Major depression occurs in 1 to 4% of elderly people in the community. Older people are often affected by recent difficult experiences, such as the death of friends or family members, as well as thoughts about their own death. Similar to the younger population, women are twice as likely as men to be affected by depression. Between the ages of 70 and 85, both the incidence and the prevalence of major depression double. In addition to its effects on individual and family morale, depression in later life leads to an array of medical, psychosocial, and economic consequences, including increased mortality, morbidity and disability, decreased quality of life, as well as increased health care costs and use of health services.
Depression in old age is intertwined with medical and neurological illness. Many symptoms that are part of the depressive symptom cluster may occur in older people for reasons other than depression. The greater the medical burden, the higher the risk of depressive symptoms or syndromes. In medical settings, the prevalence of late-life depressive syndromes increases. In patients with a recent acute myocardial infarction, depression increases the risk for mortality by a factor of 4, not to mention the risk for other adverse cardiac outcomes. However, depression after coronary events remains under-diagnosed and under-treated. Similar reciprocal relationships exist between depression and dementia. The prevalence of depression (major or minor) in Alzheimer’s disease ranges between 30 and 50%, and it is likely that the more severely demented cluster around 50%. The development of provisional criteria for the diagnosis of depression in patients with Alzheimer’s disease may help clinicians reverse the current state of diagnosis and treatment.
Even with the knowledge of these effects, older people remain under-treated and are too often considered to be “naturally frail” due to their age. One reason for this designation may be due to a perception that the diagnosis and treatment of depression in older people presents a challenge.  However, when the diagnosis has been correctly made, and the treatment is carefully administered, antidepressants have comparable efficacy and safety to what is reported in younger adults. The real issue is the correct and appropriate choice of drug therapy, one that is symptom-specific and does not hinder treatment of frequent and common comorbidities.