ALLERGIC RHINITIS MAY BE ASSOCIATED WITH PARKINSON'S DISEASE

Allergic rhinitis and other diseases of immediate-type hypersensitivity may be significantly associated with later development of Parkinson’s disease, according to James Bower, MD, and colleagues. Their report was published in the August 8 Neurology.

Researchers included 196 patients with onset of Parkinson’s disease from 1976 to 1995 and 196 matched controls; the median age at onset of the disorder was 71. Frequency of asthma, allergic rhinitis, and hay fever was significantly higher in patients with Parkinson’s disease than in controls. This association was stronger for women and for patients with earlier onset of Parkinson’s disease, but the differences did not reach statistical significance, the investigators noted. When the diseases were considered separately, the association remained significant for allergic rhinitis but not for hay fever and asthma. Both NSAIDs and steroidal treatment were used less frequently in Parkinson’s disease patients than in controls, although this was a nonsignificant association. In addition, there was no association between aspirin use and later development of Parkinson’s disease.

Dr. Bower and colleagues posited that despite the current lack of definitive evidence showing a role for antibodies against the brain in the etiology of Parkinson’s disease, patients with diseases of immediate-type hypersensitivity may be predisposed to initiate inflammatory responses. The fact that these patients are "genetically predisposed to initiate a humoral response to low levels of antigens" is a reason for this hypothesis, the researchers stated.

Additionally, although a significant association between preceding asthma and Parkinson’s disease was not found, "asthma is a heterogeneous pathologic entity with some patients suffering from an IgE [immunoglobulin E]–mediated allergic asthma, and others suffering from a non–IgE-mediated idiosyncratic asthma," induced by factors such as stress and exercise, Dr. Bower’s team noted.

"Low occurrence of immunologic disease and the resulting limited power" may explain why no association between other immunologic diseases and Parkinson’s disease was found. Another possible explanation is that patients took anti-inflammatory drugs for prolonged periods of time, which resulted in an opposing effect. Dr. Bower and colleagues noted that since "allergic rhinitis is usually not treated with NSAIDs or systemic steroids, one would not expect to see the compensatory effect of treatment in that population."

The researchers summarized, "Because IgE antibodies play a pathogenic role in diseases of immediate-type hypersensitivity, our results may support the hypothesis that there is an inflammatory component in the pathogenesis of Parkinson’s disease."

Suggested Reading
Bower JH, Maraganore DM, Peterson BJ, et al. Immunologic diseases, anti-inflammatory drugs, and Parkinson disease: a case-control study. Neurology. 2006;67:494-496.

NO LINK FOUND BETWEEN ASPIRIN AND STROKE SEVERITY

Prior aspirin use appears to have no effect on stroke type or severity, as reported by Stefano Ricci, MD, and colleagues in the July Stroke.

During the three days before randomization in the International Stroke Trial, researchers assessed aspirin use in 17,850 patients with ischemic stroke. Prior aspirin use was reported in 3,820 (21.4%) participants. In univariate analyses, previous aspirin use appeared to be associated with greater baseline stroke severity, more severe stroke syndrome, and in control subjects, worse observed outcome at six months. After adjustment, however, none of these associations was significant. These findings "suggest that previously reported positive and negative associations may well have been attributable to the play of chance in small samples, confounding or other biases, rather than a biological effect of aspirin," said Dr. Ricci.

The researchers pointed out several strengths in their study compared with previously published reports on the effect of antiplatelet use on stroke severity. The chance of random error and extreme effects in small samples was limited due to a sample size larger than all the other previous studies put together, and biases in data collection and attrition were also limited due to prospectively collected data that were "very complete."

As a result of the large number of patients in their analysis, associations found between stroke severity and prior aspirin use in the univariate analyses were statistically highly significant, but "probably of limited clinical significance," the researchers stated, because the odds ratios "were close to unity and the difference of means similarly small. Furthermore, the fact that the association disappeared after adjusting for confounding factors confirmed that any apparent relationship of previous aspirin treatment with greater stroke severity was probably not a biological effect but merely attributable to confounding."

Lack of an association between prior aspirin use and ischemic stroke was observed both at baseline and at six-month follow-up, Dr. Ricci and colleagues concluded.

Suggested Reading
Ricci S, Lewis S, Sandercock P, et al. Previous use of aspirin and baseline stroke severity: an analysis of 17,850 patients in the International Stroke Trial. Stroke. 2006;37:1737-1740.

MIGRAINE WITH AURA ASSOCIATED WITH INCREASED CARDIOVASCULAR DISEASE RISK

A history of migraine with aura in women 45 or older may be associated with an increased risk of major cardiovascular disease, as reported in the July 19 JAMA.

Tobias Kurth, MD, ScD, and colleagues evaluated data from 27,840 women 45 or older who were without cardiovascular disease or angina at study entry. At baseline, 5,125 women (18.4%) reported a history of migraine. Among 3,610 participants with migraine in the prior year (classified as active migraine), 1,434 (39.7%) reported symptoms of aura. Five hundred eighty major cardiovascular events occurred during a mean 10 years of follow-up. Women who reported active migraine with aura had multivariable-adjusted hazard ratios of 2.15 for major cardiovascular disease, 1.91 for ischemic stroke, 2.08 for myocardial infarction, 1.74 for coronary revascularization, 1.71 for angina, and 2.33 for ischemic cardiovascular disease death, compared with women with no history of migraine.

In addition, following adjustment for age, there were 18 further major cardiovascular events attributable to migraine with aura per 10,000 women per year. However, no increased risk of any ischemic vascular events or angina in women who reported active migraine without aura was observed.

Dr. Kurth and colleagues offered several explanations for the association between migraine with aura and subsequent overall and specific ischemic vascular events. The researchers pointed out that migraine with aura has been previously linked to "elevated cholesterol levels, higher blood pressure, higher likelihood of hypertension, and increased Framingham risk score for coronary heart disease." Because thromboembolic events do not cause coronary stenosis and angina, the investigators’ findings may indirectly support the hypothesis that "migraine with aura identifies women at increased risk of progressive atherosclerosis and subsequent vascular events," Dr. Kurth’s team noted. "However, the increased risk of any evaluated vascular event remained after controlling for a large number of cardiovascular risk factors."

"Since migraine without aura is far more common than migraine with aura, our data demonstrate no increased risk of cardiovascular disease for the majority of migraine patients," Dr. Kurth’s research team concluded. "Future research should focus on a better understanding of the relationship between migraine, aura status, and cardiovascular events."

Suggested Reading
Kurth T, Gaziano JM, Cook NR et al. Migraine and risk of cardiovascular disease in women. JAMA. 2006;296:283-291.

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