Scientists have discovered the impact of manic episodes on skin temperature.

A new study has found that people with bipolar disorder experience significantly elevated skin temperature during manic episodes. This physiological marker, recorded using wearable devices, could be key to objectively monitoring mental health and early warning of relapses.

Bipolar disorder, which affects approximately 2.4 percent of the world's population, has long been a subjective diagnosis: doctors relied on patient surveys and clinical observations, making accurate diagnosis and monitoring difficult. However, a new study conducted by specialists at the Barcelona Clinic Hospital may change this approach. Scientists have found that during manic episodes, patients' skin temperature consistently increases by approximately 0.8 degrees Celsius compared to periods of stable mood or depression. This effect disappears completely after the condition returns to normal, indicating that it is directly related to mental status rather than to chronic bodily characteristics.

The study involved 139 adults, including 104 patients with bipolar disorder and 35 healthy controls. Participants wore a wrist-worn device for 48 hours that recorded skin temperature and physical activity levels. Patients with manic episodes showed an average daytime temperature of 33.61 degrees Celsius—significantly higher than the other groups. However, nighttime temperature maintained a normal circadian rhythm, and the amplitude of fluctuations did not change, suggesting a specific manic episode rather than a general thermoregulatory disorder.

Study author Diego Hidalgo-Mazzei explains that the increase in temperature may be related to increased mitochondrial activity, which generates more heat during manic episodes. An alternative hypothesis suggests disruptions in the hypothalamus and brainstem systems, which regulate both mood and body temperature. Interestingly, no significant changes in skin temperature were observed during depressive episodes, suggesting different mechanisms for these conditions.

Despite these findings, the researchers caution that skin temperature alone cannot serve as a sole diagnostic criterion—it is influenced by physical activity, the environment, medications, and individual characteristics. However, when combined with other biomarkers, such as heart rate variability and skin electrical activity, it could become part of a multimodal monitoring system. The scientists aim to develop a device that patients with bipolar disorder could wear, similar to glucose monitors for diabetes, warning of impending episodes.

As Hidalgo-Mazzei emphasizes, technology will not replace the therapeutic relationship, but it can complement it with accurate data, helping millions of people around the planet.

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