Depression is typically caused by a combination of biological, genetic, and psychological factors.  Some types of depression run in families, indicating that a biological vulnerability can be inherited.  This seems especially to be the case with bipolar disorders.  Studies of families in which members of each generation develop bipolar disorder found that those with the illness have a somewhat different genetic makeup than those who do not get ill.  However, the reverse in not true:  Not everybody with the genetic makeup that causes vulnerability to bipolar disorder has the illness.  Apparently, additional factors such as a stressful environment, may be involved in its onset.  Major depression also seems to have a generational context in some families.  However, it can also occur in people who have no family history of depression.  Whether inherited or not, major depressive disorder is often associated with having too little or too much of certain brain neurochemicals.

General risk factors include:

• Women are twice as likely to experience depression; This holds true across cultures
• Being between the ages of 20-40
• Chronic anxiety/stress can lead to depression; Excessive levels of fight or flight hormones like cortisol and norepinephrine can lead the body into a depressive state

General psychological health also plays a role in vulnerability to depression.  People who have low self-esteem, who consistently view themselves and the world with pessimism or who are easily overwhelmed by stress are prone to depression.  A serious loss, chronic illness, difficult relationship, financial problem, or any unwelcome change in life patterns (divorce, loss of control over one’s environment) can also trigger a depressive episode.

For college students, important stress-producing situations which can trigger depression are:

• Separation from family (chances to gain independence vs. distance from positive support provided by family)
• Freedom (few rules, but must make many decisions on own)
• Competition (for grades, graduate school, jobs, dating, etc.)
• Peer Pressure (values conflicts, alcohol, drugs, sex, partying v. studying)
• Career Choice(s)
• Relationships
• Financial problems 

Among the most common reasons why college students become depressed are:

• Unexpected and problematic adjustments to college life
• Difficulties in establishing new relationships, especially with roommates and with others students in residence
• Loss of a significant relationship
• Conflicts with parents/family; Clash of values, behaviors, and expectations