Connecting process models to response times through Bayesian hierarchical regression analysis.

Process models specify a series of mental operations necessary to complete a task. We demonstrate how to use process models to analyze response-time data and obtain parameter estimates that have a clear psychological interpretation. A prerequisite for our analysis is a process model that generates a count of elementary information processing steps (EIP steps) for each trial of an experiment. We can estimate the duration of an EIP step by assuming that every EIP step is of random duration, modeled as draws from a gamma distribution. A natural effect of summing several random EIP steps is that the expected spread of the overall response time increases with a higher EIP step count. With modern probabilistic programming tools, it becomes relatively easy to fit Bayesian hierarchical models to data and thus estimate the duration of a step for each individual participant. We present two examples in this paper: The first example is children's performance on simple addition tasks, where the response time is often well predicted by the smaller of the two addends. The second example is response times in a Sudoku task. Here, the process model contains some random decisions and the EIP step count thus becomes latent. We show how our EIP regression model can be extended to such a case. We believe this approach can be used to bridge the gap between classical cognitive modeling and statistical inference and will be easily applicable to many use cases.

Feasibility and impact of ketogenic dietary interventions in polycystic kidney disease: KETO-ADPKD-a randomized controlled trial.

Ketogenic dietary interventions (KDIs) are beneficial in animal models of autosomal-dominant polycystic kidney disease (ADPKD). KETO-ADPKD, an exploratory, randomized, controlled trial, is intended to provide clinical translation of these findings (NCT04680780). Sixty-six patients were randomized to a KDI arm (ketogenic diet [KD] or water fasting [WF]) or the control group. Both interventions induce significant ketogenesis on the basis of blood and breath acetone measurements. Ninety-five percent (KD) and 85% (WF) report the diet as feasible. KD leads to significant reductions in body fat and liver volume. Additionally, KD is associated with reduced kidney volume (not reaching statistical significance). Interestingly, the KD group exhibits improved kidney function at the end of treatment, while the control and WF groups show a progressive decline, as is typical in ADPKD. Safety-relevant events are largely mild, expected (initial flu-like symptoms associated with KD), and transient. Safety assessment is complemented by nuclear magnetic resonance (NMR) lipid profile analyses.

Increased Mortality Among Critically Injured Motorcyclists Over 65 Years of Age.

BACKGROUND: Motorcycle accidents account for a large fraction of the patients with polytrauma treated in German hospitals. Clinical experience indicates that an in- creasing number of older motorcyclists are having accidents. We studied whether such individuals are subject to higher mortality and longer hospital stays. METHODS: We retrospectively evaluated data from the Traumaregister DGU® (TR- DGU) concerning all patients (n = 13 850) who were registered in the TR-DGU as having sustained trauma in a motorcycle accident from 2002 to 2015 and who had an Injury Severity Score (ISS) greater than 8. The patients were divided into four age groups for further study. RESULTS: Despite a nearly identical severity of anatomical injury according to the ISS, persons sustaining trauma in motorcycle accidents who were over 65 years of age (n = 892) needed longer and more intensive treatment than their younger counter- parts. They were invasively ventilated for a longer time (+ 1.2 days), kept for a longer time on the intensive care unit (+ 1.7 days), and stayed in the hospital three days longer. These older persons injured in motorcycle accidents had a disproportionate mortality in comparison to other polytrauma patients and a significantly elevated mor- tality in comparison to their younger counterparts-15.8%, compared to 7.2% among patients aged 45 to 64. Older trauma patients are more likely than younger ones to develop lethal complications in the later course of their hospitalization, while younger trauma patients who die generally do so as a direct result of the traumatic injury. CONCLUSION: Patients over age 65 who sustain trauma in motorcycle accidents have a higher mortality, a longer duration of ventilation, and longer stays in the intensive care unit and in the hospital overall than their younger counterparts. These patients present a special challenge to the treating medical team.