SynopsisThe importance of odorants in human life has long been recognized. Literature contains different approaches of physiological and psychological effects of odorant compounds, fragrances and essential oils. This work discusses odorants inhalation effect, based on an overview of major studies in humans. Beneficial effect of fragrances is mainly related to human behaviour. Studies document odorants influence in sympathetic and parasympathetic nervous systems, and neurophysiological brain activity. Moreover, odours compounds can act on the neuroendocrine system, neurotransmitters and neuromodulators, influencing psychological behaviour as well as body function. Odorant inhalation modulates physiological pathways, and in some cases, results in skin function regulation. The mechanism is incompletely elucidated. These findings suggest that olfactory system plays a role in central nervous system function beyond that of smell. In this overview, it was observed that odour compounds influenced stress biomarkers, dehydroepiandrosterone, oxidative stress, estradiol, dopamine, cutaneous barrier, sebum secretion and cutaneous immune system in humans. Some can be related with skin function. As the skin is associated with an extensive biochemical cascade and has complex mechanisms, studies have far to go, as there are processes not yet investigated related to skin that may be affected through olfaction. Future researches are needed to further understand and describe the mechanisms of action of physiological effects in fragrance compounds.R esum e L'importance des substances odorantes dans la vie humaine est reconnue depuis longtemps. La litt erature contient des approches diverses des effets physiologiques et psychologiques des compos es odorants, des parfums et des huiles essentielles. Ce travail aborde les effets des odorants par inhalation, il est bas e sur une vue d'ensemble des principales etudes chez l'homme. L'effet b en efique des parfums est principalement li e au comportement humain. Les etudes documentent que les odorants influencent les syst emes nerveux sympathique et parasympathique, et l'activit e neurophysiologique du cerveau. En outre, les compos es de mauvaises odeurs peuvent agir sur le syst eme neuroendocrinien, les neurotransmetteurs et neuromodulateurs, influencer le comportement psychologique ainsi que la fonction du corps. L'inhalation odorante module les voies physiologiques, et dans certains cas, peut entraîner la r egulation de la fonction de la peau. Le m ecanisme n'est pas compl etement elucid e. Ces r esultats sugg erent que le syst eme olfactif joue un rôle dans le fonctionnement du syst eme nerveux central au-del a de l'odorat. Dans cet aperc ßu, il a et e observ e que les compos es odorants influencent les biomarqueurs du stress, le d ehydro epiandrost erone, le stress oxydatif, l'estradiol, la dopamine, la barri ere cutan ee, la s ecr etion de s ebum et le syst eme immunitaire cutan e chez l'homme. Certains peuventêtre li es a la fonction de la peau. Comme la peau est associ ee a une large...

Implications for opportunities to prevent ACD by utilizing less-allergenic alternatives appear robust; however, we do not wish to over generalize interpretations because of important limitations.

The special interest group on sensitive skin of the International Forum for the Study of Itch previously defined sensitive skin as a syndrome defined by the occurrence of unpleasant sensations (stinging, burning, pain, pruritus and tingling sensations) in response to stimuli that normally should not provoke such sensations. This additional paper focuses on the pathophysiology and the management of sensitive skin. Sensitive skin is not an immunological disorder but is related to alterations of the skin nervous system. Skin barrier abnormalities are frequently associated, but there is no cause and direct relationship. Further studies are needed to better understand the pathophysiology of sensitive skinas well as the inducing factors. Avoidance of possible triggering factors and the use of well-tolerated cosmetics, especially those containing inhibitors of unpleasant sensations, might be suggested for patients with sensitive skin. The role of psychosocial factors, such as stress or negative expectations, might be relevant for subgroups of patients. To date, there is no clinical trial supporting the use of topical or systemic drugs in sensitive skin. The published data are not sufficient to reach a consensus on sensitive skin management. In general, patients with sensitive skin require a personalized approach, taking into account various biomedical, neural and psychosocial factors affecting sensitive skin. Emotion1.77 1. 44-2.17 Comparison between people with sensitive skin and healthy subjects. Results from a meta-analysis.

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There is a need to better define how the efficacy of investigational drugs is affected by study design, implementation, and placebo responses in randomized controlled trials. The improvements observed in placebo groups within trials examining psoriasis treatments may be partially due to study design and implementation. We conducted a systematic review of randomized placebo-controlled trials assessing the efficacy of biologics in the treatment of psoriasis and psoriatic arthritis to evaluate rates of placebo and active drug responders to determine specific factors within study design that may contribute to placebo responses. We included randomized, placebo-controlled trials of etanercept, infliximab, adalimumab, golimumab, ustekinumab, alefacept, and efalizumab that utilized Psoriasis Area Severity Index as an outcomes measure. We compared the rates of the placebo treatment arm versus the active drug arm achieving 75 % improvement of Psoriasis Area Severity Index. 31 trials involving 8285 active treatment and 3999 placebo patients were included. Rates of placebo responders (4.14 %) were significantly lower than active drug responders (48.4 %). The overall odds ratio calculated was 23.94 (p < 0.0001, 95 % CI 16.02-35.76). Binomial regression models showed that treatment indication, randomization fraction, a PASI inclusion requirement, and the time period of outcomes measure documentation affect placebo responses. Placebo responses seen in randomized controlled trials evaluating biologics in the treatment of psoriasis are not likely due to a physiologic mechanism, but may be secondary to chronic disease course and factors of clinical trial design and implementation.