The sense of smell is one of the oldest and most essential sensory modalities in terrestrial and aquatic organisms, playing a crucial role in survival, nutrition, and mating for non-human species. In humans and other mammals, the ability to distinguish thousands of different odors is attributed to specific odorant receptors that are continuously replaced every month through neuroneogenesis in the olfactory epithelium.
Historically, fragrances and perfumes held significant importance in ancient cultures such as Egypt, Greece, and China, where they were used for medical treatment, religious rituals, and personal grooming. The magic power of fragrances was believed to possess medicinal properties, and they were classified as either “pleasant” or “unpleasant.” In contemporary medicine, the loss of smell has been recognized as a potential diagnostic marker for neurodegenerative disorders like Alzheimer’s disease, Parkinson’s disease, and Multiple Sclerosis.
Research has shown that the regeneration of odorant receptors and inhibitory interneurons can provide a basis for long-term recovery from olfactory loss caused by respiratory infections or head trauma. Imaging disorders of olfaction have revealed clinically relevant structural changes in the brain network responsible for olfaction, which interact with other networks to facilitate higher cognitive functions such as memory, emotion, and social interaction.
However, these higher olfactory functions often remain undetected by patients and their doctors, highlighting the need for more intensive implementation of olfactory function and clinical testing in medical training. The study’s findings emphasize the importance of considering the impact of olfaction on human health and its potential as a diagnostic marker for various neurological disorders.
Source: https://www.frontiersin.org/journals/human-neuroscience/articles/10.3389/fnhum.2025.1588935/abstract