Bipolar 1 disorder (BD) is a common, severe, complex psychiatric illness characterised by extremes of mood and disordered thinking interspersed with periods of relative stability termed euthymia. A diverse range of neuroanatomical abnormalities have been found by Magnetic Resonance Imaging (MRI), most consistently, larger lateral ventricles in BD subjects when compared with controls[1]. In this study, the aim was to investigate the difference in volume and shape of lateral ventricles between euthymic BD 1 patient and healthy controls.

T1 weighted MR images for controls (n=60) and BD1 (n=60) patients, matched for age and gender, were segmented using ITKSNAP (inter-rater reliability, ICC=99.3; intra-rater, ICC= 99.5). The segmented shapes were modelled using SPHARM[2].This produced normalised and non-normalised images per subject, which analyse ventricle shape and regional volume change respectively. The images were statistically examined at every vertex across the surface for differences between patients and controls using MATLAB. A general linear model was used to test for any significant volume difference between the lateral ventricles...

Euthymic BD was associated with a significant increase in left lateral ventricle volume(F=4.11;p=0.045). There was an increase in the right lateral ventricular volume, however this did not reach significance (F=2.04;p=0.16).There was no distinction between patients and controls in the asymmetry between left and right ventricles (F=1.63;p=0.20).There were no significant changes in lateral ventricle shape between patients and controls. There was no relationship identified between ventricular volume and illness duration or lithium use.

BD patients were found to have larger lateral ventricles compared to controls, independent of illness duration, lithium use and duration of lithium use. Previous literature however has suggested a predominance of right ventricle volume increase in BD and left in schizophrenia[3].However, these previous studies focused on all BD as a whole (type I and II) while the patients in the current study are a more homogenous sub-group specifically of euthymic BD type I.Given the addition of psychosis to BD1 diagnosis, left ventricle enlargement may indeed...

Contact Details: Dr. Conor Waters. Senior House Officer, Galway University Hospital, Galway, Ireland. Departement of Psychiatry, Galway University Hospital, Galway Ireland: Professor C. McDolnald. Department of Radiology, Galway University Hospital, Galway, Ireland: Professor P. McCarthy.

1. Emsell L, McDonald C. The structural neuroimaging of bipolar disorder. International Review of Psychiatry. 2009;21(4):297-313. 2. Shen L, Farid H, McPeek MA. Modeling three-dimensional morphological structures using spherical harmonics. Evolution. 2009;63(4):1003-16. 3. McDonald C, Zanelli J, Rabe-Hesketh S, Ellison-Wright I, Sham P, Kalidindi S, et al. Meta-analysis of magnetic resonance imaging brain morphometry studies in bipolar disorder. Biological Psychiatry. 2004;56(6):411-7.