Relapse patterns of two-jaw surgical correction in patients with skeletal Class III malocclusion and different vertical facial types.

The aim of this study was to evaluate postoperative relapse after the surgical correction of skeletal Class III deformities of various facial patterns as a guide to surgical planning. A retrospective cohort study of 90 consecutive patients with skeletal Class III malocclusion who underwent bimaxillary surgery was performed. The surgical outcomes and postoperative stability were compared. The primary predictor variable was vertical facial type, which was classified into three groups according to the Frankfort mandibular plane angle (FMA). The primary outcome of angular and linear measurements was obtained using serial cone beam computed tomography scans obtained at time points of preoperative, 1 week after surgery, and orthodontic debonding. No significant difference in skeletal relapse was observed in patients with the different vertical facial types. The mandible displayed a forward and upward relapse in all three groups postoperatively. The patients with a low FMA exhibited a more consistent mandibular relapse pattern than those with a normal or high FMA. These findings suggest that bimaxillary surgery is clinically stable for mandibular prognathism regardless of the vertical facial pattern. However, 1-1.5 mm of overcorrection in the mandible setback should be considered in patients with a low FMA, because of the greater facial depth and consistent forward and upward mandibular relapse pattern.

Variations in the Course of the Carotid Arteries in Patients with Retropharyngeal Parathyroid Adenomas.

The carotid arteries, classically described as taking a relatively straight course through the neck, deviate medially in a minority of patients. At the extreme, the internal carotid arteries may "kiss" in the midline, coming extremely close to the pharyngeal wall. In this clinical report, we describe 5 patients with primary hyperparathyroidism, all with ectopic retropharyngeal parathyroid adenomas but all with varying carotid artery anatomy. We describe these variations using a previously developed clinical grading system that highlights 1) the relationship between carotid artery location and risk of injury during pharyngeal procedures and 2) the importance of universal, objective criteria to classify carotid anatomy. Radiologists should be familiar with variations in carotid anatomy and communicate them to the operative team.

A randomized trial of the electronic Lung Cancer Symptom Scale for quality-of-life assessment in patients with advanced non-small-cell lung cancer.

Introduction: Improving health-related quality of life (hrqol) is a key goal of systemic therapy in advanced lung cancer, although routine assessment remains challenging. We analyzed the impact of a real-time electronic hrqol tool, the electronic Lung Cancer Symptom Scale (elcss-ql), on palliative care (pc) referral rates, patterns of chemotherapy treatment, and use of other supportive interventions in patients with advanced non-small-cell lung cancer (nsclc) receiving first-line chemotherapy. Methods: Patients with advanced nsclc starting first-line chemotherapy were randomized to their oncologist receiving or not receiving their elcss-ql data before each clinic visit. Patients completed the elcss-ql at baseline, before each chemotherapy cycle, and at subsequent follow-up visits until disease progression. Prospective data about the pc referral rate, hrqol, and use of other supportive interventions were collected. Results: For the 95 patients with advanced nsclc who participated, oncologists received real-time elcss-ql data for 44 (elcss-ql arm) and standard clinical assessment alone for 51 (standard arm). The primary endpoint, the pc referral rate, was numerically higher, but statistically similar, for patients in the elcss-ql and standard arms. The hrqol scores over time were not significantly different between the two study arms. Conclusions: The elcss-ql is feasible as a tool for use in routine clinical practice, although no statistically significant effect of its use was demonstrated in our study. Improving access to supportive care through the collection of patient-reported outcomes and hrqol should be an important component of care for patients with advanced lung cancer.

Cognition and cerebrovascular function in primary hyperparathyroidism before and after parathyroidectomy.

PURPOSE: There are cognitive changes in primary hyperparathyroidism (PHPT) that improve with parathyroidectomy, but the mechanism of cognitive dysfunction has not been delineated. We assessed if cerebrovascular function is impaired in PHPT, improves post-parathyroidectomy and is associated with PTH level and cognitive dysfunction. METHODS: This is an observational study of 43 patients with mild hypercalcemic or normocalcemic PHPT or goiter. At baseline, cerebrovascular function (dynamic cerebral autoregulation and vasomotor reactivity) by transcranial Doppler and neuropsychological function were compared between all three groups. A subset underwent parathyroidectomy or thyroidectomy, and was compared 6 months post-operatively. RESULTS: Mean cerebrovascular and neuropsychological function was normal and no worse in PHPT compared to controls preoperatively. Higher PTH was associated with worse intracerebral autoregulation (r = - 0.43, p = 0.02) and worse cognitive performance on some tests. Post-parathyroidectomy, mood improved significantly, but changes did not differ compared to those having thyroidectomy (p = 0.84). There was no consistent improvement in cognition or change in vascular function in either surgical group. CONCLUSIONS: Although higher PTH was associated with worse intracerebral autoregulation, cerebrovascular function, cognition and mood were normal in mild PHPT. PTX did not improve vascular or cognitive function. The observed improvement in mood cannot be clearly attributed to PTX. Notwithstanding the small sample size, the results do not support changing current criteria for parathyroidectomy to include cognitive complaints. However, the associations between PTH, cognition and cerebral autoregulation merit future studies in those with more severe hyperparathyroidism.

Spin-charge-lattice coupling in YBaCuFeO5: Optical properties and first-principles calculations.

We combined spectroscopic ellipsometry, Raman scattering spectroscopy, and first-principles calculations to explore the optical properties of YBaCuFeO5 single crystals. Measuring the optical absorption spectrum of YBaCuFeO5 at room temperature revealed a direct optical band gap at approximately 1.41 eV and five bands near 1.69, 2.47, 3.16, 4.26, and 5.54 eV. Based on first-principles calculations, the observed optical excitations were appropriately assigned. Analysis of the temperature dependence of the band gap indicated anomalies in antiferromagnetic phase transition at 455 and 175 K. Additionally, a hardening in the frequency of the Eg phonon mode was observed at 175 K. The value of the spin-phonon coupling constant was 15.7 mRy/Å2. These results suggest a complex nature of spin-charge-lattice interactions in YBaCuFeO5.

Combined cancer patient-reported symptom and health utility tool for routine clinical implementation: a real-world comparison of the ESAS and EQ-5D in multiple cancer sites.

Background: We assessed whether the presence and severity of common cancer symptoms are associated with the health utility score (hus) generated from the EQ-5D (EuroQol Research Foundation, Rotterdam, Netherlands) in patients with cancer and evaluated whether it is possible pragmatically to integrate routine hus and symptom evaluation in our cancer population. Methods: Adult outpatients at Princess Margaret Cancer Centre with any cancer were surveyed cross-sectionally using the Edmonton Symptom Assessment System (esas) and the EQ-5D-3L, and results were compared using Spearman correlation coefficients and regression analyses. Results: Of 764 patients analyzed, 27% had incurable disease. We observed mild-to-moderate correlations between each esas symptom score and the hus (Spearman coefficients: -0.204 to -0.416; p < 0.0001 for each comparison), with the strongest associations being those for pain (R = -0.416), tiredness (R = -0.387), and depression (R =-0.354). Multivariable analyses identified pain and depression as highly associated (both p < 0.0001) and tiredness as associated (p = 0.03) with the hus. The ability of the esas to predict the hus was low, at 0.25. However, by mapping esas pain, anxiety, and depression scores to the corresponding EQ-5D questions, we could derive the hus using partial esas data, with Spearman correlations of 0.83-0.91 in comparisons with direct EQ-5D measurement of the hus. Conclusions: The hus derived from the EQ-5D-3L is associated with all major cancer symptoms as captured by the esas. The esas scores alone could not predict EQ-5D scores with high accuracy. However, esas-derived questions assessing the same domains as the EQ-5D-3L questions could be mapped to their corresponding EQ-5D questions to generate the hus, with high correlation to the directly measured hus. That finding suggests a potential approach to integrating routine symptom and hus evaluations after confirmatory studies.

Minimally-invasive approach to posterior fossa decompression: Initial experience in Adult Chiari Type 1 Malformation patients.

We report our initial experience using Minimally-Invasive Surgery (MIS) technique for Posterior Fossa Decompression (PFD) in Adult Chiari 1 Malformation (C1M) patients. Five subjects who were treated with MIS PFD at our center and followed up over a 5-year period. Another nine subjects who were treated with Open PFD and follow up over the same period were used for comparison. This study suggests that there are little differences in efficacy and safety between MIS and Open PFD. Larger series and prospective randomized trials comparing the two methods would provide higher-quality evidence and clarify the role of either technique in the treatment of C1M.

Gout as a risk factor for osteoporosis: epidemiologic evidence from a population-based longitudinal study involving 108,060 individuals.

Is gout a risk factor for future osteoporosis? This large population-based study comprising two matched groups of individuals with and without gout demonstrates that patients with gout have a 20% increase in the risk of developing osteoporosis in future through an 8-year follow-up. INTRODUCTION: To examine if gout is associated with an increased risk of osteoporosis. METHODS: We conducted a nationwide population-based retrospective matched-cohort study. Two matched cohorts (n = 36,458 with gout and 71,602 without gout) assembled and recruited from the Longitudinal Health Insurance Dataset containing 1 million subjects. Exclusion criteria were missing data, age < 20 years, short follow-up period, and pre-existing osteoporosis. Both cohorts were followed up until incident osteoporosis, death, or the end of the study. Person-year data and incidence rates were evaluated. A multivariable Cox model was used to derive an adjusted hazard ratio (aHR) after controlling for socioeconomic proxy, geographical difference, glucocorticoid and allopurinol exposure, various prespecified medical conditions, and comorbidities. RESULTS: Men comprised 72.8% of the cohorts. With a follow-up of 183,729 and 359,900 person-years for the gout and non-gout cohorts, 517 and 811 incidents of osteoporosis occurred, respectively, after excluding osteoporosis incidents in the first 3 years of follow-up. The cumulative incidence of osteoporosis was statistically higher in the gout cohort than in the non-gout cohort, at 3.3 versus 2.1% (P = 0.0036, log-rank). Our Cox model showed a 1.2-fold increase in the incidence of osteoporosis in the gout cohort, with an aHR of 1.2 (95% confidence interval, 1.06-1.35). CONCLUSIONS: This first population-based epidemiologic study supports the hypothesis that compared with individuals without gout; those with gout have a modest increase in the risk of developing osteoporosis in future.

Predicting primary outcomes of brain tumor patients with advanced neuroimaging MRI measures.

BACKGROUND: Advanced neuroimaging measures along with clinical variables acquired during standard imaging protocols provide a rich source of information for brain tumor patient treatment and management. Machine learning analysis has had much recent success in neuroimaging applications for normal and patient populations and has potential, specifically for brain tumor patient outcome prediction. The purpose of this work was to construct, using the current patient population distribution, a high accuracy predictor for brain tumor patient outcomes of mortality and morbidity (i.e., transient and persistent language and motor deficits). The clinical value offered is a statistical tool to help guide treatment and planning as well as an investigation of the influential factors of the disease process. METHODS: Resting state fMRI, diffusion tensor imaging, and task fMRI data in combination with clinical and demographic variables were used to represent the tumor patient population (n = 62; mean age = 51.2 yrs.) in a machine learning analysis in order to predict outcomes. RESULTS: A support vector machine classifier with a t-test filter and recursive feature elimination predicted patient mortality (18-month interval) with 80.7% accuracy, language deficits (transient) with 74.2%, motor deficits with 71.0%, language outcomes (persistent) with 80.7% and motor outcomes with 83.9%. The most influential features of the predictors were resting fMRI connectivity, and fractional anisotropy and mean diffusivity measures in the internal capsule, brain stem and superior and inferior longitudinal fasciculi. CONCLUSIONS: This study showed that advanced neuroimaging data with machine learning methods can potentially predict patient outcomes and reveal influential factors driving the predictions.

Fracture liaison services for osteoporosis in the Asia-Pacific region: current unmet needs and systematic literature review.

The analysis aimed to identify the treatment gaps in current fracture liaison services (FLS) and to provide recommendations for best practice establishment of future FLS across the Asia-Pacific region. The findings emphasize the unmet need for the implementation of new programs and provide recommendations for the refinement of existing ones. The study's objectives were to evaluate fracture liaison service (FLS) programs in the Asia-Pacific region and provide recommendations for establishment of future FLS programs. A systematic literature review (SLR) of Medline, PubMed, EMBASE, and Cochrane Library (2000-2017 inclusive) was performed using the following keywords: osteoporosis, fractures, liaison, and service. Inclusion criteria included the following: patients ≥ 50 years with osteoporosis-related fractures; randomized controlled trials or observational studies with control groups (prospective or retrospective), pre-post, cross-sectional and economic evaluation studies. Success of direct or indirect interventions was assessed based on patients' understanding of risk, bone mineral density assessment, calcium intake, osteoporosis treatment, re-fracture rates, adherence, and mortality, in addition to cost-effectiveness. Overall, 5663 unique citations were identified and the SLR identified 159 publications, reporting 37 studies in Asia-Pacific. These studies revealed the unmet need for public health education, adequate funding, and staff resourcing, along with greater cooperation between departments and physicians. These actions can help to overcome therapeutic inertia with sufficient follow-up to ensure adherence to recommendations and compliance with treatment. The findings also emphasize the importance of primary care physicians continuing to prescribe treatment and ensure service remains convenient. These findings highlight the limited evidence supporting FLS across the Asia-Pacific region, emphasizing the unmet need for new programs and/or refinement of existing ones to improve outcomes. With the continued increase in burden of fractures in Asia-Pacific, establishment of new FLS and assessment of existing services are warranted to determine the impact of FLS for healthcare professionals, patients, family/caregivers, and society.

Effect of prior deformation on microstructural development and Laves phase precipitation in high-chromium stainless steel.

This study investigated the influence of deformation on precipitation behaviour and microstructure change during annealing. Here, the prior deformation of high-chromium stainless steel was tensile deformation of 3%, 6% and 10%, and the specimens were then annealed at 700˚C for 10 h. The specimens were subsequently analyzed using backscattered electron image and electron backscattering diffraction measurements with SEM. Compared with the deformation microstructure, the grains revealed no preferred orientation. The precipitates of TiN and NbC were formed homogenously in the grain interior and at grain boundaries after annealing. Fine Laves phase precipitates were observed in grains and along subgrain boundaries as the deformation increased. Furthermore, the volume fraction of Laves phase increased, but the average particle diameter of precipitate was reduced as the deformation increased.

Communication: Trapping a proton in argon: Spectroscopy and theory of the proton-bound argon dimer and its solvation.

Ion-molecule complexes of the form H+Arn are produced in pulsed-discharge supersonic expansions containing hydrogen and argon. These ions are analyzed and mass-selected in a reflectron spectrometer and studied with infrared laser photodissociation spectroscopy. Infrared spectra for the n = 3-7 complexes are characterized by a series of strong bands in the 900-2200 cm-1 region. Computational studies at the MP2/aug-cc-pVTZ level examine the structures, binding energies, and infrared spectra for these systems. The core ion responsible for the infrared bands is the proton-bound argon dimer, Ar-H+-Ar, which is progressively solvated by the excess argon. Anharmonic vibrational theory is able to reproduce the vibrational structure, identifying it as arising from the asymmetric proton stretch in combination with multiple quanta of the symmetric argon stretch. Successive addition of argon shifts the proton vibration to lower frequencies, as the charge is delocalized over more ligands. The Ar-H+-Ar core ion has a first solvation sphere of five argons.

Repeated transcranial direct current stimulation reduces food craving in Wistar rats.

It has been suggested that food craving-an intense desire to consume a specific food (particularly foods high in sugar and fat)-can lead to obesity. This behavior has also been associated with abuse of other substances, such as drugs. Both drugs and food cause dependence by acting on brain circuitry involved in reward, motivation, and decision-making processes. The dorsolateral prefrontal cortex (DLPFC) can be activated following evocation and is implicated in alterations in food behavior and craving. Transcranial direct current stimulation (tDCS), a noninvasive brain stimulation technique capable of modulates brain activity significantly, has emerged as a promising treatment to inhibit craving. This technique is considered safe and inexpensive; however, there is scant research using animal models. Such studies could help elucidate the behavioral and molecular mechanisms of eating disorders, including food craving. The aim of our study was to evaluate palatable food consumption in rats receiving tDCS treatment (anode right/cathode left). Eighteen adult male Wistar rats were randomized by weight and divided into three groups (n = 6/group): control, with no stimulation; sham, receiving daily 30 s tDCS (500 µA) sessions for 8 consecutive days; and tDCS, receiving daily 20 min tDCS (500 µA) sessions for 8 consecutive days. All rats were evaluated for locomotor activity and anxiety-like behavior. A palatable food consumption test was performed at baseline and on treatment completion (24 h after the last tDCS session) under fasting and feeding conditions and showed that tDCS decreased food craving, thus corroborating human studies. This result confirms the important role of the prefrontal cortex in food behavior, which can be modulated by noninvasive brain stimulation.

Quantum-mechanical approach to predissociation of water dimers in the vibrational adiabatic representation: Importance of channel interactions.

The results of application of the quantum-mechanical adiabatic theory to vibrational predissociation (VPD) of water dimers, (H2O)2 and (D2O)2, are presented. We consider the VPD processes including the totally symmetric OH mode of the dimer and the bending mode of the fragment. The VPD in the adiabatic representation is induced by breakdown of the vibrational adiabatic approximation, and two types of nonadiabatic coupling matrix elements are involved: one provides the VPD induced by the low-frequency dissociation mode and the other provides the VPD through channel interactions induced by the low-frequency modes. The VPD rate constants were calculated using the Fermi golden rule expression. A closed form for the nonadiabatic transition matrix element between the discrete and continuum states was derived in the Morse potential model. All of the parameters used were obtained from the potential surfaces of the water dimers, which were calculated by the density functional theory procedures. The VPD rate constants for the two processes were calculated in the non-Condon scheme beyond the so-called Condon approximation. The channel interactions in and between the initial and final states were taken into account, and those are found to increase the VPD rates by 3(1) orders of magnitude for the VPD processes in (H2O)2 ((D2O)2). The fraction of the bending-excited donor fragments is larger than that of the bending-excited acceptor fragments. The results obtained by quantum-mechanical approach are compared with both experimental and quasi-classical trajectory calculation results.

The effects of oxygen level and glucose concentration on the metabolism of porcine TMJ disc cells.

OBJECTIVE: To determine the combined effect of oxygen level and glucose concentration on cell viability, ATP production, and matrix synthesis of temporomandibular joint (TMJ) disc cells. DESIGN: TMJ disc cells were isolated from pigs aged 6-8 months and cultured in a monolayer. Cell cultures were preconditioned for 48 h with 0, 1.5, 5, or 25 mM glucose DMEM under 1%, 5%, 10%, or 21% O2 level, respectively. The cell viability was measured using the WST-1 assay. ATP production was determined using the Luciferin-Luciferase assay. Collagen and proteoglycan synthesis were determined by measuring the incorporation of [2, 3-(3)H] proline and [(35)S] sulfate into the cells, respectively. RESULTS: TMJ disc cell viability significantly decreased (P < 0.0001) without glucose. With glucose present, decreased oxygen levels significantly increased viability (P < 0.0001), while a decrease in glucose concentration significantly decreased viability (P < 0.0001). With glucose present, decreasing oxygen levels significantly reduced ATP production (P < 0.0001) and matrix synthesis (P < 0.0001). A decreased glucose concentration significantly decreased collagen synthesis (P < 0.0001). The interaction between glucose and oxygen was significant in regards to cell viability (P < 0.0001), ATP production (P = 0.00015), and collagen (P = 0.0002) and proteoglycan synthesis (P < 0.0001). CONCLUSIONS: Although both glucose and oxygen are important, glucose is the limiting nutrient for TMJ disc cell survival. At low oxygen levels, the production of ATP, collagen, and proteoglycan are severely inhibited. These results suggest that steeper nutrient gradients may exist in the TMJ disc and it may be vulnerable to pathological events that impede nutrient supply.

Viscoelastic shear properties of porcine temporomandibular joint disc.

OBJECTIVES: To investigate the intrinsic viscoelastic shear properties in porcine TMJ discs. MATERIALS AND METHODS: Twelve fresh porcine TMJ discs from young adult pigs (6-8 months) were used. Cylindrical samples (5 mm diameter) with uniform thickness (~1.2 mm) were prepared from five regions of the TMJ disc. Torsional shear tests were performed under 10% compressive strain. Dynamic shear was applied in two methods: 1) a frequency sweep test over the frequency range of 0.1-10 rad/s with a constant shear strain amplitude of 0.05 rad and 2) a strain sweep test over the range of 0.005-0.15 rad at a constant frequency of 10 rad/s. Transient stress relaxation tests were also performed to determine the equilibrium shear properties. RESULTS: As the frequency increased in the frequency sweep test, the dynamic shear complex modulus increased, with values ranging from 7 to 17 kPa. The phase angle, ranging from 11 to 15 degrees, displayed no pattern of regional variation as the frequency increased. The dynamic shear modulus decreased as the shear strain increased. The equilibrium shear modulus had values ranging from 2.6 to 4 kPa. The posterior region had significantly higher values for dynamic shear modulus than those in the anterior region, while no significant regional difference was found for equilibrium shear modulus. CONCLUSION: Our results suggest that the intrinsic region-dependent viscoelastic shear characteristics of TMJ disc may play a crucial role in determining the local strain of the TMJ disc under mechanical loading.

P2 purinergic receptor activation of neuronal nitric oxide synthase and guanylyl cyclase in the dorsal facial area of the medulla increases blood flow in the common carotid arteries of cats.

In the dorsal facial area (DFA) of the medulla, an activation of either P2 purinergic receptor or nitric oxide synthase (NOS) results in the release of glutamate, leading to an increase in blood flow of the common carotid artery (CCA). It is not known whether activation of the P2 receptor by ATP may mediate activation of NOS/guanylyl cyclase to cause glutamate release and/or whether L-Arg (nitric oxide (NO) precursor) may also cause ATP release from any other neuron, to cause an increase in CCA flow. We demonstrated that microinjections of P2 receptor agonists (ATP, α,ß-methylene ATP) or NO precursor (L-arginine) into the DFA increased CCA blood flow. The P2-induced CCA blood flow increase was dose-dependently reduced by pretreatment with NG-nitro-arginine methyl ester (L-NAME, a non-specific NOS inhibitor), 7-nitroindazole (7-NI, a relatively selective neuronal NOS inhibitor) or methylene blue (MB, a guanylyl cyclase inhibitor) but not by that with D-NAME (an isomer of L-NAME) or N5-(1-iminoethyl)-L-ornithine (L-NIO, a potent endothelial NOS inhibitor). Involvement of glutamate release in these responses were substantiated by microdialysis studies, in which perfusions of ATP into the DFA increased the glutamate concentration in dialysates, but co-perfusion of ATP with L-NAME or 7-NI did not. Nevertheless, the arginine-induced CCA blood flow increase was abolished by combined pretreatment of L-NAME and MB, but not affected by pretreatment with a selective P2 receptor antagonist, pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS). In conclusion, ATP activation of the P2 receptor in the DFA induced activation of neuronal NOS/guanylyl cyclase, which causes glutamate release leading to an increase in CCA blood flow. However, arginine activation of neuronal NOS/guanylyl cyclase, which also caused glutamate release and CCA blood flow increase, did not induce activation of P2 receptors. These findings provide important information for drug design and/or developing therapeutic strategies for the diseases associated with CCA blood flow that supplies intra- and extra-cranial tissues.

Examining physiological responses across different driving maneuvers during an on-road driving task: a pilot study comparing older and younger drivers.

OBJECTIVE: This pilot study aimed to investigate physiological responses during an on-road driving task for older and younger drivers. METHODS: Five older drivers (mean age = 74.60 years [2.97]) and 5 younger drivers (mean age = 30.00 years [3.08]) completed a series of cognitive assessments (Montreal Cognitive Assessment [MoCA], Mini Mental Status Examination [MMSE]; Trail Making Test [Trails A and Trails B]) and an on-road driving task along a predetermined, standardized urban route in their own vehicle. Driving performance was observed and scored by a single trained observer using a standardized procedure, where driving behaviors (appropriate and inappropriate) were scored for intersection negotiation, lane changing, and merging. During the on-road driving task, participants' heart rate (HR) was monitored with an unobtrusive physiological monitor. RESULTS: Younger drivers performed significantly better on all cognitive assessments compared to older drivers (MoCA: t(8) = 3.882, P <.01; MMSE: t(8) = 2.954, P <.05; Trails A: t(8) = -2.499, P <.05; Trails B: t(8) = -3.262, P <.05). Analyses of participants' performance during the on-road driving task revealed a high level of appropriate overall driving behavior (M = 87%, SD = 7.62, range = 73-95%), including intersection negotiation (M = 89%, SD = 8.37%), lane changing (M = 100%), and merging (M = 53%, SD = 28.28%). The overall proportion of appropriate driving behavior did not significantly differ across age groups (younger drivers: M = 87.6%, SD = 9.04; older drivers: M = 87.0%, SD = 6.96; t(8) = 0.118, P =.91). CONCLUSIONS: Although older drivers scored lower than younger drivers on the cognitive assessments, there was no indication of cognitive overload among older drivers based on HR response to the on-road driving task. The results provide preliminary evidence that mild age-related cognitive impairment may not pose a motor vehicle crash hazard for the wider older driver population. To maintain safe mobility of the aging population, further research into the specific crash risk factors in the older driver population is warranted.