Depression is quite different from having the blues. Whereas feeling sad or down on occasion is perfectly normal, depression, also called depressive disorder, is a serious illness that interferes with daily life, functioning, and relationships.

Causes of Depression

Causes of depression may be genetic, biochemical, environmental, or psychological, but there is no single known cause.

Research suggests that depression is a disorder of the brain, involving abnormal functioning of the areas that regulate mood, thinking, sleep, appetite, and behavior. In fact, MRI (magnetic resonance imaging) brain scans of people with depression appear different from those of people without depression. These findings, however, still don’t explain what causes depression.

There may be a genetic cause of depression, as it tends to run in families. But because people with no family history of the disorder also experience depression, there must be causes in addition to heredity. It’s likely a combination of genetic, environmental, and other factors.

Depression is sometimes preceded by a traumatic event—a particularly stressful and difficult situation that may be personal or job-related.

Depression and Other Illnesses

Sometimes a person with depression is also facing another significant illness. It may be not clear whether this is the result of the other illness or if depression has contributed to the development of another condition. In either case, effective treatment involves addressing both illnesses.

Several conditions that may increase a person’s risk for depression include post-traumatic stress disorder (PTSD), obsessive-compulsive disorder, panic disorder, social phobia, and generalized anxiety. These are all considered anxiety disorders. Eating disorders, such as anorexia nervosa or bulimia nervosa, may also coexist with depression, particularly in women.

Depression can occur along with alcohol and substance abuse or dependence. Research indicates that there is a high rate of coexistence of depression and substance abuse in the United States.

Sometimes people facing serious medical illnesses will also experience depression. Heart disease, stroke, cancer, HIV/AIDS, diabetes, and Parkinson’s disease have all been known to coexist with depression. In such cases, treatment of depression along with the other condition is extremely important, as studies have shown that people with depression and a major medical illness tend to have more-severe symptoms of each.

Depression in Women

Women tend to experience depression more commonly than men. In addition to postpartum depression (depression among new mothers), women may also be vulnerable to depression as a result of hormonal, biological, lifecycle, and psychological factors that differ from those of men. As well, some women experience depression as part of premenstrual syndrome (PMS), when hormonal changes occur around ovulation and before menstruation. Women may also become susceptible to depression around the time of menopause, when menstruation and the monthly menstrual cycle end, and in response to stresses associated with family, work, abuse, or hardship.


Symptoms of depression vary from person to person and by form of depression. Signs of depression include:

  • Persistent sad, anxious, or “empty” feelings
  • Feelings of hopelessness and/or pessimism
  • Feelings of guilt, worthlessness, and/or helplessness
  • Irritability, restlessness
  • Loss of interest in activities or hobbies once pleasurable, including sex
  • Fatigue and decreased energy
  • Difficulty concentrating, remembering details, and making decisions
  • Insomnia, early-morning wakefulness, or excessive sleeping
  • Overeating or appetite loss
  • Thoughts of suicide, suicide attempts
  • Persistent aches or pains, headaches, cramps, or digestive problems that do not ease with treatment

Diagnosing Depression

Diagnosis of depression is important because it is highly treatable. An early diagnosis increases the likelihood of effective treatment and reduces the likelihood of a recurrence.

How is depression diagnosed?
A visit to a primary care doctor can begin the process of diagnosing depression. The process involves a medical evaluation to rule out a medical cause of depression, such as medications, viruses, or a thyroid disorder.

If other health factors are ruled out, the doctor will conduct a psychological evaluation or refer the patient to a mental health professional, who will complete the diagnosis process. Factors including family history of depression, history of symptoms, alcohol and drug use, and thoughts of suicide will be part of the complete evaluation.

Treating Depression

Depression is treated with psychotherapy, also called talk therapy, and with medication. Depending on the individual and the form and severity of depression, these methods may be used alone or in combination.

Therapy for Depression:

Psychotherapy, or talk therapy, for depression may be short- or long-term, depending on the individual and the nature of the disorder. As well, individual considerations will help determine whether a person can be treated with psychotherapy alone or also requires medication.

The two main types of psychotherapy are cognitive-behavioral therapy (CBT) and interpersonal therapy (IPT). The goal of CBT is to teach new ways of thinking and behaving, which are intended to change negative thoughts and behaviors that may contribute to depression. IPT aims to address issues concerning troubled relationships that may contribute to depression.

Electroconvulsive Therapy
Electroconvulsive Therapy (ECT) may be used in patients whose depression does not improve with antidepressants and psychotherapy. Today’s ECT is greatly improved over earlier forms of “shock therapy” and can provide relief in severe cases. Side effects are generally short-term; they include confusion, disorientation, and memory loss.

Patients receiving ECT are given a muscle relaxant and then put under brief anesthesia so that they don’t feel the procedure. ECT is given only a few times or as maintenance over a longer period, depending on the individual case. Patients often also take antidepressants while undergoing ECT.