This chapter reviews the brain magnetic resonance imaging studies and discusses the types of basal ganglia structural changes that have been observed in patients with depression. Using a standardized rating scale, the researchers found a significantly increased incidence of moderately severe white matter and caudate hyperintensities. The occurrence of the hyperintensities was associated with atherosclerotic risk factors. They concluded that subcortical hyperintensities may play a role in rendering some individuals vulnerable to developing depression. Caudate hyperintensities were observed in 2 of 20 control subjects and in 7 of 19 elderly depressed patients. It is possible that there is a hereditary basis for smaller basal ganglia in depressed patients. In the elderly, subcortical hyperintensities are age-dependent, associated with atherosclerotic risk factors and are felt to reflect several pathologic changes. It is also possible that the smaller basal ganglia structures may occur secondary to the depressive illness.