[Depression in old age, part 1 : Origin, clinical symptoms, diagnosis and interaction between depression and dementia].

Depression is one of the most frequent mental disorders in old age. A huge variety of very different causal factors can contribute to late life depression as a common final outcome. The pathogenic pathways of depression overlap with those of frequent somatic medical conditions, such as diabetes and ischemic heart disease. Age-specific modulations of symptom presentation are described in this article with special emphasis on subthreshold depression and the complex mutual relationship between depression and dementia is presented.