日本香粧品学会誌

Vol. 37, No. 3, pp.脳が決める効果
197–200（2013）： プラセボ効果の要因解析からわかること

197〈シンポジウム II〉『コスメサイコロジー（心理・生活者行動学）の真髄』

脳が決める効果： プラセボ効果の要因解析からわかること
井 澤 美 苗，信 野 明 美，西 村 友 宏，登 美 斉 俊，中 島 恵 美 *How the Brain Acts: Factor Analysis of Placebo Effects
Minae ISAWA, Akemi SHINNO, Tomohiro NISHIMURA, Masatoshi TOMI, Emi NAKASHIMA*
Abstract
Recent clinical research utilizing noninvasive functional measurement techniques has indicated that placebo effects
might be therapeutically useful, because clear responses to placebo administration have been observed in patients brains.
Both physiological and mental states are affected by placebo and a role of brain receptor（s）was suggested. Factors inﬂuencing the placebo effect are the Pavlov reaction, expectation, cognition, and conditioning. Further, the nocebo effect is a negative reaction caused by anxiety, which acts as a confounding factor. Different outcomes may be obtained depending upon
whether the placebo effect is evaluated in terms of objective or subjective responses. Correlation analyses of outcomes fromvarious clinical trials indicate that placebo improves subjective response more effectively than objective parameters. Psychosocial care of patients is an important aspect of welfare, and a better understanding of the mechanism of the placebo effectwill be helpful in this regard. Cognitive therapy is well known to be as efﬁcacious as antidepressant medication for treatingdepression. Therefore, we studied the relationship between activity in the cerebral prefrontal area and counselingintervention. Aromatherapy is known to be effective to improve mood. We thus evaluated the inﬂuence of counseling on theefﬁcacy of aromatherapy in healthy young women. Participants in a room ﬁlled with the fragrance of bergamot completed
both a self-reported questionnaire（motivation, feeling of drowsiness and general fatigue）and multi-dimensional fatigue
inventory-20（MFI-20）. Further, as an objective measure of changes in stress, blood ﬂow in the inferior frontal cortex wasevaluated by near-infrared spectroscopy（NIRS）. MFI-20 showed that the combination of aromatherapy with counselingsigniﬁcantly improved both brain activity and motivation, as compared to aromatherapy alone, though the self-reported questionnaire showed no signiﬁcant difference. Regional blood ﬂow in the inferior frontal cortex was signiﬁcantly decreased byexposure to aromatherapy with counseling, compared to aromatherapy alone（p＜0.05）. The value of the NIRS-derived
laterality index（LI）, which is considered to be a measure of stress, was decreased by aromatherapy with counseling. Thus,
we conﬁrmed that the combination of aromatherapy with counseling intervention signiﬁcantly improved mood and stress.
Our results also demonstrated that counseling intervention increased the effectiveness of aromatherapy.
Key words:

1.

placebo effect, nocebo effect, objective parameter, subjective response, counseling.

脳科学の進歩とプラセボ効果研究の現状ていると確認できるようになったことである 2）,3）。身体活動を高める心の要因としてプラセボ効果の要因解析研「病は気から」や「鰯の頭も信心から」の効果につい究が注目されている。プラセボに反応する脳内レセプて，科学的根拠はあるのだろうか。近年，脳と身体の関ターの存在や医学的症状とプラセボ効果に連動する生理係解明が進み，治癒力を高める心理効果の存在が明らか的および心理的条件がわかってきた。薬理効果と脳内レになってきた。心理効果の一つに偽薬（プラセボ）効果セプターを共有するプラセボ効果の存在も報告されていがある。これまで，多くのプラセボ効果は実態がなく，る 4）。

偽薬効果で，意味がないとされ，研究の対象外に置かれていた。プラセボ効果は長く新薬開発のノイズとして嫌2.

プラセボ効果の誘導要因と遮断薬

われてきた。しかし，今，治療におけるプラセボ効果のプラセボ効果はどんな場合に誘導されるのだろう。そ有効利用が論じられている 1）。プラセボ効果研究の最近して，それを治療に使うことはできるのだろうか。プラの特筆すべき進歩は，非侵襲的な手法で脳内の機能測定

セボ効果の誘導要因に，条件づけ，パブロフ反応，期待，が可能になり，実際に患者の脳内でプラセボ反応が起き認知，がある。期待感が起こすネガティブな反応として慶應義塾大学薬学部薬剤学講座〒105–8512 東京都港区芝公園 1–5–30
連絡先： E-mail: nakashima-em@pha.keio.ac.jp

Division of Pharmaceutics, Faculty of Pharmacy, Keio University（1–5–30 Shiba-koen, Minato-ku, Tokyo 105–8512, Japan）