Changes to the white matter in the brain are strongly associated with depression in older people but it is unclear whether changes to the brain cause depression, or depression causes changes to the brain or if a third, unknown, factor causes both the depression and the white matter changes. A pan-European study of 639 older adults gave them brain scans and tested them for cognitive function, quality of life, disability and depression. When the tests were repeated after a year severity of white matter changes was shown to 'independently and significantly' predict depressive symptoms.
Teodorczuk, A. ... [et al] - White matter changes and late-life depressive symptoms British Journal of Psychiatry 191: 212-217