Does Blood Flow Change according to Mood? Blood Rheology in Bipolar Disorder.

Objective: Bipolar disorder (BD) is associated with increased rates of cardiovascular diseases. There is growing evidence that blood viscosity may have a common role, correlated with well-known major risk factors that promote cardiovascular disease. In this study we aimed to investigate the whole blood viscosity (WBV) in different stages of BD. Methods: A total of 121 bipolar patients and 41 age-gender matched healthy controls were included. Forty-four of bipolar patients were in manic, 35 were depressed and 42 were in euthymic state. WBV was calculated from hematocrit and total plasma protein according to Simone's formula at low and high shear rates (LSR and HSR). Results: WBV at HSR of manic group was 16.91 +/- 1.01, depressive group was 17.23 +/- 0.80, euthymic group was 17.63 +/- 0.95, and control group was 17.52 +/- 0.71 (p=0.001). WBV at LSR of manic depressive, euthymic and control group were 53.10 +/- 20.58, 60.30 +/- 17.02, 68.91 +/- 20.33, and 62.01 +/- 19.28, respectively (p=0.001). Both WBV at HSR and LSR of manic group was significantly lower than that of the euthymic and control groups (p=0.001 and 0.010 respectively for HSR, p=0.001 and 0.011 respectively for LSR). WBV was significantly positively correlated with lipid profile except high density lipoprotein (HDL). Conclusion: Our results demonstrate a decrement in blood viscosity in manic episode compared with euthymics and controls. Positive correlation of blood viscosity with lipid parameters (except HDL), and negative correlation with number of previous manic episodes suggest that manic episode has favorable effect on cardiovascular risk regarding to blood viscosity.