Prolidase levels increased in bipolar disorder
MedWire News: Prolidase levels are higher in patients with bipolar disorder than in those without the condition, and could serve as a trait marker in bipolar disorder diagnosis, say Turkish researchers.
Prolidase - a proline splitting enzyme - is thought to play a role in oxidative metabolism, which has been found to be impaired in patients with bipolar disorder, explain Salih Selek (Harran University, Sanliurfa) and colleagues.
This, say the researchers, "lends support to the hypothesis that oxidative stress may contribute to the pathophysiology of bipolar disorder."
To investigate prolidase activity in patients with bipolar disorder, and assess its effectiveness as a diagnostic marker, the team studied 66 patients with bipolar I disorder (31 women) and 66 mentally healthy controls (31 women) who were aged a mean of 32 and 30 years, respectively.
Of the patients with bipolar disorder, 22 were manic, 20 were depressive, and 24 were euthymic.
Blood samples were collected from all of the participants and tested for prolidase activity using a specific assay.
The researchers found that prolidase levels were significantly higher in bipolar disorder patients than controls, at 534.58 versus 415.61 U/l, respectively.
However, there were no significant differences in prolidase levels among manic, depressive, and euthymic bipolar disorder patients, at 532.05, 538.96, and 532.66 U/l, respectively.
Receiver-operating characteristic curve analysis revealed that a prolidase level cutoff point of 502.94 U/l had a positive and negative predictive value for bipolar disorder of 98.5% and 92.4%, respectively.
Selek and team conclude in the Journal of Affective Disorders: "Prolidase activity is impaired in bipolar disorder, which may be associated with oxidative stress."
They add: "Prolidase activity may be a trait marker for diagnosing bipolar disorder."
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By Mark Cowen