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zoom RSS 多発性硬化症の季節変動

<<   作成日時 : 2010/09/01 20:27   >>

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 多発性硬化症の症状の強さは季節により変動するという。脳スキャンで見ると春と夏に悪化する。病変所見は春から夏にかけて3倍以上も出現していたという。
 温度と太陽放射solar radiation が関連しているという。

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31 August 2010 Last updated at 00:01 GMT
MS activity alters with seasons, US researchers say

画像The severity of multiple sclerosis (MS) may change with the seasons, say US researchers.

Brain scans of patients compared with weather patterns at the time showed higher levels of disease activity in the spring and summer.

The US researchers said the findings had implications for testing new medicines, which may show up different results depending on the time of year.

It is not clear why warmer weather would have this effect.

Other studies have shown that vitamin D from exposure to sunlight may have a protective effect against MS - a long-term inflammatory condition of the central nervous system.

For the study, researchers compared MRI brain scans of 44 people taken from 1991 to 1993 to daily temperature, solar radiation and precipitation measurements over the same time.

The adults in the study, who had untreated MS, had eight weekly scans followed by eight scans every fortnight then six monthly check-ups - an average of 22 scans per person.

After one year, 310 new brain lesions were found in 31 people, they reported in Neurology.

The lesions were up to three times more likely to appear in the warmer spring and summer months.

Further analysis also showed that there was a link between both new disease activity and intensity of disease activity and the warmer months.
Trial results

Study leader Dr Dominik Meier, from Brigham and Women's Hospital in Boston, said: "Not only were more lesions found during the spring and summer seasons, our study also found that warmer temperatures and solar radiation were linked to disease activity."

He pointed out that clinical trials often use MRI (magnetic resonance imaging) to assess the effectiveness of a drug and studies commonly last between six and 12 months, which may have implications for how effective a new medication seems.

In an accompanying editorial Dr Anne Cross, from Washington University School of Medicine, added: "This is an important study because it analyses records from the early 1990s, before medications for relapsing MS were approved, so medicines likely could not affect the outcome.

"Future studies should further explore how and why environmental factors play a role in MS."

Dr Susan Kohlhaas, research communications officer at the MS Society, said more research was needed.

But added: "This small study is intriguing and, if validated in larger studies, has the potential to influence the way clinical trials are designed."

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NEUROLOGY 2010;75:799-806
© 2010 American Academy of Neurology
Seasonal prevalence of MS disease activity
D.S. Meier, PhD, K.E. Balashov, MD, B. Healy, PhD, H.L. Weiner, MD and C.R.G. Guttmann, MD

From the Center for Neurological Imaging (D.S.M., C.R.G.G.), Brigham & Women's Hospital, Boston, MA; Robert Wood Johnson Medical School (K.E.B.), New Brunswick, NJ; and Partners Multiple Sclerosis Center (B.H., H.L.W.), Brigham & Women's and Massachusetts General Hospitals, Boston, MA.

Address correspondence and reprint requests to Dr. Dominik S. Meier, Center for Neurological Imaging, Brigham & Women's Hospital, 221 Longwood Avenue, RF396, Boston, MA 02115 meier@bwh.harvard.edu

Objective: This observational cohort study investigated the seasonal prevalence of multiple sclerosis (MS) disease activity (likelihood and intensity), as reflected by new lesions from serial T2-weighted MRI, a sensitive marker of subclinical disease activity.

Methods: Disease activity was assessed from the appearance of new T2 lesions on 939 separate brain MRI examinations in 44 untreated patients with MS. Likelihood functions for MS disease activity were derived, accounting for the temporal uncertainty of new lesion occurrence, individual levels of disease activity, and uneven examination intervals. Both likelihood and intensity of disease activity were compared with the time of year (season) and regional climate data (temperature, solar radiation, precipitation) and among relapsing and progressive disease phenotypes. Contrast-enhancing lesions and attack counts were also compared for seasonal effects.

Results: Unlike contrast enhancement or attacks, new T2 activity revealed a likelihood 2–3 times higher in March–August than during the rest of the year, and correlated strongly with regional climate data, in particular solar radiation. In addition to the likelihood or prevalence, disease intensity was also elevated during the summer season. The elevated risk season appears to lessen for progressive MS and occur about 2 months earlier.

Conclusion: This study documents evidence of a strong seasonal pattern in subclinical MS activity based on noncontrast brain MRI. The observed seasonality in MS disease activity has implications for trial design and therapy assessment. The observed activity pattern is suggestive of a modulating role of seasonally changing environmental factors or season-dependent metabolic activity.

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