Heat intolerance induced by antidepressants

A reappraisal of the role of fever in the occurrence of neurological sequelae following lithium intoxication: a systematic review

INTRODUCTION

We aimed to review cases of Syndrome of Irreversible Lithium-Effectuated Neurotoxicity (SILENT) characterized by neurological sequelae following acute lithium toxicity and to explore whether cerebellar sequelae are more frequent in cases presenting with fever and/or infection.

AREAS COVERED

Case reports were identified from: (i) 6 reviews published up to 2005; (ii) MEDLINE, Web of Sciences, Cochrane Library and PsycINFO search.

EXPERT OPINION

We identified 123 SILENT cases published from 1965 to 2019, in which cerebellar sequelae were observed in an overwhelming proportion (79%). SILENT may occur at any time during lithium treatment. This complication is most frequently observed during routine lithium treatment, with fewer than 10% of cases occurring after accidental or intentional overdoses. SILENT may occur even when lithium plasma levels are within the therapeutic range: 63% of cases had lithium plasma level <2.5 mEq/l (low/mild toxicity). Fever and/or infection were reported in nearly half of the patients (48%). The likelihood of presenting with cerebellar vs. other neurological sequelae was independently increased by elevated plasma lithium level (≥ 2.5 mEq/l) and by a history of fever and/or infection. Lithium users should be warned of the need to consult in case of fever to adjust their lithium dosage.

Overtraining Syndrome as a Complex Systems Phenomenon

The phenomenon of reduced athletic performance following sustained, intense training (Overtraining Syndrome, and OTS) was first recognized more than 90 years ago. Although hundreds of scientific publications have focused on OTS, a definitive diagnosis, reliable biomarkers, and effective treatments remain unknown. The present review considers existing models of OTS, acknowledges the individualized and sport-specific nature of signs/symptoms, describes potential interacting predisposing factors, and proposes that OTS will be most effectively characterized and evaluated via the underlying complex biological systems. Complex systems in nature are not aptly characterized or successfully analyzed using the classic scientific method (i.e., simplifying complex problems into single variables in a search for cause-and-effect) because they result from myriad (often non-linear) concomitant interactions of multiple determinants. Thus, this review 1) proposes that OTS be viewed from the perspectives of complex systems and network physiology, 2) advocates for and recommends that techniques such as trans-omic analyses and machine learning be widely employed, and 3) proposes evidence-based areas for future OTS investigations, including concomitant multi-domain analyses incorporating brain neural networks, dysfunction of hypothalamic-pituitary-adrenal responses to training stress, the intestinal microbiota, immune factors, and low energy availability. Such an inclusive and modern approach will measurably help in prevention and management of OTS.

Factors affecting heat-related diseases in outdoor workers exposed to extreme heat

Background

The objectives of the present study are to: (i) evaluate the effect of environmental and metabolic heat on heat-related illnesses in outdoor workers; and (ii) evaluate the effect of personal factors, including heat acclimation, on the risk of heat-related illnesses in outdoor workers.

Methods

We identified 47 cases of illnesses from exposure to environmental heat in outdoor workers in Korea from 2010 to 2014, based on review of workers’ compensation data. We also obtained the information on location, time, and work environment of each heat-related illness.

Results

Our major results are that 29 cases (61.7%) occurred during a heat wave. Forty five cases (95.7%) occurred when the maximum estimated WBGT (WBGTmax) was equal to or greater than the case specific threshold value which was determined by acclimatization and metabolic rate. Twenty two cases (46.8%) were not acclimated to the heat. Thirty-seven cases (78.7%) occurred after tropical night (temperature above 25 °C), during which many people may find it hard to sleep.

Conclusion

Personal risk factors such as heat acclimation as well as environmental factors and high metabolic rate during work are the major determinants of heat-related illnesses.

Limitations to Thermoregulation and Acclimatization Challenge Human Adaptation to Global Warming

Human thermoregulation and acclimatization are core components of the human coping mechanism for withstanding variations in environmental heat exposure. Amidst growing recognition that curtailing global warming to less than two degrees is becoming increasing improbable, human survival will require increasing reliance on these mechanisms. The projected several fold increase in extreme heat events suggests we need to recalibrate health protection policies and ratchet up adaptation efforts. Climate researchers, epidemiologists, and policy makers engaged in climate change adaptation and health protection are not commonly drawn from heat physiology backgrounds. Injecting a scholarly consideration of physiological limitations to human heat tolerance into the adaptation and policy literature allows for a broader understanding of heat health risks to support effective human adaptation and adaptation planning. This paper details the physiological and external environmental factors that determine human thermoregulation and acclimatization. We present a model to illustrate the interrelationship between elements that modulate the physiological process of thermoregulation. Limitations inherent in these processes, and the constraints imposed by differing exposure levels, and thermal comfort seeking on achieving acclimatization, are then described. Combined, these limitations will restrict the likely contribution that acclimatization can play in future human adaptation to global warming. We postulate that behavioral and technological adaptations will need to become the dominant means for human individual and societal adaptations as global warming progresses.

Climate change: challenges and opportunities for global health

IMPORTANCE

Health is inextricably linked to climate change. It is important for clinicians to understand this relationship in order to discuss associated health risks with their patients and to inform public policy.

OBJECTIVES

To provide new US-based temperature projections from downscaled climate modeling and to review recent studies on health risks related to climate change and the cobenefits of efforts to mitigate greenhouse gas emissions.

DATA SOURCES, STUDY SELECTION, AND DATA SYNTHESIS

We searched PubMed and Google Scholar from 2009 to 2014 for articles related to climate change and health, focused on governmental reports, predictive models, and empirical epidemiological studies. Of the more than 250 abstracts reviewed, 56 articles were selected. In addition, we analyzed climate data averaged over 13 climate models and based future projections on downscaled probability distributions of the daily maximum temperature for 2046-2065. We also compared maximum daily 8-hour average ozone with air temperature data taken from the National Oceanic and Atmospheric Administration, National Climate Data Center.

RESULTS

By 2050, many US cities may experience more frequent extreme heat days. For example, New York and Milwaukee may have 3 times their current average number of days hotter than 32°C (90°F). High temperatures are also strongly associated with ozone exceedance days, for example, in Chicago, Illinois. The adverse health aspects related to climate change may include heat-related disorders, such as heat stress and economic consequences of reduced work capacity; respiratory disorders, including those exacerbated by air pollution and aeroallergens, such as asthma; infectious diseases, including vectorborne diseases and waterborne diseases, such as childhood gastrointestinal diseases; food insecurity, including reduced crop yields and an increase in plant diseases; and mental health disorders, such as posttraumatic stress disorder and depression, that are associated with natural disasters. Substantial health and economic cobenefits could be associated with reductions in fossil fuel combustion. For example, greenhouse gas emission policies may yield net economic benefit, with health benefits from air quality improvements potentially offsetting the cost of US and international carbon policies.

CONCLUSIONS AND RELEVANCE

Evidence over the past 20 years indicates that climate change can be associated with adverse health outcomes. Health care professionals have an important role in understanding and communicating the related potential health concerns and the cobenefits from policies to reduce greenhouse gas emissions.

Self-reported benefits and risks of yoga in individuals with bipolar disorder

BACKGROUND

Although hatha yoga has frequently been recommended for patients with bipolar disorder (BD) and there is preliminary evidence that it alleviates depression, there are no published data on the benefits-and potential risks-of yoga for patients with BD. Thus, the goal of this study was to assess the risks and benefits of yoga in individuals with BD.

METHODS

We recruited self-identified yoga practitioners with BD (N=109) to complete an Internet survey that included measures of demographic and clinical information and open-ended questions about yoga practice and the impact of yoga.

RESULTS

86 respondents provided sufficient information for analysis, 70 of whom met positive screening criteria for a lifetime history of mania or hypomania. The most common styles of yoga preferred were hatha and vinyasa. When asked what impact yoga had on their life, participants responded most commonly with positive emotional effects, particularly reduced anxiety, positive cognitive effects (e.g., acceptance, focus, or "a break from my thoughts"), or positive physical effects (e.g., weight loss, increased energy). Some respondents considered yoga to be significantly life changing. The most common negative effect of yoga was physical injury or pain. Five respondents gave examples of specific instances or a yoga practice that they believed increased agitation or manic symptoms; five respondents gave examples of times that yoga increased depression or lethargy.

CONCLUSIONS

Many individuals who self-identify as having BD believe that yoga has benefits for mental health. However, yoga is not without potential risks. It is possible that yoga could serve as a useful adjunctive treatment for BD.

Thermal dehydration-induced thirst in lithium-treated rats

Lithium is used as the primary treatment for bipolar disorder but has the common side effects of diuresis and thirst. In the present study, the effects of lithium on water balance responses of male Sprague-Dawley rats to thermal dehydration were examined. Rats ate either unadulterated food or food containing 2 g/kg lithium carbonate for 10 days. Then the control and lithium-treated rats were exposed to either 25 or 37.5 degrees C without food or water for 4 h. The rats were then allowed access to water for 3 h at 25 degrees C or were anesthetized and blood samples were taken. Lithium treatment caused an initial decrease in food intake, a decrease in body weight, and an increase in urine output. Heat exposure caused similar increases in evaporative water loss in control and lithium-treated rats. Heat exposure led to changes in blood indicators of body water status indicative of dehydration, whereas lithium had no effects on blood indicators of body water status. Water intake was increased by both heat exposure and by lithium treatment with the lithium-treated rats being more responsive to the thirst-inducing effects of thermal dehydration. Lithium treatment does not appear to impair water balance responses to heat exposure.

Ambient temperature influences core body temperature response in rat lines bred for differences in sensitivity to 8-hydroxy-dipropylaminotetralin

Agonist-induced decrease in core body temperature has commonly been used as a measure of serotonin1A (5-HT(1A)) receptor sensitivity in mood disorder. The thermoregulatory basis for 5-HT(1A) receptor agonist-induced temperature responses in humans and rats remains unclear. Therefore, the influence of ambient temperature on 5-HT(1A) receptor-mediated decreases in core body temperature were measured in rat lines bred for high (HDS) or low (LDS) sensitivity to the selective 5-HT(1A) receptor agonist 8-hydroxy-dipropylaminotetralin (8-OH-DPAT). HDS and LDS rats were injected with either saline, 0.25 or 0.50 mg/kg 8-OH-DPAT at ambient temperatures of 10.5, 24, 30, or 37.5 degrees C, and core temperature was measured by radiotelemetry. For both lines, the thermic response to acute 8-OH-DPAT was greatest at 10.5 degrees C and decreased in magnitude as ambient temperature increased to 30 degrees C, consistent with hypothermia. HDS rats displayed a greater hypothermic response than LDS rats at 10.5, 24, and 30 degrees C. At 37.5 degrees C, LDS rats showed a lethal elevation of temperature in response to 0.50 mg/kg 8-OH-DPAT. All thermic responses to 8-OH-DPAT, including the lethality, were effectively blocked by pretreatment with the 5-HT(1A) receptor antagonist WAY100635, suggesting line differences in thermoregulatory circuits that are influenced by 5-HT(1A) receptor activation. Following repeated injection of 8-OH-DPAT, the magnitude of the hypothermic response decreased in both lines at 10.5 degrees C, but increased in HDS rats treated with 0.50 mg/kg 8-OH-DPAT at 30 and 37.5 degrees C. This pattern was reversed in HDS rats following 8-OH-DPAT challenge at 24 degrees C, suggesting that a compensatory thermoregulatory response accounts for changes in the hypothermic response to chronic 8-OH-DPAT.

Depression after stroke: a review of the evidence base to inform the development of an integrated care pathway. Part 2: Treatment alternatives

BACKGROUND

Depression is a common complication of stroke, leading to increased morbidity and mortality. It can impede the process of rehabilitation, and has been associated with poorer outcomes and increased length of stay in hospital. This systematic review was undertaken as a preliminary step to the development of an evidence-based integrated care pathway (ICP) for the management of post-stroke depression (PSD) in a rehabilitation setting, and is divided into two parts. In part 1 we reviewed the frequency of depression in stroke, its impact on functional recovery and the different methods for assessment.

AIMS AND OBJECTIVES

In part 2, we discuss the rationale for treatment of PSD, appraise the evidence for effectiveness of the different antidepressant drugs, and consider whether we can identify a recommended first-line treatment for use in our ICP.

METHODS

Data sources comprised a computer-aided search of published studies on depression in stroke and references to literature used in reviews.

MAIN FINDINGS

From the few controlled trials of anti-depressant therapy in PSD, both tricyclics and selective serotonin re-uptake inhibitors (SSRIs) appear to be effective, but the latter may be preferable in stroke because of their prompt action and better side-effect profiles. Within the group of SSRIs there is currently no direct evidence to guide the choice of agent. In the absence of firm guidance, sertraline was chosen on theoretical grounds as one of the most potent with minimal sedative effects and no reported interaction with warfarin. Citalopram may offer an appropriate second choice.

CONCLUSIONS

A suggested regimen for the use of sertraline in PSD was put forward. Development of an ICP may help to establish a more consistent approach to assessment and treatment of PSD, and form a basis for future comparison of different treatments as they become available.

The unknown mechanism of the overtraining syndrome: clues from depression and psychoneuroimmunology

When prolonged, excessive training stresses are applied concurrent with inadequate recovery, performance decrements and chronic maladaptations occur. Known as the overtraining syndrome (OTS), this complex condition afflicts a large percentage of athletes at least once during their careers. There is no objective biomarker for OTS and the underlying mechanism is unknown. However, it is not widely recognised that OTS and clinical depression [e.g. major depression (MD)] involve remarkably similar signs and symptoms, brain structures, neurotransmitters, endocrine pathways and immune responses. We propose that OTS and MD have similar aetiologies. Our examination of numerous shared characteristics offers insights into the mechanism of OTS and encourages testable experimental hypotheses. Novel recommendations are proposed for the treatment of overtrained athletes with antidepressant medications, and guidelines are provided for psychological counselling.

Impacts of climate and climate change on medications and human health

OBJECTIVE

To examine impacts of climate and climate change on medications and human health.

METHODS

Literature review and analysis of MIMS.

RESULTS

Changed climate associated with the enhanced Greenhouse Effect (e.g. increased temperature) may lead to medication-related health impacts through deterioration of storage conditions, increased heat stress from medication-induced heat intolerance, and by influencing pharmacokinetics. Increases in UV radiation from stratospheric ozone depletion may increase the significance of medications that can lead to an increased sensitivity to the damaging effects of UV radiation (i.e. photosensitivity).

CONCLUSIONS AND IMPLICATIONS

Raising awareness of the impacts of climate on medications, and of climate-related side-effects, among both health care professionals and the public, should modify behaviour and therefore reduce the risks of such adverse impacts.