Psychogenic fever, functional fever, or psychogenic hyperthermia?

Neural cell-types and circuits linking thermoregulation and social behavior

Understanding how social and affective behavioral states are controlled by neural circuits is a fundamental challenge in neurobiology. Despite increasing understanding of central circuits governing prosocial and agonistic interactions, how bodily autonomic processes regulate these behaviors is less resolved. Thermoregulation is vital for maintaining homeostasis, but also associated with cognitive, physical, affective, and behavioral states. Here, we posit that adjusting body temperature may be integral to the appropriate expression of social behavior and argue that understanding neural links between behavior and thermoregulation is timely. First, changes in behavioral states-including social interaction-often accompany changes in body temperature. Second, recent work has uncovered neural populations controlling both thermoregulatory and social behavioral pathways. We identify additional neural populations that, in separate studies, control social behavior and thermoregulation, and highlight their relevance to human and animal studies. Third, dysregulation of body temperature is linked to human neuropsychiatric disorders. Although body temperature is a "hidden state" in many neurobiological studies, it likely plays an underappreciated role in regulating social and affective states.

Altered skeletal muscle sarco-endoplasmic reticulum Ca2+-ATPase calcium transport efficiency after a thermogenic stimulus

Exposure to predator threat induces a rapid and robust increase in skeletal muscle thermogenesis in rats. The central nervous system relays threat information to skeletal muscle through activation of the sympathetic nervous system, but muscle mechanisms mediating this thermogenesis remain unidentified. Given the relevance of sarcolipin-mediated futile calcium cycling through the sarco-endoplasmic reticulum Ca2+-ATPase (SERCA) pump to mammalian muscle nonshivering thermogenesis, we hypothesized that this plays a role in contextually induced muscle thermogenesis as well. This was assessed by measuring enzymatic activity of SERCA and sarcoplasmic reticulum Ca2+ transport, where the apparent coupling ratio (Ca2+ uptake rate divided by ATPase activity rate at a standard Ca2+ concentration) was predicted to decrease in association with muscle thermogenesis. Sprague-Dawley rats exposed to predator (ferret) odor (PO) showed a rapid decrease in the apparent coupling ratio in the soleus muscle, indicating SERCA uncoupling compared with control-odor-exposed rats. A rat model of high aerobic fitness and elevated muscle thermogenesis also demonstrated soleus muscle SERCA uncoupling relative to their obesity-prone, low-fitness counterparts. Both the high- and low-aerobic fitness rats showed soleus SERCA uncoupling with exposure to PO. Finally, no increase in sarcolipin expression in soleus muscle was detected with PO exposure. This dataset implicates muscle uncoupling of SERCA Ca2+ transport and ATP hydrolysis, likely through altered SERCA or sarcolipin function outside of translational regulation, as one contributor to the muscle thermogenesis provoked by exposure to predator threat. These data support the involvement of SERCA uncoupling in both muscle thermogenic induction and enhanced aerobic capacity.

Psychogenic fever and postural tachycardia syndrome among school-aged children and adolescents with fever of unknown origin

Background

Although fever is a common symptom in pediatric practice, its origin is often unknown in pediatric patients. Psychogenic fever is a stress-related, psychosomatic disease observed especially in young women. This study aimed to estimate the prevalence of psychogenic fever in pediatric patients with fever of unknown origin by surveying the medical records of school-aged children and adolescents.

Methods

The study subjects included 47 patients aged 6–15 years who visited the Department of Pediatrics in Kansai Medical University Medical Center between January 2006 and December 2020 with fever of unknown origin. Data on age, sex, final estimated diagnosis, and comorbid psychosocial issues were collected from the medical records.

Results

The study was composed of 47 patients, including 22 male and 25 female patients (male/female ratio, 1:1.36). The mean age was 10.1 (standard deviation, 2.4) years for boys and 11.6 (standard deviation, 2.7) years for girls (p = .047). The final estimated diagnoses were psychogenic fever, physical disorder, infection of unknown origin, and miscellaneous in 18, 12, 12, and 5 patients, respectively. The most common comorbidity in these pediatric patients with psychogenic fever was postural tachycardia syndrome.

Conclusion

Psychogenic fever was a common cause of fever of unknown origin in pediatric patients, and postural tachycardia was prevalent among children with psychogenic fever. Enhanced sympathetic response to stress might play an important role in both psychogenic fever and postural tachycardia.

Postoperative hyperthermia-induced multiple organ failure in a child with Down syndrome: a case report

Background

Psychological stress has been reported to cause hyperthermia. Persistent excessive hyperthermia can, in turn, cause hypercytokinemia and organ damage. We report a case of postoperative severe hyperthermia leading to a systemic inflammatory response and multiple organ failure in a child with Down syndrome.

Case presentation

A 10-month-old native Japanese boy with Down syndrome and Hirschsprung’s disease is described. Newborn screening showed congenital hypothyroidism and a ventricular septal defect, but these conditions were stable upon administration of levothyroxine and furosemide. His development was equivalent to that of a child with Down syndrome. He developed a noninfectious high fever twice after preoperative preparations at age 8 months and again at 9 months. He was readmitted to hospital at age 10 months to undergo the Soave procedure to correct Hirschsprung’s disease. However, he contracted a fever immediately after the surgical procedure. Hyperthermia (42 °C) was refractory to acetaminophen treatment and deteriorated to multiple organ failure due to hypercytokinemia, with increased serum levels of interleukin-6 (44.6 pg/mL) and interleukin-10 (1010 pg/mL). He died on postoperative day 2 with hypoxemia, respiratory/metabolic acidosis, increased serum levels of transaminases, reduced coagulation, and pancytopenia. Various infectious and noninfectious causes of hyperthermia could not be identified clearly by culture or blood tests.

Conclusions

We speculated that the proximate cause of the fever was psychological stress, because he suffered repeated episodes of hyperthermia after the invasive procedure. Hyperthermia, together with the immune-system disorders associated with Down syndrome, may have induced hypercytokinemia and multiple organ failure. This rare case of noninfectious postoperative hyperthermia leading to multiple organ failure may help to shed further light on the currently unclear pathogenic mechanism of hyperthermia and associated multiple organ failure during the perioperative period in children.

Infrared Thermography Reveals Sex-Specific Responses to Stress in Mice

Psychogenic hyperthermia is a stress-related condition reported mostly in women. Neuroendocrine responses to stress in females differ from those in males, and these differences cannot be explained solely based on hypothalamic-pituitary-adrenal (HPA) axis activity. Here, we used infrared (IR) thermographic imaging to record changes in cutaneous temperature following two types of stressful experiences in female and male mice. Mice were exposed to either single-session restraint stress or vertical exploration (rearing) deprivation and were monitored for exploratory activity and IR surface thermal changes. Females displayed higher rearing activity than males during the dark phase of the light cycle. Both sexes showed similar plasma corticosterone (CORT) responses after a challenge with restraint and rearing deprivation. However, only females responded to rearing deprivation with increased cutaneous temperature in the head and back, and a reduced thermal response in the tail. Circulating CORT levels were not correlated with the thermal variations. These findings, for the first time, provide evidence for sex-specific cutaneous thermal responses to short-term stress in mice following transient vertical-activity deprivation that may mimic clinical psychogenic hyperthermia.

[Informations on psychotropics and their adaptations for patients suffering from mental disorders in France during the SARS-CoV-2 epidemic]

The 2019-20 coronavirus pandemic (SARS-CoV-2; severe acute respiratory syndrome coronavirus 2) has dramatic consequences on populations in terms of morbidity and mortality and in social terms, the general confinement of almost half of the world's population being a situation unprecedented in history, which is difficult today to measure the impact at the individual and collective levels. More specifically, it affects people with various risk factors, which are more frequent in patients suffering from psychiatric disorders. Psychiatrists need to know: (i) how to identify, the risks associated with the prescription of psychotropic drugs and which can prove to be counterproductive in their association with COVID-19 (coronavirus disease 2019), (ii) how to assess in terms of benefit/risk ratio, the implication of any hasty and brutal modification on psychotropic drugs that can induce confusion for a differential diagnosis with the evolution of COVID-19. We carried out a review of the literature aimed at assessing the specific benefit/risk ratio of psychotropic treatments in patients suffering from COVID-19. Clinically, symptoms suggestive of COVID-19 (fever, cough, dyspnea, digestive signs) can be caused by various psychotropic drugs and require vigilance to avoid false negatives and false positives. In infected patients, psychotropic drugs should be used with caution, especially in the elderly, considering the pulmonary risk. Lithium and Clozapine, which are the reference drugs in bipolar disorder and resistant schizophrenia, warrant specific attention. For these two treatments the possibility of a reduction in the dosage - in case of minimal infectious signs and in a situation, which does not allow rapid control - should ideally be considered taking into account the clinical response (even biological; plasma concentrations) observed in the face of previous dose reductions. Tobacco is well identified for its effects as an inducer of CYP1A2 enzyme. In a COVID+ patient, the consequences of an abrupt cessation of smoking, particularly related with the appearance of respiratory symptoms (cough, dyspnea), must therefore be anticipated for patients receiving psychotropics metabolized by CYP1A2. Plasma concentrations of these drugs are expected to decrease and can be related to an increase risk of relapse. The symptomatic treatments used in COVID-19 have frequent interactions with the most used psychotropics. If there is no curative treatment for infection to SARS-CoV-2, the interactions of the various molecules currently tested with several classes of psychotropic drugs (antidepressants, antipsychotics) are important to consider because of the risk of changes in cardiac conduction. Specific knowledge on COVID-19 remains poor today, but we must recommend rigor in this context in the use of psychotropic drugs, to avoid adding, in patients suffering from psychiatric disorders, potentially vulnerable in the epidemic context, an iatrogenic risk or loss of efficiency.