Depression and behavioural and psychological symptoms of dementia (BPSD) have a significant impact on the worsening of dementia because they increase the cognitive and functional decline and they have a significant impact on the vital prognosis. Physicians should be particularly careful in the use of antidepressants in the elderly, particularly in the frail elderly. Indeed, most studies have included patients aged at least 65 years without frailty criteria, but rarely those aged over 75 years and/or frail. As they are used in clinical practice, selective serotonin reuptake inhibitors, which initially appeared to have low risks, have been associated with many and dangerous adverse effects, particularly in elderly subjects. At present, there is a lack of data to assess the benefit-risk ratio of antidepressants in the treatment of depression and BPSD in patients with Alzheimer's disease or other dementias. Among the drugs frequently used in studies in order to evaluate these indications, citalopram and moclobemide are those associated with a low risk of adverse events and a significant effectiveness on depression signs and behavioural and BPSD. It is necessary to assess the effectiveness and adverse effects of antidepressants in demented elderly subjects through several studies.