Effects of laserneedle acupuncture on olfactory sensitivity of healthy human subjects: a placebo-controlled, double-blinded, randomized trial

The aims of the present study were to investigate the influence of laserneedle acupuncture on olfactory sensitivity and to examine whether the attitude towards laserneedle acupuncture affects the outcome. Olfaction was tested repeatedly on two days using the olfactory detection threshold subtest of the Sniffin' Sticks test battery in sixty-four healthy subjects of which 32 showed a positive attitude towards the effects of laserneedle acupuncture and 32 were sceptic about its effects. Testing was accomplished three times on day one (T1 = 0 min, T2 = 35 min, T3 = 105 min) without laserneedle acupuncture and on day two (T1* = 0 min, T2* = 35 min, T3* = 105 min) when the subjects were randomized in a non-stimulation (placebo) and a stimulation (laserneedle acupuncture) group. Stimulation or non-stimulation was conducted in a double-blinded design. Following laserneedle acupuncture a significant decrease in olfactory detection thresholds was observed at both, T2* and T3*, whereas no significant changes were found in the baseline or placebo group. Effects of laserneedle acupuncture on the olfactory detection threshold did not differ between sceptic and non-sceptic subjects. In conclusion, laserneedle acupuncture is an effective method to improve olfactory sensitivity after one session of stimulation for at least one hour, independently of the attitude of subjects towards the stimulation method.