Sub-regional volumes changes of the corpus callosum in the drug naive patients with late-onset depression.

Although sub-regional analysis methods of the corpus callosum (CC) have been developed, there has been no in vivo magnetic resonance imaging (MRI) study on a sub-regional volume analysis of the CC of late-onset depression (LOD). The aim of this study was to investigate the CC volume differences between LOD subjects and healthy elderly controls using a sub-regional analysis technique. Forty subjects with LOD and thirty nine group-matched healthy control subjects underwent 3T MRI scanning, and sub-regional volumes of the CC were measured and compared between the groups. The volumes of total (F=5.8, p=0.001), the anterior (F=5.2, p=0.001) and the posterior CC (F=5.1, p=0.001) were significantly reduced in the LOD group as compared to the control group. We measured cognitive functions in several different domains (language functions, verbal learning, visuospatial functions, delayed recall, memory consolidation, recognition memory, and executive functions) through the Korean version of the Consortium to Establish a Registry for Alzheimer's Disease. The anterior CC volume in the LOD group showed significant positive correlation with the Verbal Fluency scores. The posterior CC volume in the LOD group was positively correlated significantly with the Word List Memory, the Word List Recall and the Constructional Praxis scores. This study is the first to elaborate the sub-regional volume differences of the CC between controls and LOD patients. These structural changes in the CC might be at the core of the underlying neurobiological mechanisms in LOD.