Structural Brain Changes in Mood Disorder: Clinical Correlates and Significance

Studies of brain structure in mood disorders have revealed a number of intriguing findings. These findings include brain volume loss, white matter abnormalities, decreased caudate volume, increased thalamic volume, and temporal lobe asymmetry. Especially interesting is the disparate nature of some findings across studies. Some results, such as an increased incidence of white matter signal hyperintensities appear to cross diagnostic lines, and may or may not have same significance for each diagnosis. This article explores possible explanations for the often confusing study outcomes. In particular, the effects of inherent biases, subject selection, and methods of image analysis are discussed. Finally, the contribution of co-morbid diagnoses and cigarette smoking to studies of brain structure are explored.