<qa>  What is the hallmark of depression in late life?The vast majority of patients with mood disorders are managed at ambulatory careprimary care settings around the country. Ambulatory care clinics have become defacto settings for the diagnosis and management of psychiatric problems, especially in the elderly. Depression, particularly in the elderly, is associated with several chronic medical illnesses including malignancies, chronic obstructive pulmonary disease, and gastrointestinal, vascular, autoimmune and demyelinating disorders. Acknowledging the overall robust association between medical illness and mood disorders, the NIH consensus statement on depression in the elderly states, The hallmark of depression in late-life is its association with medical comorbidity. While the precise mechanisms by which coexisting medical illnesses contribute to depression remain unclear, neuroanatomical, vascular, immunologic, psychosocial and or a combination of these mechanisms have been invoked as possible pathways by which medical disorders may lead to depression in the elderly. 