Effect of serotonin transporter genotype on self-reported efficacy and activity changes of brain prefrontal area in response to placebo.

Patients benefit from drug therapy not only through pharmacological mechanisms, but also through non-pharmacological action (placebo effect), which may be mediated in part by the prefrontal area of the brain. We consider that the difference between responders and non-responders to placebo might be related to polymorphisms in the serotonin transporter-linked polymorphic region (5-HTTLPR). To study this idea, we performed a randomized double-blind clinical trial using caffeine and lactose (placebo). Activity in the prefrontal area of the brain was measured in terms of blood flow by means of near-infrared spectroscopy (NIRS) as an objective indicator. Self-reported feelings of drowsiness on established scales were used as subjective indicators. Twenty-one subjects in block A took caffeine on the first day and placebo on the third day, and 21 in block B took placebo on the first day and placebo on the third day. After placebo administration, improvement of sleepiness was significantly enhanced, a similar extent to that after caffeine medication. Among the 42 subjects, 22 showed S/S type polymorphism in the serotonin transporter (52.4 %), 17 showed S/L type (40.5 %) and 3 showed L/L type (7.10 %). Statistical analysis of the results indicate that subjects with L/L genotype showed a significantly greater placebo response in terms of both self-reported feeling of drowsiness and blood flow in the prefrontal area of the brain associated with working memory (46 area). Our results indicate that the L/L genotype of 5-HTTLPR, which is rare in Japanese (3.2 %) but common in Americans (32.2 %), may be associated with a greater placebo effect.

[Senile type atopic dermatitis].

Twenty-five patients older than 50 years with atopic dermatitis (AD) diagnosed by the criteria of Tokyo Medical College were investigated on the basis of clinical course and features, IgE RIST, skin reactions, IgE RAST score to several antigens, and IgG4 levels in order to clarify the character of senile AD. The results were compared with the data from younger patients. It was found that the senile type AD showed various type of eczematous lesions whose onset was in the fourth decade of life, and higher IgE RIST and IgG4 levels than healthy people, but lower than younger AD patients. Immediate skin reactions to dermatophagoides and house dust were highly positive in the senile group like the younger group, while the reaction to spices was more highly positive (43%) than in younger persons. Clinically the recognition of the existence of senile type AD and the introduction of antiallergic therapy for severe eczema of old persons are important.