An Examination of the Relationship Between Grey Matter and Depression and Anxiety Scores

In 2010 7.4% of disability-adjusted life-years (DALYs) were attributed to mental and substance abuse disorders. Of that, approximately 40.5% could be attributed to depressive disorders.  The urgency to better understand these disorders increases as the number of individuals afflicted with depressive disorders rises (Whiteford et, al, 2013).  The advent of neuroimaging technology has allowed the study of mood disorders to advance rapidly in humans. In the brains of patients with Major Depressive Disorder (MDD), the grey matter (GM) in areas such as the prefrontal cortex and the temporal lobe have been found to be reduced when compared to healthy controls. The amygdala and hippocampus in particular have been consistently shown to have a decreased volume in MDD patients (Hamilton et. al, 2008; Tae et. al, 2008), however, this is not the case if the patients are being medicated for their disorder (Hamilton et. al, 2008; Downar et. al, 2014). The present study sought to identify a correlation between the volume of a priori selected areas (i.e. hippocampus, amygdala, and prefrontal cortex), and depressive symptoms reported by the individual at the time of the study. Most patients with MDD in the present study were medicated and thus would not have as significant a volume decrease as their unmedicated counterparts, however, a negative correlation between depressive symptoms and GM was still expected across all  participants.  Preliminary results have identified no apparent relationship between GM in each region and MDD, as scored using the Beck Depression Inventory.  The next stage of this ongoing analysis is aimed at determining whether grouping the a priori regions provides a more accurate relationship to both depression and anxiety scores (with the latter determined using the Beck Anxiety Inventory).