Corneal temperature in schizophrenia patients

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°C vs. 33.37±2.51°C, 31.08±1.43°C and 31.67±0.44°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.