Omega-3
Fatty Acids and Depression
by
Morten Bryhn, MD, Ph D
10/31/2002
Mental depression is common
affecting 8-10% of the population at any time. There is
a need for the individual to take own responsibility for
the disease, in the prevention of relapse after a mild depression.
Secondary prevention of depressive disease is important
and omega-3 fatty acids seem to have anti depressive effects.
Mental depression is very common affecting 8-10% of the
population at any time. Statistics show that the prevalence
of major depression has increased and the age of onset has
decreased in every decade during the 2000 century in the
Western World. Anti-depressive medication is on the top
list of social expenditure for drugs in many countries.
But even if proven effective there is a need for the individual
to take own responsibility for the disease, especially in
the prevention of relapse after a mild depression. Secondary
prevention of depressive disease must be based on psychotherapy
to give the patient insight into which mechanisms that can
lead to depression in the individual case. But there may
also be complementary ways of increasing the effects of
non-pharmacological prevention.
St John's
wort has been used for centuries in the treatment of mood
disorders. Food supplement products containing this wort
are extensively used especially in Central Europe for the
prevention and treatment of mild depression. Controlled
studies have shown positive effects similar to anti-depressive
drugs (1). Omega-3 fatty acids from fish seem to have similar
effects. In a study comparing fish intake and rate of depression
in 9 countries, an inverse relationship was found between
annual fish consumption per capita and the percentage of
the population having the diagnosis major depression (2).
A population
study of 3 204 adults in Finland revealed that those with
frequent intake of fish were less susceptible to having
depressive symptoms compared to the group of infrequent
fish consumers (3). In Island people usually don't experience
winter depressions, which is very frequent in Canada (4).
Living on the same latitude the diets of these two populations
are very different with the Islanders eating fish several
times per week.
Along
the same line a population study from the US examining the
prevalence of depression after delivery demonstrated that
low seafood consumption increased the risk of having depression
(5). In fact patients with major depression usually have
low levels of omega-3 fatty acids in blood analysis (6).
Fatty
fish contains the two fatty acids eicosapentaenoic acid
(EPA) and docosahexaenoic acid (DHA). DHA and to a lesser
extent EPA are important components of brain structures.
DHA seems to be a structural
Serotonin
is an import neurotransmitter and the thinking today is
that either reduced production of serotonin and/or reduced
number of serotonin receptors in the post-synapses may lead
to depressive disorders. Serotonin is produced and stored
in synaptic vessels and released upon stimulation by electrical
impulses conducted along the neuron. Binding to post-synaptic
receptors, serotonin change conduction capacity of impulses
on site. Modern anti-depressive drugs (like Prozac) are
preventing re-absorption of serotonin in the synaptic cleft
compensating for reduced production of serotonin or presentation
of serotonin receptors.
The
mode-of-action of EPA on structures in the synaptic cleft
or the serotonin system is not known. However, two controlled
studies in patients with major depression have demonstrated
interesting results. Andrew Stoll and colleagues (11) allocated
30 patients with manic-depressive disease to treatment with
high doses of omega-3 fatty acids or placebo. The patients
were in a state of remission induced by standard pharmacological
treatment and they were followed and controlled for reappearance
of symptoms. After an observation period of 4 months significantly
more patients in the omega-3 treated group were still in
remission compared to the placebo group. Positive effects
of omega-3 fatty acids were recorded not only for depressive
symptoms but also for mania.
A second
study from Israel (12) recruited 20 patients with major
depressive disease. They were all in remission on standard
anti-depressive medication. The group was divided in two:
one group given omega-3 fatty acids and the other placebo.
The patients were followed for only 4 weeks but at that
time significantly more patients in the placebo group had
experienced depressive symptoms according to a standardized
method.
At the
present time studies are ongoing examining the effects of
omega-3 fatty acids on depression after delivery, in alcoholics,
and in patients with manic-depressive disease. The results
of these studies will provide evidence for or against using
omega-3 fatty acids in the treatment of depression. If proven
effective in these patient's omega-3 fatty acids could be
tried also for treatment and prevention of minor depressive
disease. Maybe soon omega-3 fatty acids will be used as
St John's wort is used today for self-treatment of minor
depressive symptoms. While waiting for the results of new
studies we should all increase our intake of fatty fish
or take omega-3 food supplements for the potential benefit
of our mental health. This has been advocated by Dr Stoll
first demonstrating the beneficial effects of omega-3 fatty
acids in depressive patients and who has published a book
on this topic (13).
REFERENCES
1. Linde K, et al. St John's wort for depression ? an overview
and meta-analysis of randomised clinical trials. BMJ 1996;313:253-258
2. Hibbeln JR. Fish consumption and major depression. The
Lancet 1998;351:1213-1215
Tanskanen A,et al. Fish consumption and depressive symptoms
in the general population in Finland. Psychiatric Services
2001;52:529-531
3. Magnusson A, et al. Lack of seasonal mood change in the
Islandic population: results of a cross-sectional study.
Am J Psychiatry 2000;157:234-238
4. Hibbeln JR. Seafood consumption, the DHA content of mother's
milk and prevalence rates of postpartum depression: a cross-national
ecological analysis. J of Affective Disorders; in press
2001
5. Maes M, et al. Fatty acid composition in major depression.
J Affective Disorders 1996;38:35-46
6. Söderberg M, et al. Fatty acid composition of brain
phospholipids in aging and in Alzheimer's disease. Lipids
1991;26:421-425
7. Conquer JA, et al. Fatty acid analysis of blood plasma
of patients with Alzheimer's disease, other types of dementia,
and cognitive impairment. Lipids 2000;35:1305-1312
8. Peet M, et al. Two double-blind placebo-controlled studies
of EPA in the treatment of schizophrenia. Schizophrenia
Research 2001;49:243-251
9. Emsley R, et al. Randomized, placebo-controlled study
of ethyl-EPA as supplemental treatment in schizophrenia.
Am J Psychiatry 2002;159:1596-1598
10. Stoll AL, et al. Omega-3 fatty acids in bipolar disorder.
Arch Gen Psychiatry 1999;56:407-412
11. Nemets B, et al. Addition of omega-3 fatty acid to maintenance
medication treatment for recurrent unipolar depressive disorder.
Am J Psychiatry 2002;159:477-479
Stoll AL. The omega-3 connection. Simon & Schuster NY
2001
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