Depression in the elderly is difficult to treat because compared to younger patients, depression in the elderly tends to last longer with an average duration often exceeding one year, and episodes occur more frequently, often becoming chronic. Additionally, the prognosis for elderly depression is worse compared to other age groups, primarily due to the coexistence of cerebrovascular diseases and other physical comorbidities, recent acute illnesses, long-term ongoing diseases, as well as the presence of delusions and a lack of social support systems. Thus, depression in the elderly is quite challenging to treat.