By Elaine Cassel
Depressive disorders, including major depressive disorder
and dysthymic disorder
, are serious, disabling illnesses. It is estimated that one in five individuals is affected by a mood disorder
in his or her lifetime. The economic costs to society and the personal costs to individuals and families are enormous. In the U.S. alone, the estimated monetary costs for depression exceeded $44 billion in 1990. The personal costs are reflected by higher mortality and impairment in multiple areas of functioning. The World Health Organization estimates that major depression is the fourth most important cause worldwide of loss in disability-adjusted life years, and will be the second most important cause by 2020. A widely publicized emphasis on recognizing and treating depression as well as the development of many new antidepressants
have contributed to explosive growth in antidepressant prescribing and increasing pharmacy costs for health plans. Newer antidepressants have led to wider but sometimes confusing choices for clinicians.
A report released March, 18, 1999 and sponsored by the U.S. Department of Health and Human Services, Agency for Health Care Policy and Research tells us what we know and, more importantly, what we don't know about the effectiveness of therapeutic treatment interventions for depression.
The report is the result of a meta-analysis of more than 300 clinical trials of depression therapies from 1980 to 1998. More than 300 randomized trials evaluated newer pharmacotherapies for depression. The largest number of comparisons (n=206) were between newer antidepressants (selective serotonin reuptake inhibitors, also known as SSRIs) and older antidepressants (known as trycyclic antidepressants, or TCAs). Over 100 studies compared the efficacy of newer antidepressants to placebo
. The report identified several methodological flaws in the trials examined. While more than 90 percent of the included trials used double-blind design
, (gl) 90 percent of the trials were short duration (6-8 weeks). Trial reporting was often incomplete. Less than one-third of studies described study settings, few studies described the nature and content of clinical interactions between providers and patients, and fewer than 10 percent described ethnic background or socioeconomic status of the participants. Secondary outcomes (health-related quality of life, level of functioning, suicides) were reported too infrequently for analysis.
The report concludes that more than 80 studies prove that the newer SSRIs (such as Prozac) are more efficacious than placebo for treating adults with major depression. Response rates were 50 percent for active treatment compared to 32 percent for placebo. However, the SSRIs are no more effective than the older TCAs. In addition, both types of medications have side effects. For people taking SSRIs these include diarrhea, nausea, insomnia, and headache, for trycyclics dry mouth, constipation, dizziness, blurred vision, and tremors. No studies examined compared psychotherapy
with psychopharmacologic interventions nor compared medication alone to a combination of psychotherapy and medication. None examined the long-term efficacy of antidepressants of either nature, nor the effectiveness of antidepressants for children and adolescents.
Furthermore, although the comparison of treatment versus placebo conditions seems convincing (50 percent versus 32 percent improvement, respectively) the fact that the medications all have side effects calls into question whether the double-blind design
protects the research results from bias. For those patients in the treatment group who experience side effects, the double-blind "cover" is blown if they put two and two together. What effect does their knowing (or at least having a clue or a hunch) that they are receiving the treatment have on their symptoms? How can the researchers not be biased in their observations of the subjects who experience side effects (since they also are supposed to be clueless about who is receiving the treatment)? Roger Greenberg, psychologist at State University of New York Health Science Center at Syracuse suggests that given these possibilities, the conclusions of treatment efficacy might be illusory.
If the placebo effect crosses over into the treatment group, the power of the mind to "cure" itself may be greater than the research conclusions indicate--a possibility that researchers need to address. Until then, consumers of antidepressants should employ critical thinking
when reading research reports and drug inserts--and not be "blinded" by claims of the double-blind design. It may have some "blind" spots of its own.
To learn more about depression visit this Netlab:
"Depression: The Common Cold of Mental Disorders"