Background: Postoperative delirium (POD) is a common, transient postoperative cognitive dysfunction in elderly patients. The relationship between POD and intraoperative hypotension remains unclear. This study aims to determine if intraoperative hypotension predicts POD in elderly male patients undergoing laryngectomy. Methods: This study included male patients over 65 years old who underwent laryngectomy between April 2018 and January 2022. The Confusion Assessment Method (CAM) was used to diagnose delirium. Intraoperative hypotension was defined as a Mean Arterial Pressure (MAP) during surgery that was less than 30% of the preoperative level for at least 30 minutes. The relationship between intraoperative hypotension and POD incidence was adjusted for patient demographics and surgery-related factors. Results: Out of 428 male patients, 77 (18.0%) developed POD, and 166 (38.8%) experienced intraoperative hypotension. Surgery duration >= 300 minutes (OR = 1.873, 95% CI 1.041-3.241, p = 0.036), intraoperative hypotension (OR = 1.739, 95% CI 1.039-2.912, p = 0.035), and schooling (OR = 2.655, 95% CI 1.338-5.268) were independent risk factors for POD. The association between intraoperative hypotension and POD was significantly influenced by surgery duration (p for interaction = 0.008), with a stronger association in prolonged surgeries (adjusted OR = 4.902; 95% CI 1.816-13.230). Conclusions: Intraoperative hypotension and low education level are associated with an increased risk of POD in elderly male patients undergoing laryngectomy, especially with prolonged surgery duration. (c) 2024 Sociedade Brasileira de Anestesiologia. Published by Elsevier Espa & ntilde;a, S.L.U. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Objective: In this study, we evaluated the pH (potential of hydrogen) value of diabetic foot ulcers and explored the relationship between the pH value and infection, sinus formation, stasis dermatitis, and the process of healing. Methods: From October 2022 to June 2023, 99 patients with 106 diabetic foot ulcers were selected. Diabetic foot ulcers were treated in a standardized manner by a professional team. The pH value, area, PUSH (Pressure Ulcer Scale for Healing) score, and the degree of infection of the wounds were compared before and after the treatment. Results: The baseline wound pH value in 76.4% of the patients was in the alkaline range and was closely related to the degree of infection (P < 0.05). As the ulcers healed, the pH decreased. For moderately and severely infected diabetic foot ulcers, each unit decrease in pH was associated with a decrease in the PUSH score of approximately 4.6 points (P < 0.05). The pH values of wounds with surrounding ecchymosis dermatitis were significantly higher than those of wounds without ecchymosis dermatitis (P < 0.05). The pH value of the wound with a sinus tract was higher. After treatment, there was no significant difference in pH value between the patients with and without sinus tracts (P < 0.05). Conclusions: The measurement of pH value is efficient and simple, and the patient suffers no discomfort in the process. The change in pH helps predict the healing process of diabetic foot ulcers and quickly identify whether there are key factors such as infection and ischemia in the wound. It is suggested that dynamic pH monitoring be included in the whole course evaluation and intervention strategy development of diabetic foot.

To effectively address underlying issues and enhance the healing process of hard-to-treat soft tissue defects, innovative therapeutic approaches are required. One promising strategy involves the incorporation of bioactive substances into biodegradable scaffolds to facilitate synergistic tissue regeneration, particularly in vascular regeneration. In this study, we introduce a composite hydrogel design that mimics the extracellular matrix by covalently combining gelatin and hyaluronic acid (HA), with the encapsulation of deferoxamine nanoparticles (DFO NPs) for potential tissue regeneration applications. Crosslinked hydrogels were fabricated by controlling the ratio of HA in the gelatin-based hydrogels, resulting in improved mechanical properties, enhanced degradation ability, and optimised porosity, compared with hydrogel formed by gelatin alone. The DFO NPs, synthesized using a double emulsion method with poly (D,L-lactide-co-glycolide acid), exhibited a sustained release of DFO over 12 d. Encapsulating the DFO NPs in the hydrogel enabled controlled release over 15 d. The DFO NPs, composite hydrogel, and the DFO NPs loaded hydrogel exhibited excellent cytocompatibility and promoted cell proliferationin vitro. Subcutaneous implantation of the composite hydrogel and the DFO NPs loaded hydrogel demonstrated biodegradability, tissue integration, and no obvious adverse effects, evidenced by histological analysis. Furthermore, the DFO NPs loaded composite hydrogel exhibited accelerated wound closure and promoted neovascularisation and granular formation when tested in an excisional skin wound model in mice. These findings highlight the potential of our composite hydrogel system for promoting the faster healing of diabetes-induced skin wounds and oral lesions through its ability to modulate tissue regeneration processes.

Purpose:To examine whether intraoperative dexmedetomidine reduces postoperative delirium (POD) in elderly patients who underwent a laryngectomy. Methods:Patients were randomly assigned to receive dexmedetomidine or a saline placebo infused during surgery. The study period was July 2020 to January 2022. Participants were elderly individuals (≥65 years) who underwent a laryngectomy. Immediately after induction of anesthesia, a 0.5 μg.kg-1 bolus of study solution was administered for 10 min, followed by a maintenance infusion of 0.2 μg.kg-1.hr-1 until the end of surgery. Patients were assessed daily for POD (primary outcome). Plasma inflammatory factors were measured at baseline, on the first postoperative day, and on the third postoperative day. Results:In total, 304 male patients were randomized; 299 patients [median (interquartile range) age, 69.0 (67.0-73.0) years] completed in-hospital delirium assessments. There was no difference in the incidence of POD between the dexmedetomidine and control groups (21.3% [32 of 150] vs 24.2% [36 of 149], P=0.560). However, dexmedetomidine reduced POD in patients with laryngeal cancer and a higher tumor stage (21.6% vs 38.5%; OR, 0.441; 95% CI, 0.209-0.979; P=0.039). Dexmedetomidine reduced levels of C-reactive protein (CRP) (P=0.0056) and interleukin 6 (IL-6) (P<0.001) on the first and third postoperative days, respectively. More patients had intraoperative hypotension in the dexmedetomidine group (29.3% [44 of 150] vs 17.4% [26 of 149], P=0.015). Conclusion:Intraoperative dexmedetomidine administration did not prevent POD in patients with laryngeal cancer. Dexmedetomidine reduced serum CRP and IL-6 levels postoperatively but caused a higher occurrence of intraoperative hypotension in elderly patients after a laryngectomy.

Slip-induced falls are a growing health concern for older adults, and near-fall events are associated with an increased risk of falling. To detect older adults at a high risk of slip-related falls, this study aimed to develop models for near-fall event detection based on accelerometry data collected by body-fixed sensors. Thirty-four healthy older adults who experienced 24 laboratory-induced slips were included. The slip outcomes were first identified as loss of balance (LOB) and no LOB (NLOB), and then the kinematic measures were compared between these two outcomes. Next, all the slip trials were split into a training set (90%) and a test set (10%) at sample level. The training set was used to train both machine learning models (n = 2) and deep learning models (n = 2), and the test set was used to evaluate the performance of each model. Our results indicated that the deep learning models showed higher accuracy for both LOB (>64%) and NLOB (>90%) classifications than the machine learning models. Among all the models, the Inception model showed the highest classification accuracy (87.5%) and the largest area under the receiver operating characteristic curve (AUC), indicating that the model is an effective method for near-fall (LOB) detection. Our approach can be helpful in identifying individuals at the risk of slip-related falls before they experience an actual fall.

The objective of the study is to explore the status quo of foot pruritus and related factors in elderly diabetics and provide a reference for targeted preventive measures. The study involved a survey using a self-designed foot pruritus assessment scale to understand the status quo of foot pruritus among 411 cases of elderly diabetics from 5 communities in Shanghai. The morbidity rate of foot pruritus in elderly diabetics in the community was 20.1%. Good self-management behaviour was the protective factor, while diabetic peripheral neuropathy, hyperlipidemia, and dry skin were risk factors (all P < 0.05). The incidence of foot pruritus in elderly diabetics was high and influenced by several factors. We recommend that self-management behaviour of patients be improved. Additionally, screening and interventions to address hyperlipidemia, diabetic peripheral neuropathy, and dry skin should be conducted regularly to prevent diabetic foot ulcers.

This study examined the effects of perturbation training on the contextual interference and generalization of encountering a novel opposing perturbation. One hundred and sixty-nine community-dwelling healthy older adults (69.6 ± 6.4 years) were randomly assigned to one of the three groups: slip-perturbation training (St, n = 67) group received 24 slips, trip-perturbation training (Tt, n = 67) group received 24 trips, and control (Ctrl: n = 31) group received only non-perturbed walking trials ( ClinicalTrials.gov NCT03199729; https://clinicaltrials.gov/ct2/show/NCT03199729 ). After training, all groups had 30 min of rest and three post-training non-perturbed walking trials, followed by a reslip and a novel trip trial for St, a retrip and a novel slip trial for Tt, and randomized novel slip and trip trials for Ctrl. The margin of stability (MOS), step length, and toe clearance of post-training walking trials were compared among three groups to examine interferences in proactive adjustment. Falls, MOS at the instant of recovery foot touchdown, and hip height of post-training perturbation trials were investigated to detect interferences and generalization in reactive responses. Results indicated that prior adaptation to slip perturbation training, resulting in walking with a greater MOS (more anterior) and a shorter step length ( p < 0.01) than that of the Ctrl group, would be associated with a greater likelihood to forward balance loss if encountered with a trip. The trip adaptation training mainly induced a higher toe clearance during walking ( p < 0.01) than the Ctrl group, which could lead to reduced effectiveness of the reactive response when encountered with a novel slip. However, there was no difference in the reactive MOS, limb support, and falls between the control group and the slip and trip training groups on their respective opposing novel perturbation post-training (MOS, limb support, and falls for novel slip: Tt = Ctrl; for the novel trip: St = Ctrl, both p > 0.05). Current findings suggested that, although perturbation training results in proactive adjustments that could worsen the reactive response (interference) when exposed to an unexpected opposing perturbation, older adults demonstrated the ability to immediately generalize the training-induced adaptive reactive control to maintain MOS, to preserve limb support control, and to reduce fall risk.

Purpose To determine the relationships between postoperative delirium (POD) and postoperative activities of daily living (ADL) and mortality in patients undergoing laryngectomy. We hypothesized that POD would reduce postoperative ADL and increase postoperative mortality. Patients and Methods The prospective study included older participants (age ≥65 y) undergoing total laryngectomy, partial laryngectomy, total laryngectomy plus neck dissection, or partial laryngectomy plus neck dissection under general anesthesia. The diagnosis of delirium was based on the Confusion Assessment Method algorithm, which was administered on postoperative days 1 through 6. ADL were evaluated using the Chinese version of the Index of ADL scale. Follow-up assessments of ADL and mortality were conducted 24 months after surgery. Results Of 127 participants (aged 70.3 ± 4.1 y), 19 (15.0%) developed POD. POD was not associated with a decrease in ADL after laryngectomy (p=0.599) nor with an increase in postoperative mortality [3/19 (15.8%) vs 12/108 (11.1%), p=0.560, Log rank test]. However, longer surgery duration was significantly associated with worse overall survival (OR, 3.262; 95% CI, 1.261–9.169, p=0.025). Conclusion POD was not associated with long-term ADL or mortality after laryngectomy. Prolonged surgery was the only factor associated with a higher postoperative mortality rate.

Background Trips account for over half of outdoor falls among community-dwelling older adults. Aims To investigate to what extent obstacle-induced trip-perturbation training could reduce fall-risk among older adults and to see whether training effects could be retained short term. Methods Forty community-dwelling older adults were exposed to 24 repeated trip-perturbations given in a “blocked-and-mixed” manner during over-ground gait. Another trip was given 30 min post-training. For each trip, recovery strategies and outcomes (fall versus no fall) were analyzed. Within-trial changes to proactive and reactive dynamic center of mass stability, pre-trip toe clearance and trunk angle, trunk angle at recovery completion, and recovery step length were analyzed. Results 48% of participants fell on their novel trip. The fall rate decreased significantly for subsequent trips, with no falls on the last trip. The decreased fall incidence resulted from improved feedforward and feedback adjustments for controlling center of mass stability and body kinematics. Proactive adaptations included reduced forward center of mass velocity, which lessened forward instability, and larger toe clearance, which increased the likelihood of obstacle avoidance. Reactive adjustments included reduced forward instability and improved trunk control (reduced forward rotation) at recovery step completion. Post-training, training effects were retained in terms of fall incidence, with slight decay in toe clearance and reactive stability. Conclusions Older adults demonstrated appropriate locomotor-based proactive and reactive adaptations to repeated obstacle-induced trips with short-term retention similar to young adults, and thus could reduce their fall-risk through such training.

Slip outcomes are categorized as either a backward loss of balance (LOB) or a no loss of balance (no-LOB) in which an individual does not take a backward step to regain their stability. LOB includes falls and nonfalls, while no-LOB includes skate overs and walkovers. Researchers are uncertain about which factors determine slip outcomes and at which critical instants they do so. The purpose of the study was to investigate factors affecting slip outcomes in proactive and early reactive phases by analyzing 136 slip trials from 68 participants (age: 72.2 [5.3] y, female: 22). Segment angles and average joint moments in the sagittal plane of the slipping limb were compared for different slip outcomes. The results showed that knee flexor, hip extensor, and plantar flexor moments were significantly larger for no-LOB than for LOB in the midproactive phase, leading to smaller shank-ground and foot-ground angles at the slip onset, based on forward dynamics. In the early reactive phase, the hip extensor and plantar flexor moments were larger for no-LOB than for LOB, and all segment angles were smaller for no-LOB. Our findings indicate that the shank angle and knee moment were the major determinants of slip outcomes in both proactive and reactive phases.

Background: As age progresses, decline in physical function predisposes older adults to high fall-risk, especially on exposure to environmental perturbations such as slips and trips. However, there is limited evidence of association between daily community ambulation, an easily modifiable factor of physical activity (PA), and fall-risk. Smartphones, equipped with accelerometers, can quantify, and display daily ambulation-related PA simplistically in terms of number of steps. If any association between daily steps and fall-risks is established, smartphones due to its convenience and prevalence could provide health professionals with a meaningful outcome measure, in addition to existing clinical measurements, to identify older adults at high fall-risk. Objective: This study aimed to explore whether smartphone-derived step data during older adults' community ambulation alone or together with commonly used clinical fall-risk measurements could predict falls following laboratory-induced real-life like slips and trips. Relationship between step data and PA questionnaire and clinical fall-risk assessments were examined as well. Methods: Forty-nine community-dwelling older adults (age 60–90 years) completed Berg Balance Scale (BBS), Activities-specific Balance Confidence scale (ABC), Timed Up-and-Go (TUG), and Physical Activity Scale for the Elderly (PASE). One-week and 1-month smartphone steps data were retrieved. Participants' 1-year fall history was noted. All participants' fall outcomes to laboratory-induced slip-and-trip perturbations were recorded. Logistic regression was performed to identify a model that best predicts laboratory falls. Pearson correlations examined relationships between study variables. Results: A model including age, TUG, and fall history significantly predicted laboratory falls with a sensitivity of 94.3%, specificity of 58.3%, and an overall accuracy of 85.1%. Neither 1-week nor 1-month steps data could predict laboratory falls. One-month steps data significantly positively correlated with BBS (r = 0.386, p = 0.006) and ABC (r = 0.369, p = 0.012), and negatively correlated with fall history (rp = −0.293, p = 0.041). Conclusion: Older participants with fall history and higher TUG scores were more likely to fall in the laboratory. No association between smartphone steps data and laboratory fall-risk was established in our study population of healthy community-dwelling older adults which calls for further studies on varied populations. Although modest, results do reveal a relationship between steps data and functional balance deficits and fear of falls.

The purpose was to examine and compare the longer-term generalization between 2 different practice dosages for a single-session treadmill slip-perturbation training when reexposed to an overground slip 6 months later. A total of 45 older adults were conveniently assigned to either 24 or 40 slip-like treadmill perturbation trials or a third control group. Overground slips were given immediately after initial training, and at 6 months after initial training in order to examine immediate and longer-term effects. The performance (center of mass stability and vertical limb support) and fall percentage from the laboratory-induced overground slips (at initial posttraining and at 6 mo) were measured and compared between groups. Both treadmill slip-perturbation groups showed immediate generalization at the initial posttraining test and longer-term generalization at the 6-month retest. The higher-practice-dosage group performed significantly better than the control group (P < .05), with no difference between the lower-practice-dosage and the control groups at the 6-month retest (P > .05). A single session of treadmill slip-perturbation training showed a positive effect for reducing older adults' fall risk for laboratory-induced overground slips. A higher-practice dosage of treadmill slip perturbations could be more beneficial for further reducing fall risk.

目的 观察喉癌术后谵妄患者血清过氧化物酶体增殖物激活受体-γ(peroxisome proliferatoractivated receptor-γ,PPAR-γ)蛋白和炎症介质表达水平的变化.方法 纳入126例因喉癌在我院进行手术治疗的老年男性患者,共有18例发生术后谵妄(术后谵妄组).以年龄和疾病累计评分作为匹配条件,共有50例未发生术后谵妄的患者进入对照组.记录2组患者术前和术后第1天的血清PPAR-γ蛋白、白细胞介素-6(IL-6)、C反应蛋白(CRP)和皮质醇水平.结果 术前2组患者的血清PPAR-γ、IL-6、CRP水平差异无统计学意义(P＞0.05),但术后谵妄组患者皮质醇水平高于对照组(P =0.002).术后第1天,术后谵妄组患者血清PPAR-γ水平低于对照组(P=0.046),IL-6水平高于对照组(P ＜0.000 1),皮质醇水平仍然高于对照组(P=0.0009),2组间CRP水平差异无统计学意义(P＞0.05).结论 老年喉癌术后谵妄患者处于炎症促发状态,PPAR-γ、IL-6和皮质醇可能参与术后谵妄的发生、发展.

Objective To explore the risk factors and incidence of postoperative delirium (POD) in patients undergoing laryngectomy for laryngeal cancer. Study Design Prospective cohort study. Setting Shanghai Eye, Ear, Nose, and Throat Hospital, Fudan University. Subjects and Methods A total of 323 patients underwent laryngectomy from April 4, 2018, to December 28, 2018. Perioperative data were collected. The primary outcome was the presence of POD as defined by the Confusion Assessment Method diagnostic algorithm. Univariate and multivariable logistic regression analyses were used to identify risk factors associated with POD. Results Of the patients who underwent laryngectomy during the study period, 99.1% were male, with a mean age of 60.0 years. Of these patients, 28 developed POD, with most episodes (88.1%) occurring during the first 3 postoperative days. The type of POD was hyperactive in 7 cases and hypoactive in 21 cases. The mean duration of POD was 1 day. The mean Delirium Rating Scale-Revised-98 score (a measure of POD severity) was 11.5. For the multivariable analysis, risk factors associated with POD included advanced cancer stage, lower educational level, higher American Society of Anesthesiologists classification, and intraoperative hypotension lasting at least 30 minutes. Intraoperative dexmedetomidine use was protective against POD. Conclusion This study identified risk factors associated with POD, providing a target population for quality improvement initiatives. Furthermore, intraoperative dexmedetomidine use can reduce POD.

Aging-associated fall-risk assessment is crucial for fall prevention. Thus, this study aimed to develop a prognostic model to predict fall-risk following an unexpected over-ground slip perturbation based on normal gait pattern in healthy older adults. 112 healthy older adults who experienced a novel slip in a safe laboratory environment were included. Their slip trial and natural walking trial immediately prior to it were analyzed. To identify the best fall-risk predictive model, gait related variables including step length, segment angles, center of mass state, and ground reaction force (GRF) were determined and inputted into a stepwise logistic regression. The optimal slip-induced fall prediction model was based on the right thigh angle at slipping foot touchdown (TD), the maximum GRF of the slipping limb after TD, and the momentum change from TD to recovery foot liftoff (LO), with an overall prediction accuracy of 75.9%, predicting 74.5% of falls (sensitivity) and 77.2% of recoveries (specificity). Conversely, a model based on clinical and demographic measures predicted 78.2% of falls and 47.4% of recoveries, resulting in a much lower overall accuracy of 62.5%. The fall-risk model based on normal gait pattern which was developed for slip-induced perturbations in healthy older adults was able to provide a high predictive accuracy. This information could provide insight about the ideal normal gait measures which could be used to contribute towards development of therapeutic strategies related to dynamic balance and fall prevention to enhance preventive interventions in populations with high-risk for slip-induced falls.

Background: Preoperative psychologic distress is common in head and neck cancer patients and related to deleterious effects in patient treatment and recovery. Routine screening and appropriate referral of all patients with cancer for psychiatric assessment is now a part of the medical treatment. Objects: The aim was to assess the level of preoperative psychologic distress in laryngeal cancer patients scheduled for surgical treatment. Methods: After the Institutional Review Board approval and informed written consent, 211 patients scheduled for total or partial laryngectomy were interviewed preoperatively. Each patient was asked to fulfil the Hospital Anxiety and Depression Scale. Demographic characteristics that may relate to psychologic distress were also recorded. Results: The mean age (+/-SD) was 62.1 (8.2) years. The surgical type was total laryngectomy (n = 79) and partial laryngectomy (n = 132). Median (first/third quartile) HADS score was 6 (3/10). A total of 39.6% patients had psychologic distress. The HADS score was higher for total laryngectomy patients than partial laryngectomy patients [7 (4/10) versus 5 (3/10), p < .05]. Age was negatively correlated with HADS score (p = .049). Conclusions: Our study showed that laryngeal cancer patients scheduled for total laryngectomy had higher level of psychologic distress. Age was a predictive factor for psychologic distress.

The study purpose was to investigate whether older adults could improve their stability against a backward loss of balance (BLOB) after receiving repeated treadmill slips during walking and to see how such adaptive changes would be affected by practice dosage (combination of slip intensity and the number of slips at each intensity). Twenty-five healthy community-dwelling older adults received forty treadmill slips given over eleven blocks at five intensities (P1–P1–P2–P3–P4–P5–P4–P5–P5–P3–P1, larger number indicating higher intensity). Center of mass (COM) stability was calculated as the shortest distance of the instantaneous COM position and velocity relative to the base of support (BOS) from a theoretical threshold for BLOB (larger stability value indicated a better stability against BLOB). Stability, step length, and trunk angle were measured before and after slip onset to reflect proactive and reactive control, respectively. The first slips at each intensity block (i.e., P1, P3, P4, and P5) were compared with the first slips in the last blocks at those intensities to examine main effects of training dosage (intensity and repetition). Improvements in proactive and reactive stability were more pronounced for receiving more slips at larger intensities than fewer slips at smaller intensities. Older adults only demonstrated partial positive scaling effects to proactively, not reactively, establish a more stable initial COM state. The improved proactive stability was associated with an anterior shift of COM position relative to the BOS, resulting from a shorter pre-slip step length. The improved reactive stability was associated with an anterior shift of COM position, resulting from a larger compensatory step length and a faster COM velocity relative to the BOS. Our findings indicated that treadmill-gait slip perturbations elicited similar proactive and reactive control to that from over-ground slip perturbations, but greater slip intensity and repetition might yield more immediate adaptive improvements.

The purpose of this study was to determine any potential falls-resistance benefits that might arise from treadmill-slip-perturbation training. One hundred sixty-six healthy community-dwelling older adults were randomly assigned to either the treadmill-slip-training group (Tt) or the treadmill-control group (Tc). Tt received 40 slip-like perturbations during treadmill walking. Tc received unperturbed treadmill walking for 30 min. Following their treadmill session, both groups were exposed to a novel slip during over-ground walking. Their responses to this novel slip were also compared to previously collected data from participants who received either over-ground-slip training (Ot) with 24 slips or over-ground walking (Oc) with no training before experiencing their novel over-ground slip. Fall rates and both proactive (pre-slip) and reactive (post-slip) stability were assessed and compared for the novel over-ground slip in groups Tt, Tc, and Oc, as well as for the 24th slip in Ot. Results showed Tt had fewer falls than Tc (9.6% versus 43.8%, p < 0.001) but more falls than Ot (9.6% versus 0%, p < 0.001). Tt also had greater proactive and reactive stability than Tc (Tt > Tc, p < 0.01), however, Tt's stabilities were lower than those of Ot (p < 0.01). There was no difference in fall-rate or reactive stability between Tc and Oc, though treadmill walking did improve the proactive stability control of the latter. While the treadmill-slip-training protocol could immediately reduce the numbers of falls from a novel laboratory-reproduced slip, such improvements were far less than that from the motor adaptation to the over-ground-slip-training protocol.

Postoperative delirium (POD) is a neurobehavioral syndrome caused by dysfunction of neural activity mainly in elderly people. POD is not uncommon, but under-recognized, and often serious. Multifactorial causes including aging, acetylcholine deficiency, sleep deprivation and intraoperative hypoxia have been proposed attempting to explain the processes leading to the development of POD. To date, however, no specific pathophysiologic mechanism has been identified. Here, we summarize the five most prominent theories (neuronal aging, neuroinflammation, neurotransmitter imbalance, neuroendocrine activation, and network connectivity change) to explain the development of delirium. Understanding of the neuropathogenesis of delirium will help focus future research, and assist in developing prophylactic and treatment strategies.

BACKGROUND:Perturbation training is an emerging paradigm to reduce idiopathic falls (without clinical signs or symptoms) in older adults. While a higher threat dosage (intensity) in motor learning often directly relates to greater adaptation, retention, and generalization, little is known whether increasing the practice dosage (repetition) of slip-perturbation training would necessarily improve its outcomes. RESEARCH QUESTION:Can higher practice dosage of treadmill slip-perturbation training lead to greater generalization to an overground slip immediately after the training? METHODS:Forty-five community-dwelling older adults (73.5 ± 5.6 years old) participated in the present study. They were conveniently assigned to three groups with equivalent treadmill walking duration: treadmill slip-perturbation training group with 40 practice dosage, 24 practice dosage, and zero practice dosage (without slip-perturbation). Later on during overground walking, all of them were exposed to the same generalization test (a novel slip on a walkway). Their recovery outcomes (fall, or no fall; balance loss, or no balance loss) and center of mass stability were compared. RESULTS:Higher practice dosage did not show significantly less incidence of fall, balance loss, or greater stability in comparison to lower practice dosage (p > .05). The present study showed that there was no evidence of dose-response relationship when the practice dosage was set above the 24 trials of practice dosage in treadmill slip-perturbation training. SIGNIFICANCE:Contrary to our hypothesis, increased practice dosage (40-slips) in treadmill slip-perturbation training from the commonly used threshold (24-slips) did not necessarily benefit immediate generalization from treadmill to overground walking among community-dwelling older adults.