Hindbrain Double-Negative Feedback Mediates Palatability-Guided Food and Water Consumption.

Hunger and thirst have distinct goals but control similar ingestive behaviors, and little is known about neural processes that are shared between these behavioral states. We identify glutamatergic neurons in the peri-locus coeruleus (periLCVGLUT2 neurons) as a polysynaptic convergence node from separate energy-sensitive and hydration-sensitive cell populations. We develop methods for stable hindbrain calcium imaging in free-moving mice, which show that periLCVGLUT2 neurons are tuned to ingestive behaviors and respond similarly to food or water consumption. PeriLCVGLUT2 neurons are scalably inhibited by palatability and homeostatic need during consumption. Inhibition of periLCVGLUT2 neurons is rewarding and increases consumption by enhancing palatability and prolonging ingestion duration. These properties comprise a double-negative feedback relationship that sustains food or water consumption without affecting food- or water-seeking. PeriLCVGLUT2 neurons are a hub between hunger and thirst that specifically controls motivation for food and water ingestion, which is a factor that contributes to hedonic overeating and obesity.

Thirst and drugs: A study in the World Health Organization's pharmacovigilance database.

Thirst is a complex physiological compensatory mechanism but could also be associated with drugs. This association was poorly investigated previously. Using the WHO global pharmacovigilance database, Vigibase®, disproportionality analyses potential associations between exposure to drugs and thirst reports were performed. All reports of thirst in adults between 01/01/2000 and 31/12/2023 were included. Results are expressed as reporting odds ratio (ROR). Analysis of the 3186 reports of thirst (978 'serious') allowed, first, to confirm the association between thirst and exposure to vasopressin antagonists (tolvaptan), lithium, gliflozins (dapagliflozin, empagliflozin), pregabalin and antimuscarinic drugs (glycopyronium, oxybutynin, tiotropium). Second, new safety signals were described with monoamine reuptake inhibitors (antidepressants: duloxetine, venlafaxine; anti-obesity agent: sibutramine), antipsychotic (olanzapine), glucocorticoid (prednisolone), diuretic (furosemide) drugs as well with ribavirin or sodium oxybate. This study is the first to offer a list of drugs associated with thirst in humans.

Is increased subjective thirst associated with greater interdialytic weight gains, extracellular fluid and dietary sodium intake?

BACKGROUND: Some previous studies have reported an effect of increasing subjective thirst and interdialytic weight gains (IDWG), and that this may be influenced by nonadherence to dietary sodium restrictions, whereas others reported no such association. As such we wished to review the effect of self-reported thirst on IDWGs and dietary sodium intake. METHODS: Dialysis patients were asked to complete visual analogues thirst, distress thermometer (DT) scores and complete a sodium food frequency questionnaire (SFFQ). IDWG and pre and post dialysis volumes were measured with multifrequency bioelectrical impedance. RESULTS: One hundred and eleven patients completed the questionnaires and had bioimpedance measurements: 63% male, mean age 63.8 ± 16.1 years, 33% diabetic with a median thirst score 3 (0-5) and SFFQ 52.0 ± 18, and IDWG 2.1 ± 1.3%. Thirst was associated with DT (r = 0.28, p = 0.004) and negatively with age (r = -0.31, p < 0.001), but not SFFQ, IDWG, extracellular water, or dialysate sodium, or dialysate to plasma gradient. Patients with higher thirst scores were younger (58.0 ± 15.2 vs. 69.4 ± 15.0 years, p < 0.001) with higher DT scores (5 [2-7] vs. 2 [0-5], p < 0.001). On multivariate logistic analysis, only age was associated with self-reported thirst (odds ratio 0.95, 95% confidence limits 0.92-0.98, p < 0.001). CONCLUSION: We found that subjective thirst was greater for younger patients and those who reported higher levels of distress, but no association with IDWGs, dietary sodium intake, or dialysate sodium. However, most of our patients followed the dietary advice, as evidenced by the low SFFQ scores and % IDWGs. Whether thirst increases distress or distress increases subjective thirst remains to be determined.

Parent-offspring similarity in hunger and thirst sensations.

The internal (i.e., interoceptive) sensations that characterise hunger vary between people, and this may also be the case for thirst, although it has not been so well explored. There are probably both heritable and learning-based causes for this interoceptive variability. Consequently, it would seem plausible that parents and their offspring would have more similar patterns of hunger and thirst than pairs of strangers. We tested this idea, in addition to exploring its potential moderating variables, by studying the similarity of self-reported hunger and thirst sensations in 170 students and their primary caregivers from childhood. Both students and caregivers completed the same online-survey, covering hunger and thirst sensations, beliefs about the causes of hunger and thirst, the Three Factor Eating Questionnaire (revised) and demographic data. We find evidence of robust student-caregiver similarity in interoceptive hunger and thirst sensations (medium effect sizes), with these being moderated by caregiver beliefs about the homeostatic nature of each state (medium effect sizes). This suggests a potential role for caregivers in the development of their offspring's interoceptive cues for hunger and for thirst. In addition, thirst, like hunger, appears to be multidimensional, and varies between people. The implications of these findings are discussed.

Rational regulation of water-seeking effort in rodents.

In the laboratory, animals' motivation to work tends to be positively correlated with reward magnitude. But in nature, rewards earned by work are essential to survival (e.g., working to find water), and the payoff of that work can vary on long timescales (e.g., seasonally). Under these constraints, the strategy of working less when rewards are small could be fatal. We found that instead, rats in a closed economy did more work for water rewards when the rewards were stably smaller, a phenomenon also observed in human labor supply curves. Like human consumers, rats showed elasticity of demand, consuming far more water per day when its price in effort was lower. The neural mechanisms underlying such "rational" market behaviors remain largely unexplored. We propose a dynamic utility maximization model that can account for the dependence of rat labor supply (trials/day) on the wage rate (milliliter/trial) and also predict the temporal dynamics of when rats work. Based on data from mice, we hypothesize that glutamatergic neurons in the subfornical organ in lamina terminalis continuously compute the instantaneous marginal utility of voluntary work for water reward and causally determine the amount and timing of work.

Caregivers' Attention Toward, and Response to, Their Child's Interoceptive Hunger and Thirst Cues.

People can use their internal state to determine if they are hungry or thirsty. Although the meaning of some interoceptive cues may be innate (e.g., pain), it is possible that others-including those for hunger and thirst-are acquired. There has been little exploration of this idea in humans. Consequently, we conducted a survey among child caregivers to determine if the basic conditions necessary for interoceptive learning were present. Two-hundred and thirty-five caregivers of children aged 1-12 years were asked if they had recently noticed stomach rumbling, hunger-related irritability, and a dry mouth in their child. They were also asked how they would respond. The impact of several moderating variables, especially caregiver beliefs about the causes of hunger, fullness, and thirst, was also explored. Fifteen percent of caregivers had recently noticed stomach rumbling in their child, 28% hunger-related irritability, and 14% a dry mouth. Forty-four percent of caregivers had noticed at least one of these three cues. Noticing hunger cues was significantly moderated by caregiver beliefs about their cause, by child age, and in one case by temporal context (around vs. outside mealtimes). Key caregiver responses were providing the need (e.g., offer food) and/or asking the child if they had a need (e.g., hungry?). Each type of response could potentially support a different form of interoceptive learning. In conclusion, we suggest the necessary conditions for children to learn interoceptive hunger and thirst cues, are present in many caregiver-offspring dyads.

Thirst symptoms in patients with heart failure: An integrative review.

AIM: To identify the risk and protective factors affecting thirst symptoms in patients with heart failure (HF) and intervention strategies to alleviate thirst symptoms. DESIGN: An integrative review. METHODS: A total of 61 articles were retrieved. Screening yielded a total of 21 articles which were appraised for quality. The quality of studies was assessed using the Mixed Methods Appraisal Tool. DATA SOURCES: Ten electronic databases were searched in October 2023, including Embase, Pubmed, CINAHL, Cochrane, Web of Science, Wiley, CNKI, VIP, CBM and WanFang. In addition, we searched grey databases and manually searched reference lists of included and relevant reviews. RESULTS: In total, 1644 articles were retrieved, of which 21 were included. Eight studies addressed the factors. Six themes emerged as risk factors, including demographics, severity of disease, psycho-environmental, medication, fluid restriction and homeostasis. Conversely, an increase in fluid intake, a high score of sodium restriction diet attitude and using ARB were identified as protective factors. Thirteen studies focus on intervention strategies. Five unique intervention strategies were identified, including Traditional Chinese Medicine, mint-related interventions, sour-flavour interventions, improved water restriction and cluster nursing strategy. CONCLUSION: This finding identified the factors associated with thirst symptoms in patients with HF, especially concerning the elaboration of risk factors, which suggests that healthcare professionals should focus on the risk factors for thirst in patients with HF and consciously avoid the occurrence of these risk factors. Additionally, there are considerable cultural differences in interventions, therefore, to increase adherence during symptom management, careful selection of appropriate intervention strategies based on the requirements and preferences of patients is required. While there are some therapies, there aren't enough high-quality empirical investigations. Thus, multi-centre, large-sample studies are also required in subsequent research to demonstrate the interventions' effectiveness. IMPLICATIONS FOR THE PROFESSION: The nurse must notice the symptoms of thirst in HF to slow down the disease's progression and improve the patient's physical and emotional well-being. REPORTING METHOD: The review complies with the PRISMA guidelines for reporting systematic reviews. PATIENT OR PUBLIC CONTRIBUTION: No patient or public contribution.

The Effect of Cold Oral Applications in the Management of Postoperative Thirst: A Systematic Review.

PURPOSE: Thirst is one of the most bothersome symptoms experienced by surgical patients. Effective thirst intervention and management in the Post Anesthesia Care Unit (PACU) and hospital wards is critical because patients are less sedated and more aware than in the past. There is a need to review the literature on the identification and management of thirst in the inpatient and PACU settings. The aim of this systematic review was to examine the available evidence on the effectiveness of oral cold applications on thirst in postoperative patients. DESIGN: This was a systematic review study. Articles in PUBMED, Web of Science, ScienceDirect, TÜBITAK-ULAKBIM, and TRDizin databases between January 2008 and January 2023 that included oral cold applications to relieve the thirst of patients in the postoperative period were included. METHODS: The PICOT-SD (Patients Interventions Comparison Outcome Time-Study Design) method was used as an eligibility criterion for inclusion in the study. The eligibility criteria included that the articles were written in English-Turkish and within the target dates, the studies included nursing interventions, the primary outcome of the studies was thirst, and the study sample included postoperative patients. The risk of bias was assessed using the RoB2 tool developed by Cochrane. FINDINGS: A total of 254 articles were retrieved from the databases using the specified keywords. 244 articles did not meet the study criteria: 30 were excluded because they were not interventional studies, 61 were not conducted in a postoperative population, 56 were duplicates, and 79 were not on a related topic. A total of 10 studies consisting of randomized controlled trials and quasi-experimental articles met the criteria for our review. Oral cold applications effectively reduced the thirst rate of postoperative patients and improved their health-related quality of life. The intervention has also been shown to reduce other anesthesia-related complications. CONCLUSIONS: This systematic review concluded that cold oral applications have promising effects on thirst, dry mouth, and health-related quality of life. Cold oral applications are cost-effective and suitable for large-scale health care applications.

The Prevalence and Risk Factors for Postoperative Thirst: A Systematic Review and Meta-analysis.

PURPOSE: Thirst is a symptom of dehydration and one of the main complications affecting postoperative outcomes and comfort. Persistent water scarcity can have a detrimental effect on the cognitive function and psychology of patients. However, the current evidence about the prevalence and risk factors for postoperative thirst is not fully understood. Therefore, this study aims to investigate the prevalence and risk factors of postoperative thirst and provide guidance for clinical practice. DESIGN: Systematic review and meta-analysis. METHODS: We searched PubMed, Cochrane Library, Web of Science, Embase, Clinicaltrials.gov, China National Knowledge Infrastructure, and Wanfang Database. Eligible studies were evaluated using the Agency for Healthcare Research and Quality. The collected data were pooled and analyzed using Stata15.0. FINDINGS: A total of 11 cross-sectional studies were included involving 20,612 patients. Eight studies reported prevalence and the pooled prevalence of postoperative thirst was 76.8% (95% confidence interval [CI]: 0.664 to 0.858). Five studies contributed to meta-syntheses of risk factors for postoperative thirst. The results indicated that sex (odds ratio [OR] = 1.44, 95% CI = 1.13 to 1.84, I2 = 80.2%, P = .006), anesthesia drug (OR = 1.48, 95% CI = 1.06 to 2.06, I2 = 94.8%, P < .001), surgical type (OR = 0.66, 95% CI = 0.49 to 0.9, I2 = 77.9%, P = .004) were statistically associated with postoperative thirst. CONCLUSIONS: Our study shows a high prevalence of postoperative thirst. Sex, anesthesia drug, and surgical type are risk factors that influence postoperative thirst. Nurses and other health care professionals should routinely assess the postoperative thirst of patients and perform targeted interventions to alleviate their distressing symptoms and improve the quality of care.

[The Comparative Effectiveness of Using Cold Water Oral Spray and Cold Saline Oral Spray for Thirst Relief in Patients With Endotracheal Intubation in the Intensive Care Unit].

BACKGROUND: Thirst is a common symptom among patients with endotracheal intubation in the intensive care unit (ICU), with an estimated prevalence of 88%. PURPOSE: This study was designed to compare the effectiveness of cold saline spray and cold water spray in alleviating thirst, and to explore the maintenance and sustained effects of both groups in relieving thirst among patients with endotracheal intubation in the ICU. METHODS: Patients with indwelling tracheal tubes in the medical ICU were recruited from one medical center in northern Taiwan and randomly assigned to either the cold saline (n = 18) or cold water (n = 18) group. The cold saline group received three rounds of cold saline spray at a temperature of 2°C - 8°C. Each round consisted of 10 sprays directed toward each of the four surfaces of the oral cavity followed by a 5-minute wait period. This process was repeated three times, with 30-minute intervals between interventions. The cold water group received the same intervention steps using a cold water spray at 2°C - 8°C. Thirst intensity was measured using a numeric rating scale before and after each of the three interventions in both groups. Demographic and relevant physiological data were collected on the participants by reviewing their medical records. RESULTS: Both of the interventions were found to effectively alleviate thirst intensity, with no significant difference between the two groups in terms of thirst intensity reduction after each intervention detected. Only the cold water spray had a maintenance effect, while the two groups had a continuous sustained effect in alleviating thirst intensity. CONCLUSIONS: Both of the interventions effectively alleviated thirst, and the cold water spray had both maintenance and sustained effects in alleviating thirst intensity. Based on the results, the cold water spray method may be considered as the priority treatment for thirst alleviation by healthcare providers in the clinical management of patients with tracheal intubation.

Behavioral responses of free-flying Drosophila melanogaster to shiny, reflecting surfaces.

Active locomotion plays an important role in the life of many animals, permitting them to explore the environment, find vital resources, and escape predators. Most insect species rely on a combination of visual cues such as celestial bodies, landmarks, or linearly polarized light to navigate or orient themselves in their surroundings. In nature, linearly polarized light can arise either from atmospheric scattering or from reflections off shiny non-metallic surfaces like water. Multiple reports have described different behavioral responses of various insects to such shiny surfaces. Our goal was to test whether free-flying Drosophila melanogaster, a molecular genetic model organism and behavioral generalist, also manifests specific behavioral responses when confronted with such polarized reflections. Fruit flies were placed in a custom-built arena with controlled environmental parameters (temperature, humidity, and light intensity). Flight detections and landings were quantified for three different stimuli: a diffusely reflecting matt plate, a small patch of shiny acetate film, and real water. We compared hydrated and dehydrated fly populations, since the state of hydration may change the motivation of flies to seek or avoid water. Our analysis reveals for the first time that flying fruit flies indeed use vision to avoid flying over shiny surfaces.

Vaptans or voluntary increased hydration to protect the kidney: how do they compare?

The adverse effects of vasopressin (AVP) in diverse forms of chronic kidney disease have been well described. They depend on the antidiuretic action of AVP mediated by V2 receptors (V2R). Tolvaptan, a selective V2R antagonist, is now largely used for the treatment of patients with autosomal dominant polycystic kidney disease. Another way to reduce the adverse effects of AVP is to reduce endogenous AVP secretion by a voluntary increase in fluid intake. These two approaches differ in several ways, including the level of thirst and AVP. With voluntary increased drinking, plasma osmolality will decline and so will AVP secretion. Thus, not only will V2R-mediated effects be reduced, but also those mediated by V1a and V1b receptors (V1aR and V1bR). In contrast, selective V2R antagonism will induce a loss of fluid that will stimulate AVP secretion and thus increase AVP's influence on V1a and V1b receptors. V1aR is expressed in the luminal side of the collecting duct (CD) and in inner medullary interstitial cells, and their activation induces the production of prostaglandins, mostly prostaglandin E2 (PGE2). Intrarenal PGE2 has been shown to reduce sodium and water reabsorption in the CD and increase blood flow in the renal medulla, both effects contributing to increase sodium and water excretion and reduce urine-concentrating activity. Conversely, non-steroidal anti-inflammatory drugs have been shown to induce significant water and sodium retention and potentiate the antidiuretic effects of AVP. Thus, during V2R antagonism, V1aR-mediated actions may be responsible for part of the diuresis observed with this drug. These V1aR-dependent effects do not take place with a voluntary increase in fluid intake. In summary, while both strategies may have beneficial effects, the information reviewed here leads us to assume that pharmacological V2R antagonism, with resulting stimulation of V1aR and increased PGE2 production, may provide greater benefit than voluntary high water intake. The influence of tolvaptan on the PGE2 excretion rate and the possibility to use somewhat lower tolvaptan doses than presently prescribed remain to be evaluated.

Effects of a low carbohydrate diet on heart failure symptoms and quality of life in patients with diabetic cardiomyopathy: A randomised controlled trial pilot study.

BACKGROUND AND AIMS: Heart failure, insulin resistance and/or type 2 diabetes mellitus coexist in the syndrome that is diabetic cardiomyopathy. Patients with diabetic cardiomyopathy experience high symptom burden and poor quality of life. We tested the hypothesis that a low carbohydrate diet improves heart failure symptoms and quality of life in patients with diabetic cardiomyopathy. METHODS AND RESULTS: We conducted a 16-week randomised controlled pilot trial comparing the effects of a low carbohydrate diet (LC) to usual care (UC) in 17 adult patients with diabetic cardiomyopathy. New York Heart Association classification, weight, thirst distress and quality of life scores as well as blood pressure and biochemical data were assessed at baseline and at 16 weeks. Thirteen (n = 8 LC; n = 5 UC) patients completed the trial. The low carbohydrate diet induced significant weight loss in completers (p = 0.004). There was a large between-group difference in systolic blood pressure at the end of the study (Hedges's g 0.99[-014,2.08]). There were no significant differences in thirst or quality of life between groups. CONCLUSION: This is the first clinical trial utilising the low carbohydrate dietary approach in patients with diabetic cardiomyopathy in an outpatient setting. A low carbohydrate diet can lead to significant weight loss in patients with diabetic cardiomyopathy. Future clinical trials with larger samples and that focus on fluid and sodium requirements of patients with diabetic cardiomyopathy who engage in a low carbohydrate diet are warranted. CLINICAL TRIAL REGISTRATION NUMBER: Australian New Zealand Clinical Trial Registry (ANZCTR): ACTRN12620001278921. DATE OF REGISTRATION: 26th November 2020.

Thirst intensity survey in ADPKD patients.

INTRODUCTION: With increased fluid intake and tolvaptan treatment, the growth rate of cysts can be theoretically decelerated in autosomal polycystic kidney disease. In this prospective study, it was planned to evaluate thirst sensation in these patients and the parameters affecting its intensity. METHODS: Forty-one ADPKD patients on tolvaptan and 40 ADPKD patients not on tolvaptan as the control group were evaluated for thirst distress sensation and intensity. The feeling of thirst and the discomfort caused by excessive fluid intake was assessed with Thirst Distress Scale-HF 12 questions (60/12). Thirst intensity was evaluated with a 100 mm visual scale. RESULTS: Of the whole group, 35.8% (29) were males, and 64.2% (52) were females. The mean age of the tolvaptan group was 39.17 ± 9.35 years and for the control group, it was 41.95 ± 12.29 years. There was a negative correlation between the thirst distress score of the patients and an increase in creatinine level after a year of tolvaptan treatment (r = - 0.335, p = 0.035). The patients not taking thiazide had higher thirst intensity scores (p = 0.004). There was no impact of tolvaptan dosage, total kidney volume, serum sodium, urinary osmolarity or eGFR on thirst distress and thirst intensity scores. DISCUSSION/CONCLUSION: Only thiazide co-treatment had a positive impact on thirst distress and intensity when given tolvaptan. Thirst Distress Scale for ADPKD patients can be used to classify patients before and during tolvaptan treatment.

Subjective Thirst in Relation to Interdialytic Weight Gain: A Systematic Review of Observational Studies.

INTRODUCTION: Hemodialysis (HD) patients are often prescribed salt and fluid-restricted diets to reduce their interdialytic weight gain (IDWG) and prevent chronic volume overload and hypertension. However, adherence to fluid restrictions is poor, which may be due to HD patients' excessive thirst. The purpose of the review is to explore the association between HD patients' subjective thirst and IDWG, which may inform strategies to manage chronic volume overload. METHODS: We conducted the literature search in Web of Science, Cumulative Index to Nursing and Allied Health Literature, PubMed, and the Cochrane Library, until February 25, 2019. Studies performing statistical tests to assess the association between patients' subjective thirst and IDWG were included. RESULTS: A total of eighteen studies were included in the systematic review, which measured the relationship between patients' subjective thirst and IDWG. Among them, 14 studies found that different domains of thirst and different units of IDWG are positively associated. Therefore, there is a positive association between the patients' subjective thirst and IDWG. However, the findings should be interpreted cautiously as there was variability in thirst and IDWG measurement techniques, which might influence the estimated relationship in these studies. DISCUSSION/CONCLUSION: These data suggest that strategies are needed to reduce thirst to control IDWG in HD patients.

Disinhibition augments thirst perception from two dehydrating stimuli in men.

Physiological systems controlling water and energy ingestion are coordinated. Whether maladaptive eating behavior and appetite for water are linked is unknown. Thus, we sought to investigate the association between maladaptive eating and both thirst and water drinking behavior with two dehydrating conditions. Twenty-two lean men and 20 men with obesity (mean age 32.3 ± 8.4 years and 30.0 ± 11.1 years, respectively) completed the Three-Factor Eating Questionnaire (TFEQ) and Gormally Binge Eating Scale. On separate days, volunteers were dehydrated by a 2-h hypertonic saline infusion and a 24-h water deprivation, and thirst was measured on a 100-mm visual analogue scale (VAS) during each procedure. After each dehydrating condition, ad libitum water intake was measured. In the saline infusion, higher Disinhibition on the TFEQ was associated with thirst in the lean group (ß = 4.2 mm VAS, p = 0.03) but not in the group with obesity (p = 0.51). In the water-deprivation condition, higher Disinhibition was also associated with thirst in the lean group (ß = 5.6 mm VAS, p = 0.01) with the strength of relationship being 3.5-fold stronger than that observed in the group with obesity (ß = 1.6 mm VAS, p = 0.0003). Hunger, Restraint, and binge-eating scores were not associated with thirst in either dehydrating condition (all p > 0.05). Maladaptive eating behaviors were not associated with ad libitum water intake (all p > 0.05). Disinhibition is associated with higher thirst perception in healthy weight individuals and may be attenuated in obesity. The characteristics of disinhibition which typically includes a heightened readiness to eat, may reflect a more general phenotype that also reflects a readiness to drink.

Regional brain responses associated with using imagination to evoke and satiate thirst.

In response to dehydration, humans experience thirst. This subjective state is fundamental to survival as it motivates drinking, which subsequently corrects the fluid deficit. To elicit thirst, previous studies have manipulated blood chemistry to produce a physiological thirst stimulus. In the present study, we investigated whether a physiological stimulus is indeed required for thirst to be experienced. Functional MRI (fMRI) was used to scan fully hydrated participants while they imagined a state of intense thirst and while they imagined drinking to satiate thirst. Subjective ratings of thirst were significantly higher for imagining thirst compared with imagining drinking or baseline, revealing a successful dissociation of thirst from underlying physiology. The imagine thirst condition activated brain regions similar to those reported in previous studies of physiologically evoked thirst, including the anterior midcingulate cortex (aMCC), anterior insula, precentral gyrus, inferior frontal gyrus, middle frontal gyrus, and operculum, indicating a similar neural network underlies both imagined thirst and physiologically evoked thirst. Analogous brain regions were also activated during imagined drinking, suggesting the neural representation of thirst contains a drinking-related component. Finally, the aMCC showed an increase in functional connectivity with the insula during imagined thirst relative to imagined drinking, implying functional connectivity between these two regions is needed before thirst can be experienced. As a result of these findings, this study provides important insight into how the neural representation of subjective thirst is generated and how it subsequently motivates drinking behavior.

Ethical challenges around thirst in end-of-life care -experiences of palliative care physicians.

BACKGROUND: Thirst and dry mouth are common symptoms in terminally ill patients. In their day-to-day practice, palliative care physicians regularly encounter ethical dilemmas, especially regarding artificial hydration. Few studies have focused on thirst and the ethical dilemmas palliative care physicians encounter in relation to this, leading to a knowledge gap in this area. AIM: The aim of this study was to explore palliative care physicians' experiences of ethical challenges in relation to thirst in terminally ill patients. METHODS: A qualitative interview study with an inductive approach was conducted. Sixteen physicians working in four different specialised palliative care units and one geriatric care unit in different hospitals in Sweden were interviewed. The interviews were transcribed verbatim and analysed with a reflexive thematic analysis. RESULTS: When presented with an ethical challenge relating to thirst, physicians attempted to balance benefits and harms while emphasizing respect for the patient's autonomy. The ethical challenges in this study were: Starting, continuing or discontinuing drips; lack of evidence and traditions create doubt; and lack of interest and time may result in patient suffering. CONCLUSIONS: All physicians in this study reported that "Starting, continuing or discontinuing drips" was the main ethical challenge they encountered, where some were so accustomed to the decision that they had a standard answer ready to offer patients and families. Physicians reported that drips were a symbol of thirst quenching, life and survival but were not necessary in end-of-life care. Others questioned the traditions regarding thirst and emphasised drips in particular.

The responsibility to quench thirst by providing drinks when a relative is dying spouses' experience in specialist palliative home care.

BACKGROUND: Thirst and dry mouth are common symptoms in terminally ill patients. It is known that family members usually request drips for their dying relative. Few studies have focused on thirst in terminally ill patients and their spouses' experience of this, leading to a knowledge gap in this area. AIM: The aim of this study was to explore spouses' experiences of observing and managing thirst in a dying relative admitted to specialist palliative home care. METHODS: A qualitative interview study with an inductive approach was conducted. Eighteen spouses caring for their husband or wife admitted to specialist palliative home care in different hospitals in Sweden were interviewed. The interviews were transcribed verbatim and analysed with a reflexive thematic analysis. RESULTS: Three main themes emerged regarding spouses' experiences of patients' thirst: Knowledge and views of thirst; Control of fluid intake provides vital information; and Taking charge of their drinking is a life and death responsibility. CONCLUSIONS: Spouses experience a responsibility to serve the dying person with fluids so that they will not get thirsty. It is so obvious and commonplace to them. To be able to fulfil this responsibility, they need to keep track of the patient's fluid intake and know what quenches thirst. There is a need for research in this area to assist carers and patients in identifying which drinks best quench the patient's thirst. Interventions are also needed to help provide/make available knowledge on suitable thirst-quenching drinks.

Human thirst behavior requires transformation of sensory inputs by intrinsic brain networks.

BACKGROUND: To survive and thrive, many animals, including humans, have evolved goal-directed behaviors that can respond to specific physiological needs. An example is thirst, where the physiological need to maintain water balance drives the behavioral basic instinct to drink. Determining the neural basis of such behaviors, including thirst response, can provide insights into the way brain-wide systems transform sensory inputs into behavioral outputs. However, the neural basis underlying this spontaneous behavior remains unclear. Here, we provide a model of the neural basis of human thirst behavior. RESULTS: We used fMRI, coupled with functional connectivity analysis and serial-multiple mediation analysis, we found that the physiological need for water is first detected by the median preoptic nucleus (MnPO), which then regulates the intention of drinking via serial large-scale spontaneous thought-related intrinsic network interactions that include the default mode network, salience network, and frontal-parietal control network. CONCLUSIONS: Our study demonstrates that the transformation in humans of sensory inputs for a single physiological need, such as to maintain water balance, requires large-scale intrinsic brain networks to transform this input into a spontaneous human behavioral response.