Olfactory training: current status and request for the future

Olfactory training, proposed as a rehabilitation direction for nondrug recovery and treatment of olfaction, can be useful for various patients, including those with post-infection loss of sense of smell. Currently, significant variability exists in flavors used and duration and schemes of olfactory training. This analytical review is devoted to the methods of olfactory training to classify and systematize the techniques. The first successfully conducted and described study of olfactory training for the treatment of patients with loss of sense of smell of various etiologies was conducted for 12 weeks twice a day, where patients inhaled four fragrant substances isolated from essential oils (aromas: pink, eucalyptus, lemon, and clove). During rehabilitation, aromatic substances of various compositions were used — monocomponents, synthetic fragrances, essential oils, and household aromatic substances. The duration of olfactory training varied from 4 to 56–84 weeks. The training was most effective in the long-term exposure groups from 20 to 56 weeks. By selecting certain components and observing the training duration, this technique can improve the quality of the threshold sensitivity of aromas and their identification, which has a positive effect on health and many areas of human life and can be used in the rehabilitation of the sense of smell.