Uric acid levels may be a biological marker for the differentiation of unipolar and bipolar disorder: The role of affective temperament

Background: The aim of this study was to investigate whether uric acid levels are different between patients with remission period of bipolar disorder type I (BD) and patients with remission period of major depressive disorder (MDD). Methods: For this aim 41 patients diagnosed with BD and 30 patients diagnosed with recurrent MDD according to DSM-IV who were in remission period for at least 8 weeks were evaluated consecutively. The median age and gender distribution of the two groups were similar. Subjects with comorbid psychiatric diagnosis and/or severe medical illnesses were excluded. Affective temperament was evaluated with TEMPS-A (Temperament Evaluation of Memphis, Pisa, Paris and San Diego Autoquestionnaire). Plasma uric acid levels were recorded in mg/dl. Results: The uric acid levels of BD patients were found higher than patients with MDD and healthy controls. Additionally uric acid levels of MDD patients were lower than patients with BD and healthy subjects (F=4.183, p=0.039). A moderate correlation between hyperthymic and irritable temperament scores and uric acid levels was detected in both patient groups and in healthy controls. A negative correlation was observed between depressive temperament and uric acid levels only in MDD group. Limitations: The measurements of temperament were estimated depending on the patient's statement. The medications that patients used were not controlled. Conclusion: There is a purinergic dysfunction not only in BD but also in MDD patients. High uric acid levels are associated with hyperthymic and irritable temperament scores whereas low uric acid levels are associated with depressive temperament scores. (C) 2014 Elsevier B.V. All rights reserved.