In the United States, the word depression refers to everything from a transient mood state (feeling down) to a clinical disorder, Major Depressive Disorder (MDD). In order to receive a diagnosis of MDD, a person must experience marked distress and a decrease in level of functioning. In addition, the 2 weeks preceding the examination must be characterized by the almost daily occurrence of a dysphoric mood (e.g., sadness) or a loss of interest or pleasure (anhedonia) in almost all activities. The individual must also experience at least four (only three if both dysphoric mood and anhedonia are both present) of the following seven symptoms nearly every day for the 2-week period: significant weight change or change in appetite; Insomnia or Hypersomnia; psychomotor agitation or retardation; fatigue or loss of energy; feelings of worthlessness or excessive or inappropriate guilt; decreased concentration or indecisiveness; and suicidal ideation, plan, or attempt (Diagnostic and Statistical Manual of the American Psychiatric Association). Related disorders (i.e., other Mood Disorders) include Bipolar I and II Disorder (manic-depressive disorder), dysthymia, and cyclothymia.
Prevalence and Costs of Depression
MDD is the most commonly diagnosed psychiatric disorder among adults, with lifetime prevalence rates of 20–25% for women and 9–12% for men. At any given point in time, the prevalence rates are about 6% for women and 3% for men. MDD is fairly rare among children, but it begins to manifest itself at puberty. Depression has been diagnosed with increased frequency among young people, so that in the current 16-to-25 age group, about 20% have already suffered from a MDD. After late adolescence, the prevalence rates and gender differences are fairly constant over the human life span.
Depression tends to be a cyclical disorder. Among those who have one episode, the probability of a second episode is 50%, and among those with two episodes, the probability of a third episode is 75–80%. After the third episode, the disorder is likely to plague the person on a chronic basis, although episodes of the disorder may come and go even without treatment. The episodes are painful for the individuals with the disorder and those around them. As noted, the disorder interferes with functioning in both social situations and jobs. The costs are enormous to both the individual and society; for example, MDD is regularly rated among the top five most expensive health problems.
There are two major approaches to treatment of MDD— biological interventions and psychotherapies. The major biological intervention is antidepressant medications. The first major classification of antidepressants was called tricyclics because of the chemical structure of the medicines. Included in this group were such familiar medicines as amitriptyline (Elavil), imipramine (Tofranil), desipramine (Norpramin), and nortriptyline (Pamelor). These medications worked with about 55–65% of patients with MDD, but they have fairly severe side effects, including blurred vision, constipation, and orthostatic hypotension; furthermore, an overdose of these medications is likely to be lethal. Thus, they are currently used less frequently as a first line of treatment. Another class of antidepressant medications is the monoamine oxidase inhibitors (MAO inhibitors); examples include phenelzine (Nardil) and tranylcypromine (Parnate). These medications are as effective as the tricyclics for MDD and probably slightly more effective for a form of the disorder called atypical depression (e.g., symptoms of mood reactivity, extreme sensitivity to rejection, extreme fatigue, increased sleep, and weight gain or appetite increase). However, MAO inhibitors necessitate abstinence from several popular foods, so they are not very well tolerated. By far the most popular class of antidepressant medications currently is the selective serotonin reuptake inhibitors (SSRIs), which includes fluoxetine (Prozac), paroxetine (Paxil), sertraline (Zoloft), and citalopram (Celexa). These medications work with 60–70% of individuals with the disorder, and the side effects are relatively minor. However, one major drawback to the SSRIs is their fairly frequent side effect of inhibiting orgasm. There are several other less frequently utilized antidepressants, which do not fall into one of the preceding classes. One of those is buproprion (Wellbutrin), which may not be quite as effective as some of the other antidepressants, but it does have the advantage of facilitating sexual performance in some patients. For extremely difficult to treat depressions, electric convulsant therapy (ECT) and transcranial magnetic stimulation (TMS) may be employed. The latter therapies work very well, but there are fairly severe side effects, and the rates of relapse following the treatments are fairly high.
There are innumerable psychotherapies, but there are two that have been fairly extensively evaluated as treatments for MDD. Both of these therapies are short-term (16– 20 sessions), conducted over a period of 12–16 weeks. Both therapies focus on current life problems and are fairly directive (i.e., the therapist takes an active role in identifying and suggesting possible solutions to problems). The first of these is interpersonal psychotherapy (IPT). This therapy was designed to address interpersonal difficulties associated with MDD and focuses on one or more interpersonal problems. The topics of therapy include life transitions, losses, lack of social skills, and role conflicts.
The second effective psychotherapy for MDD is cognitive-behavioral therapy (CBT). This therapy focuses on the behavioral deficiencies (e.g., a lack of social skills) and cognitive styles (e.g., the belief that the depressed person causes bad things to happen, has always caused bad things to happen, and causes bad things to happen in many areas of his or her life) associated with MDD. With outpatients suffering from MDD, IPT and CBT are about equally effective.
Each is about as effective as antidepressant medications for mild to moderate depressions. Current studies are under way to determine if these psychotherapies are as effective as the antidepressant medications for more severe depressions. The limited available data suggest that a combination of antidepressant medications and one of these psychotherapies is both the most effective and the most enduring treatment for MDD.
Pharmacological interventions with children with MDD have been very disappointing; however, recent work has shown that fluoxetine (Prozac) is effective with adolescents who are age 15 or older. CBT has been used in small-sample studies with children, and it seems to be reasonably effective. CBT has been implemented in both the school and family settings.
At least two large research projects have suggested that behavioral marital therapy is an effective treatment for MDD when the depressed person is a partner in an unhappy marriage. It has been found that 50% of married depressed individuals are in unhappy marriages and that 50% of individuals in unhappy marriages are depressed. Thus, behavioral marital therapy may be useful to many married patients suffering from MDD.
One of the problems that has plagued the treatment of MDD is that a fairly large percentage of successfully treated individuals suffer from a relapse or recurrence of the disorder. Because the relapse rate is so great when antidepressants are taken for a fairly brief period of time (e.g., 3 months), it is strongly recommended that once an antidepressant medication is taken, it should be continued for at least 9–12 months. Combining antidepressant medication and psychotherapy (IPT or CBT) appears to decrease the relapse rate following treatment. It does appear that the most effective treatment for recurrent (three or more episodes) MDD is likely to be continued antidepressant medications.
Because of the increasing rates of MDD among young people, it is becoming increasingly important to prevent first episodes and recurrences of the disorder. Prevention programs, focused on individuals with some but not all the symptoms of MDD and individuals with pessimistic cognitive styles, have shown some promise. Small studies also suggest that combined CBT and IPT for individuals who have had an episode of MDD but are not currently depressed may decrease the recurrence rates of MDD.