Telomere Length in Bipolar I Disorder and Its Relationship with Serum Cortisol Level

Telomere length (TL), a biological marker of cellular aging, has been linked to several psychiatric disorders. Telomere length has been found to be shorter in bipolar disorder; however, the potential role of stress-related biological factors, such as cortisol, has not been fully clarified. This study aimed to investigate TL in bipolar I disorder (BD-I) and its relationship with clinical characteristics and serum cortisol levels.

The study included 38 patients with BD-I and 32 age- and sex-matched controls. All patients were evaluated using the Hamilton Depression Rating Scale, Young Mania Rating Scale, and Clinical Global Impression. Telomere length and serum cortisol levels were measured from blood samples obtained from both groups.

A significant difference was observed in the TL between the patient and control groups (P < .01) as patients had shorter TL. Although cortisol levels were higher in patients, the difference was not statistically significant (P > .05). No relationship was found between cortisol level and TL. Telomere length was also not related to clinical variables such as the number of first episodes, presence of psychotic features, seasonal pattern, remission status, or history of hospitalization (P > .05).

Patients with BD-I demonstrated shorter TL than healthy controls. The lack of association between TL, clinical features, and cortisol suggests that shorter telomeres may be related to BD-I itself. This is to our knowledge, this is among the first studies to investigate the relationship between cortisol levels and TL in BD-I. Further research is needed to clarify underlying mechanisms and the role of biological aging in bipolar disorder.