Ofer Pasternak1, Carl-Fredrik Westin1, Sylvain Bouix1, Martha E. Shenton1,2, Marek Kubicki1,2
1Brigham & Women's Hospital, Harvard Medical School, Boston, MA, United States; 2VA Boston Healthcare System, Harvard Medical School, Brockton, MA, United States
We use the Free water analysis method to test the biophysical underpinnings of FA decreases in first episode Schizophrenia patients compared with matched controls. We find that an increase in the free water volume accounts for most group differences, otherwise explained with FA decrease and MD increase. Therefore it is unlikely that the FA reductions are caused by myelin (shape) changes, but rather by extra-cellular (volume) changes. Our findings lead us to speculate a new etiology for the early stages of Schizophrenia: a whole brain process affects the extra-cellular space, causing localized myelin deficiencies.