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A fishy depression treatment

With many trials already conducted on the topic of fish oil and depression, the question of overall impact still remained. This is the latest update to the Cochrane systematic review on the topic.

Study under review: Omega-3 fatty acids for depression in adults


Depression is the leading cause of disability worldwide, with an estimated 350 million people suffering from this mood disorder. Major depressive disorder (MDD) is a type of depression defined as a state of extreme unhappiness and inability to feel pleasure lasting at least two weeks. Figure 1 shows a breakdown of major depression in the US.

Figure 1: Prevalence of major depressive episodes in the US in 2013


MDD can be very debilitating, has a high rate of recurrence, and often requires a complex mix of treatments. Comprehensive approaches to treating this affective disorder may include lifestyle interventions, therapy sessions, and the use of medications. In more difficult cases, electroconvulsive therapy, where electrical currents are sent through the brain, can be used to alleviate the symptoms of depression[1].

Increasingly, studies have examined the use of omega-3 polyunsaturated fatty acids (n-3) to treat depression. A link between n-3s and depression was suggested after the recognition of a population-wide reduction in Western dietary intakes of omega-3s[2] being correlated with[3] an increase in rates of depression. Some randomized controlled trials have shown benefits for symptoms of MDD[4] among those who supplemented with n-3s.

The positive effects of n-3s on depression are thought to occur as a result of alterations to the cell membrane, cell to cell communication, and on inflammatory processes and neurotransmitter activity. These processes[5] have all been implicated in the pathology of MDD[6].

However, not all investigations[7] have reported beneficial effects and previous meta-analyses have found considerable variability[8] among studies. The present study is the fourth update to the Cochrane Collaboration’s review on omega-3 fatty acids for depression. To help reduce the variability seen in other reviews, this meta-analysis focuses solely on MDD in adults, not taking into account other types of depressive disorders or younger populations. The objective of this review was to assess the effects of n-3s versus a comparator (e.g. a placebo or standard antidepressant treatment). To do this, the authors pool the results from multiple intervention studies and statistically analyze the data to see if there was a positive, negative, or neutral overall result.

Depression affects over 350 million people worldwide. Major depressive disorder (MDD) is defined as a state of extreme unhappiness and an inability to feel pleasure lasting at least two weeks. This meta-analysis examines the efficacy of n-3s versus placebo or standard depression treatment to alleviate the symptoms of MDD in adults.

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