Orbitofrontal microstructural characteristics in bipolar disorder type i patients and their siblings: a difusion tensor imaging study

  • MD Francisco Romo-Nava, Affective Disorders Clinic, Instituto Nacional de Psiquiatría "Dr. Ramón de la Fuente", Mexico
  • Ms in Sc Sarael Alcauter-Solórzano, Neuroimaging Department, Instituto Nacional de Psiquiatría "Dr. Ramón de la Fuente", Mexico
  • MD Doris Gutiérrez-Mora, Affective Disorders Clinic, Instituto Nacional de Psiquiatría "Dr. Ramón de la Fuente", Mexico
  • MD Jorge González- Olvera, Instituto Nacional de Psiquiatría "Dr. Ramón de la Fuente", Mexico
  • MD María de Lourdes Martínez-Gudiño, Instituto Nacional de Psiquiatría "Dr. Ramón de la Fuente", Mexico
  • MD Roger Carrillo- Meza, Neuroimaging Department, Instituto Nacional de Psiquiatría "Dr. Ramón de la Fuente", Mexico
  • MD Carlos Berlanga- Cisneros, Affective Disorders Clinic, Instituto Nacional de Psiquiatría "Dr. Ramón de la Fuente", Mexico
  • MD Claudia Becerra-Palars, Affective Disorders Clinic, Instituto Nacional de Psiquiatría "Dr. Ramón de la Fuente", Mexico

Introduction.
Bipolar disorder (BD) is a complex illness. Some neurobiological characteristics documented in BD are putatively shared among non- affected siblings (NAS). Neuroimaging techniques like MRI diffusion tensor (DT) are useful in evaluating white matter microstructural characteristics. We used DT to evaluate the orbitofrontal region (implicated in mood regulation) in BP type I patients and their NAS.
Objective: To compare orbitofrontal regions of interest (ROI) fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values between BDI, their NAS, and control subjects groups.
Methods: This study was performed in México at the National Institute of Psychiatry “Dr. Ramón de la Fuente”. Strict criteria were applied to recruit non- comorbid BDI patients (n=5), their NAS (n=4), and controls (n=5). DT scans were obtained using a 3.0 T Philips Scanner. A blind to diagnoses investigator (FR) manually traced the ROI in three orbitofrontal subregions on each hemisphere. FA and ADC values on each RI were obtained and compared between groups.
Results: A significant difference between the three groups was found in ADC on the right caudal medial orbital region (chi-square=7.491,df=2, p=0.024), being ADC values in BDI>Control>NAS, with a significant difference between BDI vs. control (p=.047), and BDI vs. NAS (p=.014). FA values on the left rostral medial orbital region were significantly different between BDI vs. control groups (p=.028), being FA values smaller for the BDI group.
Conclusions: We evaluated microstructural characteristics of orbitofrontal subregions in BPI and NAS. This preliminary findings show orbitofrontal subregional differences and similarities between BPI and their NAS.