One way to avoid depression is to be aware of various risk factors that predispose a person to the condition.

Although you can’t alter your genetic predisposition, understanding genetic risk can often motivate people to address their nongenetic risks, which they can control.

Someone with a close family member who suffers from depression is more likely to experience it as well.

And in rare families, there are very high genetic risks for a certain form of depression known as manic depressive disorder — a condition characterized by intermittent bouts of emotional highs known as mania (which include euphoria, impulsivity, irritability, psychosis) and low depressive moods.

Another risk factor is a death or personal loss. The sadness and grief that people experience following the death of a loved one can sometimes bring on a full-blown depressive episode.

Other major life events — such as loss of employment, decreased income, separation, or divorce — can bring on depression.

And surprisingly, even positive events including a new job, getting married, a promotion, having a baby, or graduating from college have been known to trigger depression in some people.

People with conflicted relationships are more likely to get depressed than those in healthy relationships. Social isolation can also increase a person’s risk for low moods and depressive episodes.

Not surprisingly, people who abuse drugs and other substances are at a higher risk for depression; approximately 30 percent of them develop the condition.

Of course, people who are feeling depressed sometimes abuse substances to try to deal with their emotional discomfort.

In addition, many physical illnesses increase the risk for depression. People suffering from chronic pain or sleep difficulties have higher rates of depression than those without such problems.

Some medicines used to treat illness also can affect a person’s mood, and actually turn out to be the underlying cause of a depressive episode.

Women face a greater risk for depression than men, but the reason for this discrepancy is not entirely clear. A recent study published in the journal Brain, Behavior, and Immunity suggests that immune function changes, as well as increased inflammation could play a role.

Earlier studies suggested that changes in the immune system could contribute to mood changes. This led researchers at the Medical College of Wisconsin to assess immune function and regulation by measuring C-reactive protein (CRP) levels and other biomarkers in both men and women who were suffering from depression.

The scientists suspected that women would have higher levels of inflammation, as measured by these biomarkers. (Other research has shown that women who use oral contraception experience increased levels of CRP.)

As predicted, measures of inflammation were higher in depressed women than in men suffering from depression.

The biological mechanisms underlying these interactions are not completely distinct, but it’s possible that the association could be linked to interactions between sex hormones and the immune system.