Abstract: Increasing evidence shows that Alzheimer’s disease （AD） is closely associated with depression. Depression is an important risk factor of AD and depressive symptoms often occur among patients with AD. This review focused on the relationship of these two diseases and summarized the underlying pathological mechanisms， including vascular factor， β-amyloid protein， glucocorticoid steroids and hippocampal atrophy， nerve growth factors and excitatory amino acid， which may provide a new insight into developing novel treatment strategies for AD and depression.

Key words: Alzheimer&rsquo, s disease, depression, mechanism of comorbidity