Causes and Risk Factors

Several factors, or a combination of factors, may contribute to depression.

Genes — people with a family history of depression may be more likely to develop it than those whose families do not have the illness.

Personal History — Older adults who had depression when they were younger are more at risk for developing depression in late life than those who did not have the illness earlier in life.

Brain chemistry — people with depression may have different brain chemistry than those without the illness.

Stress — loss of a loved one, a difficult relationship, or any stressful situation may trigger depression.

Vascular Depression

For older adults who experience depression for the first time later in life, the depression may be related to changes that occur in the brain and body as a person ages. For example, older adults may suffer from restricted blood flow, a condition called ischemia. Over time, blood vessels may stiffen and prevent blood from flowing normally to the body’s organs, including the brain.

If this happens, an older adult with no family history of depression may develop what is sometimes called “vascular depression.” Those with vascular depression also may be at risk for heart disease, stroke, or other vascular illness.

Depression Can Co-occur With Other Illnesses

Depression, especially in midlife or older adults, can co-occur with other serious medical illnesses such as diabetes, cancer, heart disease, and Parkinson’s disease. Depression can make these conditions worse and vice versa. Sometimes medications taken for these physical illnesses may cause side effects that contribute to depression. A doctor experienced in treating these complicated illnesses can help work out the best treatment strategy.

Because many older adults face these illnesses along with various social and economic difficulties, some health care professionals may wrongly conclude that these problems are the cause of the depression -- an opinion often shared by patients themselves.

All these factors can cause depression to go undiagnosed or untreated in older people. Yet, treating the depression will help an older adult better manage other conditions he or she may have.

For a list of helpful resources, visit the National Institute of Mental Health (NIMH).