Oh, snap - Early history of depression linked to Alzheimer’s later in life

“History of depression, and particularly an early onset, but not presence of depressive symptoms increased the risk for Alzheimer disease. This risk was not mediated by smaller hippocampal or amygdalar volumes.”: iTWire - Early history of depression linked to Alzheimer’s later in life

In other words, there's a correlation, but they don't know the cause yet.