There are some differences between younger and older people regarding the symptomatology of depressive disorders. Elderly people report less depressed mood. There is a high rate of anxiety in elderly patients with major depressive disorders compared with younger depressive patients. The high coexistence of anxiety and depression in the elderly suggests that depression is part of a depression-anxiety syndrome. Depression in elderly people is often hidden behind somatic symptoms, either because of somatization of the disorder or because of accentuation of symptoms of concomitant illness. Cognitive impairment caused by depression is usually referred to as pseudo-dementia or depression with dementia, and it is important to differentiate this condition from predementia. These types of symptoms are more common in elderly than in younger patients. Psychotic symptoms are also seen to a greater extent in the elderly. Some of the differences seen between younger and older people regarding the symptomatology of depressive disorders may be due to pathoplastic effects of aging and to differences between birth cohorts. Moreover, the aetiology of depression is more heterogeneous in elderly people than in younger. Inheritance has a lower impact in elderly people. However, biochemical changes in the aging brain and changes in neurodegenerative disorders are of importance. In these disorders, disturbances of the monoamines are recorded which evidently reduce the threshold for depression in the elderly; Depression is seen concomitantly with some somatic disorders. In several of these disorders, the illness presents initially with depression. Psychosociogenic factors also have importance for depression in late life. Married adults are at lower risk for depression than unmarried ones, and 30% of spouses of demented patients develop depressive disorders.