Effect of Herbal Perfumes and Synthetic Perfumes on Attention and Cognitive Functions in Young Adults: A Sequential Cross-sectional Study

Introduction: Focused and sustained attention, executive function, working memory and task switching are important cognitive abilities. Efforts to enhance cognitive abilities, have engaged the scientific community since ages. Human beings are exposed to several fragrances and the perception of the sense of smell, plays an important role in the physiological effects of mood, stress, and working capacity. Perception of olfactory stimuli involves complex brain processing, which can be directly associated with cognition and emotion. Several Electroencephalogram (EEG) studies have revealed that, fragrances significantly modulate the activities of different brain waves and are responsible for various states of the brain.

Aim: To objectively demonstrate the effect of olfactory stimulation with herbal (rose) perfume on attention and executive functions.

Materials and Methods: This sequential cross-sectional study was conducted in the Department of Physiology at Osmania Medical College, Hyderabad, Telangana, India. The duration of the study was one month, from 16th August 2021 to 16th September 2021. Study included 40 healthy participants (15 males and 25 females), aged between 18-30 years to olfactory stimulation by herbal (rose) extract perfume and synthetic (rose) perfume, and the effects are assessed, using the psychophysiological tests viz., Rapid Serial Visual Presentation task (RSVP), Trail Making Tests (TMT) A&B, Ruff Figural Fluency Test (RFT), and compared with the baseline scores, which are then analysed using Paired t-test. The data was analysed by using Statistical Package for Social Sciences (SPSS) version 16.0.

Results: Olfactory stimulation with herbal rose perfume enhances the attention and speed of processing, as shown by the nearly significant improvement in the performance of the TMT-A (p-value=0.05433), with decreased time taken to perform the test, whereas, the synthetic rose perfume enhanced the attention, speed, switching between tasks, cognitive fluency, and flexibility. This is evident by the significant improvement in the performance of the TMT-A (p-value=0.00326) and TMT-B (p-value=0.0001693), with decreased time taken to perform the tests. The derived index TMT (B-A), which removes the speed component and is a purer index of executive functions, also showed significant results (p-value=0.002092).

Conclusion: The effects of herbal and synthetic rose olfactory stimulation have shown positive influence on the attention and cognitive functions and this finding can be applied to create student friendly learning environments, by providing pleasant stimuli through means of aromatic sprays delivering the odorant in a pulsatile manner at a frequency to overcome the ensuing olfactory adaptation.