Neuropsychology researchers at Chicago's Rush University Medical Center made their findings public Monday.
Scientists they found little change in depression symptoms in the six to seven years prior to patients being diagnosed with Alzheimer's and no change in symptoms for three years following diagnosis.
Previous studies found people who suffer from depression are twice as likely to develop dementia later in life.
Authors of the Rush study say their findings show that if an Alzheimer's patient has depression, the depression should be treated.
