Patients
with increased inflammation, including those receiving cytokines for medical
treatment, have a greatly increased risk of depression. For example, a 6-month
treatment course of interferon-alpha therapy for chronic hepatitis C virus
infection causes depression in approximately 30% of patients.
Omega-3
fatty acids, more commonly known as fish oil, have a long list of health
benefits, including lowering the risk of heart disease and reducing
triglyceride levels. These nutritional compounds are also known to have
anti-depressant and anti-inflammatory properties.
Despite
some recent negative findings, as their tendency to increase the risk for
prostate cancer was proven and some of the putative health benefits were not
replicated in large trials, omega-3's remain of high interest to the depression
field, where several studies have suggested benefits for depression and other
psychiatric disorders.
This
led a group of international researchers, led by senior author Dr. Carmine
Pariante, to conduct a randomized, double-blind, placebo-controlled study in
order to carefully evaluate the effects of omega-3 fatty acids on
inflammation-induced depression.
They
recruited 152 patients with hepatitis C to participate, each of whom was
randomized to receive two weeks of treatment with EPA, DHA, or placebo. EPA
(eicosapentaenoic acid) and DHA (docosahexaenoic acid) are the two main omega-3
fatty acids in fish oil supplements.
Following
the two-week treatment, the patients received a 24-week course of
interferon-alpha treatment and were evaluated repeatedly for depression.
The
researchers found that treatment with EPA, but not DHA or placebo, decreased
the incidence of interferon-alpha-induced depression in patients being treated
for hepatitis C.
Pariante,
a Professor at the Institute of Psychiatry, Psychology & Neuroscience at
King's College London, added, "The study shows that even a short course
(two weeks) of a nutritional supplement containing one such omega-3
polyunsaturated fatty acid (EPA) reduced the rates of new-onset depression to
10%."
In
addition, both EPA and DHA delayed the onset of depression, and both treatments
were well tolerated, with no serious side effects.
"These
new data provide promising support for omega-3 fatty acids to prevent
depression, complementing other studies where omega-3's were found to enhance
antidepressant treatment," said Dr. John Krystal, Editor of Biological
Psychiatry.
EPA
is considered an "endogenous" anti-inflammatory, and in previous
work, also published in Biological Psychiatry, these same authors found
that subjects with low levels of endogenous EPA in the blood were at higher
risk of developing depression. Therefore, the authors speculate that this
nutritional intervention restores the natural protective anti-inflammatory
capabilities of the body, and thus protects patients from new-onset depression
when inflammation occurs.
Although
further work is still necessary and the findings must be replicated, these data
indicate that omega-3 polyunsaturated fatty acids may be effective in
preventing depression in a group of patients at high-risk of depression because
of increased inflammation.
The
article is "Omega-3 Fatty Acids in the Prevention of
Interferon-Alpha-Induced Depression: Results from a Randomized, Controlled
Trial" by Kuan-Pin Su, Hsueh-Chou Lai, Hui-Ting Yang, Wen-Pang Su,
Cheng-Yuan Peng, Jane Pei-Chen Chang, Hui-Chih Chang, and Carmine M. Pariante
(doi: 10.1016/j.biopsych.2014.01.008). The article appears in Biological
Psychiatry, Volume 76, Issue 7 (October 1, 2014), published by Elsevier.
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