Subclinical depression, which is also referred to as subthreshold depression, is defined as the presence of depressive symptoms that are not yet severe or persistent enough to warrant a diagnosis of major depressive disorder (MDD).
If such symptoms are present almost every day for a minimum of 2 weeks, then this would usually warrant a diagnosis of MDD, or major depression.
Study co-author Dr. Samuel Y.S. Wong — of the Jockey Club School of Public Health and Primary Care at the Chinese University of Hong Kong — and colleagues note that around 10–24 percent of people are estimated to be affected by subclinical depression in their lifetime, and the condition is a key risk factor for MDD.
Previous research suggests that psychotherapy may be a beneficial treatment strategy for subclinical depression, and that it could limit the progression to MDD.
For the new study, recently published in the Annals of Family Medicine, Dr. Wong and colleagues investigated whether mindfulness meditation might benefit people with subclinical depression.
Mindfulness meditation is a psychological practice that focuses on being fully aware of experiences in the present moment, rather than being distracted by what is happening around us.
"[...] although the developers of behavioral activation have suggested and encouraged therapist use of mindfulness as a therapeutic method to reduce rumination in depressed patients," write the authors, "no large study has explicitly combined behavioral activation techniques with mindfulness skills and evaluated their combined effectiveness in reducing depressive symptoms."
Major depression lower in meditation group
The researchers enrolled 231 adults, all of whom had subclinical depression, to their study. Subjects were recruited from 16 outpatient clinics in Hong Kong.
Subjects were randomized to one of two groups for a total of 8 weeks: 115 participants took part in a 2-hour session of mindfulness meditation each week, while the remaining 116 participants received usual care, with no psychological intervention.
The team used the Beck Depression Inventory-II scale to assess depressive symptoms among the subjects at study baseline and 8 weeks, 5 months, and 12 months later.
At 12 months, the researchers found that the subjects in the mindfulness meditation group were less likely to have developed MDD than those who received usual care; MDD was identified in 10.8 percent of participants in the mindfulness meditation group, compared with 26.8 percent in the usual care group.
What is more, the study revealed that mindfulness meditation was associated with a small reduction in depressive symptoms at 12 months, compared with usual care.
According to the National Institute of Mental Health, around 16.2 million adults in the United States had at least one episode of major depression in 2016.
Based on these study results, Dr. Wong and colleagues suggest that mindfulness meditation could be one strategy to help prevent MDD.
The researchers conclude:
"[...] we have shown that BAM [behavioral activation with mindfulness] is a potentially feasible and efficacious intervention for reducing depressive symptoms and preventing major depression among people with subthreshold depression in primary care."
The team plans to conduct further studies that will look at how mindfulness meditation could be integrated into primary care settings as a way of reducing MDD.