Corneal temperature in schizophrenia patients

Abstract

Most data imply that dopaminergic transmission is essential for proper hypothalamic-mediated core temperature regulation. Altered central dopaminergic transmission is suggested to be involved in the pathophysiology of schizophrenia. Thus, hypothetically, schizophrenia patients might be at increased risk of developing thermoregulatory dysregulation manifested by alterations in core temperature, as well as in peripheral tissue, the temperature of which has been shown to correlate with core temperature (e.g. cornea). Previous small pilot studies of ours showed that schizophrenia patients may exhibit corneal temperature abnormalities. Hence, we assessed corneal temperature in a controlled sample of drug-free ( n =11) and medicated ( n =28) schizophrenia patients compared to healthy comparison subjects ( n =9), using a FLIR thermal imaging camera. Drug-free schizophrenia patients exhibited significantly higher corneal temperature compared to healthy subjects, typical antipsychotic drug (APD)-treated patients ( n =16) and atypical APD-treated patients ( n =12) (37.08+/-1.46 degrees C vs. 33.37+/-2.51 degrees C, 31.08+/-1.43 degrees C and 31.67+/-0.44 degrees C respectively, p <0.0001; p <0.001 vs. each group separately). The healthy comparison subjects and the atypical APD-treated patients exhibited comparable corneal temperatures and these two groups exhibited higher corneal temperatures compared to the typical APD-treated patients ( p <0.01 and p =0.051 respectively). In conclusion, this study indicates that drug-free schizophrenia patients exhibit substantially higher corneal temperature compared to healthy comparison subjects or medicated patients, and that APDs may decrease corneal temperature either to normal (atypical APD) or to subnormal (typical APD) values. The relevance of these phenomena to the pathophysiology of schizophrenia, the biological mechanism underlying drug-induced corneal temperature alterations, the possible role of temperature-lowering drugs (neuroleptics or non-neuroleptics) on schizophrenic psychosis as well as the role of corneal temperature as a tool to evaluate adherence to APD treatment merit further investigation via larger samples of both medicated and drug-free schizophrenia patients compared to matched controlled subjects.

Altered thermoregulation in ambulatory schizophrenia patients: A naturalistic study

“…Specifically, our findings imply that an increase in schizophrenia patients' core temperature may be associated with the presence of predominant ''positive'' signs/overt psychosis while decreased core temperature often reflects predominant ''negative'' symptoms of schizophrenia (Shiloh et al 2007 in press). Our findings also propose that APDs may directly affect thermoregulation, with preliminary data suggesting that second generation APDs (SGAs) may lower temperature to values comparable to those of healthy subjects while first generation APDs (FGAs) decrease temperature to subnormal values (Shiloh et al 2005).…”

“…Accrued data suggests that schizophrenia patients exhibit dysfunctional thermoregulation manifested by enhanced susceptibility to experience psychotic exacerbations during increased environmental temperature (Shiloh et al 2005), increased core temperature during exercise-induced heat stress (Hermesh et al 2000a;Shiloh et al 2001) and increased core/body temperature during acute psychotic exacerbations (Heh et al 1988;Maeir et al 1994;Shiloh et al 2003bShiloh et al , 2005. Moreover, our previous studies suggest that schizophrenia patients' mental status (as reflected by patients' Positive and Negative Syndrome Scale (PANSS) (Kay et al 1987) and Brief Psychiatric rating scale (BPRS) (Overall and Gorham 1961) scores) might correlate with their core/body temperature (Shiloh et al 2007 in press).…”

“…with predominant ''positive'' symptoms) can exhibit increased core temperature (Heh et al 1988;Shiloh et al 2000Shiloh et al , 2003b while APD-treated patients (Heh et al 1988;Harada et al 1994;Eikenboom et al 1997;Shiloh et al 2000Shiloh et al , 2003aShiloh et al ,b, 2005, patients in partial remission and/or patients with predominant ''negative'' symptomathology (Shiloh et al 2003b(Shiloh et al , 2007 in press) may have decreased core temperature. In standardized clinical settings, APDs have shown their capacity to lower core/body temperature of schizophrenia patients only to a certain extent and, in some cases, for a time-limited period (Shiloh et al 2000(Shiloh et al , 2005. Therefore, the group of Leumit Health Fund ambulatory schizophrenia patients may represent a community population in which a ''primary'' decreased core temperature (due, probably, to predominant ''negative'' symptomatology) over-dominates and masks the temperature lowering effects of APDs.…”

“…Consequently, both medicated and drug-free ambulatory patients may exhibit similar low oral temperatures. Moreover, although the temperature lowering capacity of APDs has been previously demonstrated (Yehuda 1977;Fjalland 1979;Heh et al 1988;Harada et al 1994;Maeir et al 1994;Eikenboom et al 1997;Schwaninger et al 1998;Shiloh et al 2000Shiloh et al , 2005, it is based, mainly, on anecdotal reports or small case-series studies while large-scale and standardized studies are still lacking. Thus, it could be that the inconsistencies between some of the previous findings (i.e.…”

Schizophrenia and Infections: The Eyes Have It

“…Shiloh et al 24 reported that the temperature of the cornea in drug-free individuals with schizophrenia is significantly higher than those on antipsychotic medication or normal controls. They also reported that the corneal temperature fluctuated with the patients' symptoms.…”