From Medscape Education Clinical Briefs

Low Levels of DHA Associated With Increased Suicide Risk CME

News Author: Deborah Brauser
CME Author: Désirée Lie, MD, MSEd

Authors and Disclosures

CME Released: 09/06/2011; Valid for credit through 09/06/2012

Clinical Context

According to the current study by Hibbeln and colleagues, suicide rates among active-duty US military personnel have increased to record numbers. Also, other than the extreme stress of deployment, other factors may predispose to suicide. Deficiencies in nutrients for brain function may account for susceptibility to suicide. Reduced levels of the omega-3 essential highly unsaturated fatty acids (n-3 HUFAs), in particular, docosahexaenoic acid (DHA), have been shown to be associated with increased suicide risk among civilian populations. The American Psychiatric Association already recommends consumption of at least 1 g per day of n-3 HUFAs for all patients with psychiatric disorders, and the US Food and Drug Administration has determined that up to 3 g per day of n-3 HUFAs is safe.

This is a case-controlled study comparing 800 military personnel with completed suicides vs matched control participants to examine the association between DHA and other fatty acid levels and the risk for suicide.

Study Synopsis and Perspective

Low levels of DHA, the major omega-3 fatty acid concentrated in the brain, may increase suicide risk, new research suggests.

A retrospective case-control study of 1600 United States military personnel, including 800 who had committed suicide and 800 healthy counterparts, showed that all participants had low omega-3 levels. However, the suicide risk was 62% greatest in those with the lowest levels of DHA.

Our findings add to an extensive body of research that points to a fundamental role for DHA and other omega-3 fatty acids in protecting against mental health problems and suicide risk.

"Our findings add to an extensive body of research that points to a fundamental role for DHA and other omega-3 fatty acids in protecting against mental health problems and suicide risks," co–principal investigator Capt. Joseph R. Hibbeln, MD, acting chief, Section on Nutritional Neurosciences at the National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland, said in a statement.

Dr. Joseph R. Hibbeln

He told Medscape Medical News that the US military "goes to great steps" to ensure they provide the best nutrition to their soldiers, especially in combat and deployment situations. However, these findings on the potential usefulness of omega-3 fatty acids for the brain should be taken into account when designing military diets in the future.

"Omega-3 is already recommended by the American Psychiatric Association as adjunctive therapy for anybody with a psychiatric disorder, especially for those with major depression," said Dr. Hibbeln.

When asked whether he would recommend omega-3 even to those without a diagnosis, Dr. Hibbeln replied, "it certainly wouldn't hurt."

"It's best not to categorize this as 'a drug,' but instead as a fundamental nutrient."

The study was published online August 23 in the Journal of Clinical Psychiatry.

Largest Study of Its Kind

"The recent escalation of U.S. military suicide deaths to record numbers has been a sentinel for impaired force efficacy and has accelerated the search for reversible risk factors," write the investigators.

They note that suicide rates in military personnel have doubled since the start of Operation Enduring Freedom and Operation Iraqi Freedom, and now "rival the battlefield in toll."

Previous research has shown that n-3 HUFAs, especially DHA, are needed for optimal neural function.

Nutritional deficiencies in n-3 HUFAs may increase vulnerability to combat deployment stress, manifesting as psychiatric symptoms including adjustment disorders, major depression, impulsive violence, and suicide.

"Nutritional deficiencies in n-3 HUFAs may increase vulnerability to combat deployment stress, manifesting as psychiatric symptoms including adjustment disorders, major depression, impulsive violence, and suicide," the investigators write.

In addition, observational studies conducted in civilian populations have suggested that low DHA levels are linked to increased risk for suicide attempt and may contribute to adverse psychiatric symptoms.

For this study, prospectively collected blood samples from the Armed Forces Health Surveillance Center were evaluated from 800 suicide deaths (95.6% men; mean age, 27.3 years) and 800 randomly selected age- and sex-matched healthy control participants. All were active-duty personnel from the Army, Navy, Air Force, and Marines who served from 2002 to 2008.

"To our knowledge, this is the largest study of biological factors among suicide deaths," the authors write.

The Armed Forces Health Surveillance Center also maintains matched health data, including postdeployment health assessment questionnaires and International Statistical Classification of Diseases, Ninth Revision, mental health and substance abuse diagnosis reports.

Higher Suicide Risks

Results showed that "each standard deviation [SD] of lower DHA was associated with a 14% greater risk for suicide (odds ratio [OR], 1.14; 95% confidence interval [CI], 1.02-1.27; P < .03)," report the investigators.

Men who had serum DHA levels below 1.75% had a significantly greater risk of completing suicide than men with higher levels (adjusted OR, 1.62; 95% CI, 1.12 - 2.34; P < .01.)

There was also a 52% higher suicide risk for all participants who reported having witnessed fellow soldiers wounded, killed, or dead (OR, 1.52; 95% CI, 1.11 - 2.09; P < .01).

In addition, there was an increased risk for suicide associated with more inpatient mental health visits (OR, 1.47; P < .001). However, it was not associated with any substance abuse diagnosis.

Although women had a significantly higher mean DHA percentage compared with men (1.48% vs 1.15%), there was no difference in fatty acids found between the women who did and those who did not complete suicide.

"Nearly all US military personnel had low n-3 HUFA status in comparison to North American, Australian, Mediterranean, and Asian populations," write the researchers.

"Although these data suggest that low serum DHA may be a risk factor for suicide, well-designed intervention trials are needed to evaluate causality," they add.

Dr. Janice Kiecolt-Glaser

The treatment committee for the American Psychiatry Association, of which Dr. Hibbeln was a member, issued recommendations in 2006 for 1 g/day of n-3 HUFAs for anyone with a psychiatric disorder, and the US Food and Drug Administration has determined that up to 3 g/day is considered safe.

Omega-3 Intake Matters

"I thought this was an impressive study with a very large sample size," Janice Kiecolt-Glaser, PhD, professor of psychiatry and psychology and S. Robert David Chair of Medicine at the Institute for Behavioral Medicine Research at Ohio State University College of Medicine in Columbus, told Medscape Medical News.

It suggests that the diet of our military, in terms of omega-3 intake, is poor and that it could have implications for mental health. And that's an important and cautionary note for all of us.

"It suggests that the diet of our military, in terms of omega-3 intake, is poor, and that it could have implications for mental health. And that's an important and cautionary note for all of us," said Dr. Kiecolt-Glaser, who was not involved in the study.

As recently reported by Medscape Medical News, Dr. Kiecolt-Glaser led a trial showing that omega-3 supplements may lower both anxiety symptoms and proinflammatory cytokines in healthy young adults.

Dr. Kiecolt-Glaser said she was surprised at how low the omega-3 intake was overall in the current study. "Given this is a population that's already under a lot of strains and at risk for depression, it's something that really needs attention."

She noted that Dr. Hibbeln "has become Mr. Omega-3 for a lot of the psychiatric literature," in terms of depression and omega-3 use.

"He's done cross-national studies in a variety of different cohorts that showed repeatedly that depression is associated with lower levels of omega-3. Then, in randomized controlled trials, we see that omega-3 intake has beneficial effects," she reported.

On the basis of the results of this study, said Dr. Kiecolt-Glaser, it's a "no brainer" to investigate whether making dietary improvements in military personnel makes a difference to mental health outcomes.

"For clinicians who treat civilians, I'd say that omega-3 intake matters, and that it's helpful to keep in mind that there might be dietary issues related to depression as well."

The study was supported by a grant from the Defense Advanced Research Projects Agency and by the Division of Intramural Basic and Clinical Research at the National Institute on Alcohol Abuse and Alcoholism. The study authors and Dr. Kiecolt-Glaser have disclosed no relevant financial relationships.

J Clin Psychiatry. Published online August 23, 2011. Abstract

Study Highlights

• The study compared total serum fatty acid compositions from among 800 randomly selected active-duty US military suicide deaths vs 800 matched control participants between 2002 and 2008.
• The Armed Forces Health Surveillance Center is a repository with more than 40 million samples of serum with matched health data from US military personnel.
• Postdeployment data obtained within 6 months of completion of the last deployment were used to determine stressors during deployment; self-report of mental health status; referral to mental health services; and International Classification of Diseases, Ninth Revision, Clinical Modification, diagnoses.
• 800 suicide deaths were identified through active-duty service records from members of the Army, Navy, Air Force, and Marines.
• Cases were included if declared as suicide officially, and index date was the date of serum obtained close to the suicide death.
• All case patients had serum collected within 12 months of the suicide.
• Control participants were randomly selected by the Armed Forces Health Surveillance Center and were matched by age, sex, rank, and availability of sera within 12 months.
• International Classification of Diseases discharge diagnoses for hospitalizations and ambulatory visits were provided by the Armed Forces Health Surveillance Center database for case patients and control participants.
• For case patients, age at death ranged from 17 to 59 years (mean, 27.3 years; SD, 7.3 years).
• Ethnicity and branch of service influenced the data; these were controlled for in analysis.
• Levels of DHA were very low among all personnel.
• Almost all control participants had been deployed (99.1%) vs only 61.9% of case patients.
• In the analysis, each SD of lower DHA level was associated with a 14% increased risk for suicide (OR, 1.14 [95% CI, 1.02 - 1.27] after adjustment for ethnicity and service component).
• When patients were examined by octiles of DHA level, women were found to have higher DHA levels than men.
• However, only 4.4% of the total sample were women (n = 70).
• Only patients with the highest level of DHA were protected from the risk for suicide.
• Overall suicide risk was 62% higher among men with low DHA status vs those with high DHA status (OR, 1.62; 95% CI, 1.12 - 2.34; P < .01).
• This finding compares with an increased risk of 52% (OR, 1.52; 95% CI, 1.11 - 2.09; P < .01) for exposure to combat trauma (report of seeing wounded, killed, or dead coalition personnel during deployment) for the risk for suicide.
• In the lowest octile, the OR was 1.75, followed by 1.52 in the second, 1.67 in the third, 1.57 in the fourth, 1.57 in the fifth, and 1.77 in the sixth octile.
• The risk was not increased for those in the seventh octile of DHA level.
• Lower levels of 2 other fatty acids, stearic acid and dihomo-γ-linoleic acid, were also associated with an increased risk for suicide.
• Higher levels of palmitoleic acid and cis-vaccenic acid were associated with a protective effect on the risk for suicide.
• Lower levels of eicosapentaenoic acid and arachidonic acid were not associated with suicide risk.
• The risk was higher for case patients for responses involving exposure to combat death.
• Suicide case patients were also more likely to have had inpatient mental health visits (OR, 1.47 per increased SD; P < .001).
• However, a history of substance abuse was not associated with increased suicide risk, and low DHA levels were not associated with either mental health visits or substance abuse diagnoses.
• The authors concluded that US military personnel had low levels of DHA overall and that the low levels predisposed to suicide risk at a magnitude as high as the impact of seeing wounded, killed, or dead coalition personnel.
• They recommended that the US military consider evaluation of 3-n HUFA status among US military personnel and possible supplementation as a suicide prevention strategy.

Clinical Implications

• Among US military personnel, low DHA levels are associated with an increased risk for suicide.
• Other risk factors for suicide include low levels of stearic and palmitoleic acids, cis-vaccenic acid, and dihomo-γ-linoleic acid; and a higher number of mental health visits.

CME Test

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CME Information

CME Released: 09/06/2011; Valid for credit through 09/06/2012

Target Audience

This article is intended for primary care clinicians, psychiatrists, military medicine specialists, and other specialists who care for military personnel.

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1. Describe the association between low serum docosahexaenoic acid levels and the risk for suicide among active US military personnel.
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According to your Medscape profile, you will be issued Letter of Completion for this activity. If this is incorrect, please edit your profile

Medscape, LLC is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to provide continuing medical education for physicians.

Medscape, LLC designates this enduring material for a maximum of 0.25 AMA PRA Category 1 Credit(s)™ . Physicians should claim only credit commensurate with the extent of their participation in the activity.

This activity, Medscape Education Clinical Briefs has been reviewed and is acceptable for up to 300 Prescribed credits by the American Academy of Family Physicians. AAFP accreditation begins September 1, 2010. Term of approval is for 1 year from this date. Each issue is approved for .25 Prescribed credits. Credit may be claimed for 1 year from the date of this issue.

Note: Total credit is subject to change based on topic selection and article length.

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