According to a recent study, although treating major depressive disorder has benefits in the short-term, over a longer period of time, it may make the condition worse.

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New research asks how effective the treatment of depression is over long periods of time.

Major depressive disorder is a serious, debilitating mental illness. In the United States, it affects more than 16.1 million people over the age of 18. Although its prevalence is high, it is still a difficult condition to treat.

Treatments include medications such as selective serotonin reuptake inhibitors and talking therapies, such as cognitive therapy. No case of depression is the same, and often, individuals receive a range of treatments across their lifetime.

How well the treatment of depression works has come under scrutiny over recent years, and the debate is by no means over. The latest study, published in the journal Psychotherapy and Psychosomatics, adds another dimension to this ongoing conversation.

Clinical treatment compared with community

Individuals with major depressive disorder who receive medication or cognitive therapy often see a reduction in their depressive symptoms and experience significantly longer times before relapse.

But over the longer-term, the picture is less clear. This is primarily because studies generally only run for 1–2 years. This gap in our knowledge could be important.

Around 85 percent of patients within specialized mental healthcare settings experience another major depressive episode within 15 years, but only 35 percent of people with major depressive disorder in the community have a relapse in the same time frame.

These figures come from a 2010 study that looked at predictors of depressive episodes. They concluded that "[c]linical factors seem the most important predictors of recurrence."

Why might there be such a difference in relapse risk? The new study set out to investigate whether or not this disparity might be due to the treatments they received.

The research was conducted by Jeffrey R. Vittengl, from the Department of Psychology at Truman State University in Kirksville, MO.

There are a number of potential reasons why this difference in relapse rates has been measured. For instance, perhaps those in a clinical setting receive more rigorous screening and therefore relapses are picked up and reported more faithfully.

Or, maybe individuals who are in an institution are there because they have more severe major depressive disorder or other conditions that impact their mental health. Or perhaps some treatments do harm over the longer-term.

Delving into survey data

To answer these questions, researchers took data from The Midlife Development in the United States Survey, which was initially set up to "investigate the role of behavioral, psychological, and social factors in accounting for age-related variations in health and well-being in a national sample of Americans."

This survey was conducted in three waves: 1995–1996, 2004–2006, and 2013–2014. In each wave, the questions were answered by the same nationally representative sample of non-institutionalized adults. By the end of the study, there were 3,294 participants. At study baseline, they were all aged 25–74.

Among other conditions, the interview assessed for major depressive disorder. The questionnaires asked about treatments and whether or not there had been a relapse in the preceding 12 months. The 12-month prevalence across the three periods of time were 13.3, 10.5, and 9.9 percent, respectively.

Of the individuals with major depressive disorder during the previous year:

  • 38.1 percent received no treatment
  • 25.2 percent received inadequate treatment (including medication)
  • 19.2 percent received inadequate treatment (without medication)
  • 13.5 percent received adequate treatment (including medication)
  • 4.1 percent received adequate treatment (without medication)

"Adequate" treatment was defined as eight or more visits to a psychiatrist, psychologist, counselor, or social worker if not taking medication, and four or more visits if medication was being taken. "Inadequate" was defined as fewer visits, and "no treatment" meant there had been no visits or medication.

The long-term effects of treatment

When the data were analyzed, the findings were surprising. The team found that, compared with the group who received no treatment, symptom intensity was significantly higher in those who received inadequate treatment, adequate treatment, and treatment with or without medication.

So, as far as symptom intensity was concerned, the no-treatment group fared best.

Also, symptoms were worse following treatment that included medication versus treatment without medication.

Because these data came from non-institutionalized adults all assessed using the same diagnostic guidelines from a fair cross-section of the population, the differences observed are more likely to be down to the treatment interventions.

However, more research will be needed to confirm these findings. If they are shown to be accurate, it raises a raft of serious concerns about the future treatment of depression.