Suicidal Ideation in Bipolar Disorder: The Relation with Clinical and Sociodemographic Variables

Psychiatric Quarterly - Bipolar disorder (BD) has the highest risk of suicide among all mental disorders. Thus, identifying factors related to suicidal ideation is essential for a better assessment...     

The Impact of COVID-19 on Drug Use and Harm Reduction Programming in the Middle East and North Africa (MENA) Region: a Regional Consultation of Stakeholders and People Who Use Drugs

International Journal of Mental Health and Addiction - The Middle East and North Africa (MENA) region has witnessed a slow but steady increase in the harm reduction response since 2016. It is...     

Cohort profile: biological pathways of risk and resilience in Syrian refugee children (BIOPATH)

The BIOPATH cohort was established to explore the interplay of psychosocial and biological factors in the development of resilience and mental health problems in Syrian refugee children. Based in Lebanon, a middle-income country significantly impacted by the refugee crisis, it is the first such cohort of refugees in the Middle East. Families were recruited from informal tented settlements in the Beqaa region using purposive cluster sampling. At baseline (October 2017–January 2018), N = 3188 individuals participated [n = 1594 child–caregiver dyads; child gender, 52.6% female; mean (SD) age = 11.44 (2.44) years, range = 6–19]. Re-participation rate at 1-year follow-up was 62.8%. Individual interviews were conducted with children and primary caregivers and biological samples collected from children. Measures include: (1) children’s well-being and mental health problems (using tools validated against clinical interviews in a subsample of the cohort); (2) psychosocial risk and protective factors at the level of the individual (e.g. coping strategies), family (e.g. parent–child relationship), community (e.g. collective efficacy), and wider context (e.g. services); (3) saliva samples for genetic and epigenetic (methylation) analyses; (4) hair samples to measure cortisol, dehydroepiandrosterone (DHEA) and testosterone. This cohort profile provides details about sampling and recruitment, data collection and measures, demographic data, attrition and potential bias, key findings on resilience and mental health problems in children and strengths and limitations of the cohort. Researchers interested in accessing data should contact Professor Michael Pluess at Queen Mary University of London, UK (e-mail: m.pluess@qmul.ac.uk).

     

An analytical model applied to a multicenter pneumococcal enzyme-linked immunosorbent assay study

Pneumococcal conjugate vaccines will eventually be licensed after favorable results from phase III efficacy trials. After licensure of a conjugate vaccine for invasive pneumococcal disease in infants, new conjugate vaccines will likely be licensed primarily on the basis of immunogenicity data rather than clinical efficacy. Analytical methods must therefore be developed, evaluated, and validated to compare immunogenicity results accurately within and between laboratories for different vaccines. At present no analytical technique is uniformly accepted and used in vaccine evaluation studies to determine the acceptable level of agreement between a laboratory result and the assigned value for a given serum sample. This multicenter study describes the magnitude of agreement among 12 laboratories quantifying an identical series of 48 pneumococcal serum specimens from 24 individuals (quality-control sera) by a consensus immunoglobulin G (IgG) enzyme-linked immunosorbent assay (ELISA) developed for this study. After provisional or trial antibody concentrations were assigned to the quality-control serum samples for this study, four methods for comparison of a series of laboratory-determined values with the assigned concentrations were evaluated. The percent error between assigned values and laboratory-determined concentrations proved to be the most informative of the four methods. We present guidelines that a laboratory may follow to analyze a series of quality-control sera to determine if it can reproduce the assigned antibody concentrations within an acceptable level of tolerance. While this study focused on a pneumococcal IgG ELISA, the methods that we describe are easily generalizable to other immunological assays.     

Left temporal impairment of auditory information processing in prematurely born 9-year-old children: an electrophysiological study.

Children born preterm more than average display cognitive difficulties that are significant enough to prevent normal schooling. The aim of our study was to provide better understanding of the long-term neuropathological processes associated with preterm injury, through the hypothesis that mild cognitive disorders might be related to slight deficits in primary functions such as attention and perception. Assessment of auditory pre-attentive processes was performed by recording the obligatory sensory response (N250) and the change-detection response (Mismatch Negativity, MMN). Topographic study of these responses was performed in fifteen 9-year-old children born preterm (27-33 weeks gestational age) matched to fifteen control children born at term. The auditory stimulus sequence consisted of 1000 Hz standard and 1100 Hz deviant tones (15%) delivered binaurally with an interstimulus interval of 700 ms. The results showed that MMN was similar in both groups. Analysis of the responses to standard repetitive tones demonstrated significantly smaller N250 wave amplitude in children born preterm. Scalp current density maps showed that this reduction in amplitude was associated with lower activity of both frontal and left supratemporal generators. Although the functional significance of the N250 wave in children remains to be clarified, our results indicate a disorder of auditory processes related to prematurity that might have consequences on the development of higher-level processes.