May 6, 2008 (Washington, DC) — Analysis of a major population-based study of mental health suggests an association between allergies and suicidality.
Using data from the National Comorbidity Survey Replication (NCS-R), researchers showed a significant association between allergies and a history of suicide ideation and between allergies and a history of suicide attempts that remained significant even after they controlled for depression.
"This is similar to previous results showing significant relationships between both asthma and dermatitis and suicide ideation and suicide attempts," the researchers, with coauthor Stephen Welch, MD, from the Medical College of Georgia, in Augusta, write.
Their report was presented here at the American Psychiatric Association 161st Annual Meeting.
History of Allergies and Suicide Ideation
The study used data from the NCS-R, a national representative sample of 9882 English-speaking people aged 18 years or older living in US households between 2001 and 2004, funded by the National Institute of Mental Health.
Part 1 of the survey, comprising the core diagnostic assessment, was administered to all respondents, and Part 2 only to those individuals who met lifetime criteria for a Part 1 disorder, as well as a probability sample of other respondents.
Logistic regression models were used to calculate adjusted odds ratios with 95% confidence intervals after researchers controlled for confounding variables, including age, sex, race, and a history of depression.
Their results showed a positive and significant correlation between a history of allergies and suicidal ideation, with an adjusted odds ratio of 1.37 (95% CI, 1.13 – 1.65), they note. After they controlled for depression, the odds ratio was 1.27 (95% CI, 1.04 – 1.54).
The correlation with a history of suicide attempts was even greater, with an adjusted odds ratio of 1.40 (1.07 – 1.84), falling to 1.32 (1.003 – 1.74) after they controlled for depression.
The researchers postulate several different theories on the association, Dr. Welch told Medscape Psychiatry. "Is this just a quality-of-life issue? Is this something to do with personality? Or is there a biochemical basis behind it?" he said.
Previous studies that looked at whether personality traits might simply lead some people to be more likely to report both depression and allergies did not find a correlation, according to the paper. Nor did a study of possible association between increased levels of immunoglobulin E (IgE), the authors write.
"The most promising research seems to be with increased cytokine activity in the body," said Dr. Welch. Research is looking at their possible relationship to depression. Other studies have shown increased cytokine levels in the brains of suicide victims.
Future Research
Right now, Dr. Welch said of the allergy-suicidality link they are reporting here: "It's not a major correlation, so it would be unlikely that this would be of big clinical significance, in terms of: 'Do I need to screen for allergy when I am in the emergency room assessing someone for suicidality?'
"There are more important risk factors that have a much greater level of significance, such as a history of depression, history of previous attempts," he explained.
However, he said, if research can look at homogeneous groups of people — for example, groups of the same sex, age, race, and history of previous illness — to limit the number of variables that could be influencing the situation, "We would hope that that would give us a lot more insight into what is going on, and it would give us a good place to start attacking in terms of how can we treat this effectively."
Questions for future research, saidWelch, include whether the association would remain significant if the data were controlled for other illnesses, including asthma.
In addition, he said, longitudinal studies looking at severity of symptoms might provide further support. "If you find that as allergy symptoms increase, the intensity of suicide ideation, the number of attempts, increases, that would lend evidence to the allergies causing the suicidality," Dr. Welch added.
Some work, he noted, does indicate that peaks in tree pollen correlate with certain types of suicide attempts. If suicide attempts go down with treatment for asthma and allergy symptoms, "that would also lend some more credence," he added.
Future research for his group, he said, may include looking at the data while controlling for asthma and some of the other Axis I disorders.
The study was supported by the National Institute of Mental Health.
American Psychiatric Association 161st Annual Meeting: Abstract NR2-030. Presented May 5, 2008.
Medscape Medical News © 2008 Medscape
Cite this: Kathryn Foxhall. Research Finds Possible Link Between Allergies and Suicidality - Medscape - May 06, 2008.
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