すっきり目覚めているのはカフェインのおかげ?

 すっきり目覚めているのはカフェインのおかげというわけではない。
画像 16人のカフェイン常用者を2グループに分け、一方は1日400mgのカフェイン(20オンスの濃いコーヒーに相当)を3週間服用し、他方はプラセーボを3週間服用し、その後グループを交代した。
 切り替えで脳血流と脳波に急激な変化が起き、プラセーボに切り替わると頭痛が出現し、活気や注意力が減退した。しかし、維持期には両者で大きな相違は見られなかった。カフェインを消費する唯一の明白な利点は、それが禁断症状を防止したということだった。
 耐性が出現し、何の利益も得られなくなる。しかしコーヒーを飲むのを止めようとは思わない。
-----------------------------------------------------
Patterns: It May Not Be Caffeine Keeping You Awake
http://www.nytimes.com/2009/05/12/health/research/12patt.html
By NICHOLAS BAKALAR
Published: May 11, 2009

You may not need that cup of coffee. A study has found that once people get through caffeine withdrawal ― terrible headaches, among other unpleasantness ― they feel just as wide-awake on a placebo as they do on caffeine.

The scientists divided 16 regular caffeine users into two groups. One group was maintained for three weeks on 400 milligrams of caffeine a day (about the amount in 20 ounces of strong coffee) and the other spent three weeks on a placebo. Then the groups were switched.

Switching to either placebo or caffeine caused sharp changes in blood flow to the brain and encephalography readings, and those who switched to placebo had headaches and decreases in energy and alertness.

But there were no significant differences between the two maintenance periods ― that is, whether the person consistently consumed caffeine or placebo, most physiological measures, and all subjective measures of alertness or tiredness were identical.

The only apparent benefit of consuming caffeine was that it prevented the withdrawal symptoms. The study appears in Psychopharmacology.

The lead author, Stacey Sigmon, a research associate professor of psychiatry at the University of Vermont, suggests that habitual caffeine users may be deceiving themselves. “Tolerance develops,” she said, “and you’re not getting any benefit.” Dr. Sigmon is a coffee drinker, and has no plans to stop.

この記事へのコメント

この記事へのトラックバック