Parkinson’s disease with concomitant generalized anxiety disorder – case report

Parkinson’s diseases, occuring most often between the ages of 50 and 60 years, on average at the age 58 years is a progressive degenerative disease of the central nervous system of global importance and serious consequences for public health. Its main symptoms are tremor at rest muscle stiffness and bradykinesia, i.e. slowness of movement (the so-called parkinsonian triad). Atrophic lessons of substantia nigra, located in the midbrain, responsible for the production of dopamine, contribute to the onset of symptoms of the disease. Patients with Parkinson’s diseases suffer from a variety of extra-motor symptoms often psychiatric disorders, especially panic or generalized anxiety. The author presents the case of 63 years old man diagnosed with Parkinson’s diseases 4 years ago, with quite a significant severity in the last 2 years. Left limb weakness (upper and lower) deepened and general slowing of movement developed then restless legs syndrome developed fully (specific sensations in the area of the feet and lower legs in the evening and night hours, temporarily decreasing when moving, walking, stretching the muscles). For about 6 months he have had attacks of anxiety and anxiety as well as a fully developed generalized anxiety disorder. The combination of levodopa and carbidopa and pregabalin was used, resulting in a reduction of slowness and stiffness as well as a significant reduction in anxiety and anxiety after approximately 8 weeks.

Aging Increases Cross-Modal Distraction by Unexpected Sounds: Controlling for Response Speed

It is well-established that task-irrelevant sounds deviating from an otherwise predictable auditory sequence capture attention and disrupt ongoing performance by delaying responses in the ongoing task. In visual tasks, larger distraction by unexpected sounds (deviance distraction) has been reported in older than in young adults. However, past studies based this conclusion on the comparisons of absolute response times (RT) and did not control for the general slowing typically observed in older adults. Hence, it remains unclear whether this difference in deviance distraction between the two age groups reflects a genuine effect of aging or a proportional effect of similar size in both groups. We addressed this issue by using a proportional measure of distraction (PMD) to reanalyze the data from four past studies and used Bayesian estimation to generate credible estimates of the age-related difference in deviance distraction and its effect size. The results were unambiguous: older adults exhibited greater deviance distraction than young adults when controlling for baseline response speed (in each individual study and in the combined data set). Bayesian estimation revealed a proportional lengthening of RT by unexpected sounds that was about twice as large in older than in young adults (corresponding to a large statistical effect size). A similar analysis was carried out on the proportion of correct responses (PC) and produced converging results. Finally, an additional Bayesian analysis comparing data from cross-modal and uni-modal studies confirmed the selective effect of aging on distraction in the first and not the second. Overall, our study shows that older adults performing a visual categorization task do exhibit greater distraction by unexpected sounds than young adults and that this effect is not explicable by age-related general slowing.

The temporal dynamics of the Stroop effect from childhood to young and older adulthood

It is well admitted that children and older adults tend to show longer response latencies at the Stroop task than young adults. The present study aims at clarifying the rational of such changes from childhood to adulthood and in ageing by comparing the impacted cognitive processes across age groups. More precisely, the aim was to clarify if all processes take more time to be executed, hence implying that longer latencies rely mainly on processing speed or if an additional process lengthens the resolution of the conflict in children and/or older adults. To this aim we recorded brain electrical activity using EEG in school-age children, young and older adults while they performed a classic verbal Stroop task. To decompose the signal in the underlying brain networks, we used microstates analyses and compared congruent, incongruent and neutral trials across the three age-groups. Behaviorally, children and older adults presented longer latencies and larger Stroop effects relative to young adults. The microstates results showed that children tend to present different brain configurations compared to both adult groups, even though some brain configurations remained identical among the three groups. In particular, additional brain networks were involved in children to perform the Stroop task, which party account for the longer latencies in this group. By contrast, in aging the results favor the general slowing hypothesis rather than a decline in a specific process since all involved brain networks were similar in the two adult groups but slowed down in the older one.

Altered phase and nonphase EEG activity expose impaired maintenance of a spatial-object attentional focus in multiple sclerosis patients

Some of the anatomical and functional basis of cognitive impairment in multiple sclerosis (MS) currently remains unknown. In particular, there is scarce knowledge about modulations in induced EEG (nonphase activity) for diverse frequency bands related to attentional deficits in this pathology. The present study analyzes phase and nonphase alpha and gamma modulations in 26 remitting-relapsing multiple sclerosis patients during their participation in the attention network test compared with twenty-six healthy controls (HCs) matched in sociodemographic variables. Behavioral results showed that the MS group exhibited general slowing, suggesting impairment in alerting and orienting networks, as has been previously described in other studies. Time–frequency analysis of EEG revealed that the gamma band was related to the spatial translation of the attentional focus, and the alpha band seemed to be related to the expectancy mechanisms and cognitive processing of the target. Moreover, phase and nonphase modulations differed in their psychophysiological roles and were affected differently in the MS and HC groups. In summary, nonphase modulations can unveil hidden cognitive mechanisms for phase analysis and complete our knowledge of the neural basis of cognitive impairment in multiple sclerosis pathology.

Utilizing Agent-Based Modeling to Evaluate Operational Impacts of an Incident and Possible Alternatives on U.S. Waterways

Operations along inland waterways are particularly vulnerable to severe weather events which can create adverse conditions for towboat operators to manage, resulting in increased risk of accidents. However, it is challenging to know or understand the extent to which new regulations or policies on tow operating procedures may reduce impacts from a given scenario. An agent-based model (ABM) representing actual river operating procedures was developed previously to evaluate emergent characteristics and system-wide impacts arising from the interactions between disruptions, towboat operator responses, and regulations. In this work, we validate the effectiveness of the ABM model for improved decision support by comparing it with observed waterway traffic as captured by Automatic Identification System (AIS) data, then apply the model to a case study based on a 2005 incident on the Ohio River. A series of counterfactual scenarios are simulated to better understand potential impacts of the incident on waterway system performance and potential alternative outcomes given different operational responses and regulations. The analysis indicates that imposing tow movement restrictions, such as waiting for a helper towboat, under adverse river conditions can result in a general slowing of the system but with potentially lesser impacts than what would be caused if the system operates as normal and results in an incident that lasts multiple days. The analysis also indicates that the waterway system can return to normal operations within a matter of weeks.

New insights into the cognitive effects of sleep deprivation by decomposition of a cognitive throughput task

Study Objectives A cognitive throughput task known as the Digit Symbol Substitution Test (DSST) (or Symbol Digit Modalities Test) has been used as an assay of general cognitive slowing during sleep deprivation. Here, the effects of total sleep deprivation (TSD) on specific cognitive processes involved in DSST performance, including visual search, spatial memory, paired-associate learning, and motor response, were investigated through targeted task manipulations. Methods A total of 12 DSST variants, designed to manipulate the use of specific cognitive processes, were implemented in two laboratory-based TSD studies with N = 59 and N = 26 subjects, respectively. In each study, the Psychomotor Vigilance Test (PVT) was administered alongside the DSST variants. Results TSD reduced cognitive throughput on all DSST variants, with response time distributions exhibiting rightward skewing. All DSST variants showed practice effects, which were however minimized by inclusion of a pause between trials. Importantly, TSD-induced impairment on the DSST variants was not uniform, with a principal component analysis revealing three factors. Diffusion model decomposition of cognitive processes revealed that inter-individual differences during TSD on a two-alternative forced choice DSST variant were different from those on the PVT. Conclusions While reduced cognitive throughput has been interpreted to reflect general cognitive slowing, such TSD-induced impairment appears to reflect cognitive instability, like on the PVT, rather than general slowing. Further, comparisons between task variants revealed not one, but three distinct underlying processes impacted by sleep deprivation. Moreover, the practice effect on the task was found to be independent of the TSD effect and minimized by a task pacing manipulation.

Age-related alterations in inhibitory control investigated using the minimally delayed oculomotor response task

Healthy, older adults are widely reported to experience cognitive decline, including impairments in inhibitory control. However, this general proposition has recently come under scrutiny because ageing effects are highly variable between individuals, are task dependent, and are sometimes not distinguished from general age-related slowing. We recently developed the minimally delayed oculomotor response (MDOR) task in which participants are presented with a simple visual target step, and instructed to saccade not to the target when it appears (a prosaccade response), but when it disappears (i.e. on target offset). Varying the target display duration (TDD) prevents offset timing being predictable from the time of target onset, and saccades prior to the offset are counted as errors. A comparison of MDOR task performance in a group of 22 older adults (mean age 62 years, range 50–72 years) with that in a group of 39 younger adults (22 years, range 19–27 years) demonstrated that MDOR latency was significantly increased in the older group by 34–68 ms depending on TDD. However, when MDOR latencies were corrected by subtracting the latency observed in a standard prosaccade task, the latency difference between groups was abolished. There was a larger latency modulation with TDD in the older group which was observed even when their generally longer latencies were taken into account. Error rates were significantly increased in the older group. An analysis of the timing distribution of errors demonstrated that most errors were failures to inhibit responses to target onsets. When error distributions were used to isolate clear inhibition failures from other types of error, the older group still exhibited significantly higher error rates as well as a higher residual error rate. Although MDOR latency in older participants may largely reflect a general slowing in the oculomotor system with age, both the latency modulation and error rate results are consistent with an age-related inhibitory control deficit. How this relates to performance on other inhibitory control tasks remains to be investigated.

Left-Ventricular Pressure Relaxation and Diastolic Function of Isolated Working Mammalian Hearts at Hypothermia

Background: Hypothermia is well known to elevate the time constant (whatever model is used) of the isochoric left-ventricular pressure fall. Due to different critera in use, it remained unclear whether prolonged diastole in hypothermia is sufficient for complete relaxation. Detecting and quantifying incomplete relaxation may become a valuable tool to prevent diastolic heart failure in hypothermia.Methods: Left-ventricular pressure decays in isolated guinea pig and rat hearts are analysed by 4-parametric regression at different temperatures, at sinus rhythm and electrical stimulation. Residual contraction (F_RC) is introduced and quantified by extrapolating the model's pressure forecast to end-systole, subtracting the asymptote, and normalising.Resultts: Isochoric pressure decay fits the regression model at all temperatures and heart beat frequencies. Residual contraction is virtually absent at normothermia and remains very small (F_RC<3%) down to 31°C. Lower temperatures or pacing induces higher F_RC. Eventually, the pressure curve becomes considerably elevated and looses its concavity.Conclusions: Despite slower pressure fall, ventricular relaxation remains fairly complete at hypothermia; and depends on considerable autoregulation of the individual heart. It is concluded (not proved) that individual emergence of negative lusitropy may indicate imminent heart failure. Asymptotic pressure rises are interpreted at higher ventricular tonus, independent from velocity of relaxation. Gradual increasing time constants may be attributed to a general slowing of bioreactions as temperature falls. Remarkable curve shape changes may be caused by aftercontractions due to elevated Ca++ sensitivity at hypothermia and high Ca++ load by pacing.

The climate effects of increasing ocean albedo: An idealized representation of solar geoengineering

Marine cloud brightening has been proposed as a means of geoengineering/climate intervention, or deliberately altering the climate system to offset anthropogenic climate change. As an idealized representation of marine cloud brightening, this paper discusses experiment G1ocean-albedo of the Geoengineering Model Intercomparison Project (GeoMIP), involving an abrupt quadrupling of the CO2 concentration and an instantaneous increase in ocean albedo to maintain approximate net top-of-atmosphere radiative flux balance. Eleven Earth System Models are relatively consistent in their temperature, radiative flux, and hydrological cycle responses to this experiment. Due to the imposed forcing, air over the land surface warms by a model average of 1.14 K, while air over most of the ocean cools. Some parts of the near-surface air temperature over ocean warm due to heat transport from land to ocean. These changes generally resolve within a few years, indicating that changes in ocean heat content play at most a small role in the warming over the oceans. The hydrological cycle response is a general slowing down, with high heterogeneity in the response, particularly in the tropics. While idealized, these results have important implications for marine cloud brightening, or other methods of geoengineering involving spatially heterogeneous forcing, or other general forcings with a strong land/ocean contrast. It also reinforces previous findings that keeping top-of-atmosphere net radiative flux constant is not sufficient for preventing changes in global mean temperature.