Persistent loss of smell after COVID-19 may be linked to changes in brain regions involved in smell and emotion, even in mild cases. Illustration by the author.
Many people who caught COVID-19 experienced a loss of smell, but for some, this symptom never fully went away.
A new study published in Scientific Reports (2025) shows that this lingering smell loss might be linked to real changes in the brain -even in people who only had mild COVID-19. Researchers studied 61 people who had mild cases of COVID-19. Half of them still had problems with their sense of smell , while the others had recovered normally. None of the participants had been hospitalised. The team used special brain scans called
MRI diffusion imaging to look closely at brain regions involved in smell and emotion, including the amygdala, piriform cortex, and putamen . They found that people who continued to have smell problems showed measurable differences in these brain areas. The longer someone had lost their sense of smell, the more changes were seen, especially in the left amygdala and piriform cortex . These areas are known to process not just smell, but also emotions like fear and pleasure. The study also found that people with ongoing smell loss tended to report more anxiety and depression. The researchers think this may be because the parts of the brain that handle smell and emotion are closely connected . When smell is lost or distorted, it might affect how the brain regulates mood. Interestingly, the scientists believe these brain changes might not be from direct damage. Instead , the brain may be adapting or reorganising itself to adjust to the loss of smell. Still, these adaptations can influence emotional health and well-being. This research shows that long-term smell loss after COVID-19 isn’t just a problem with the nose, it also affects the brain and emotions. It helps explain why many people with long COVID report mood changes, fatigue, and emotional difficulties . The authors recommend that people with persistent smell loss get both neurological checkups and mental health support. Smell training, therapy, and ongoing monitoring could help the brain recover more fully over time.
Reference:
Thaploo, D., Schmill, L. P., Behrend, N., Gerlach, S., Fogel, C., Ruß, A.-K., Lieb, W., Schreiber, S., Maetzler, W., Maetzler, C., Krawczak, M., Weinert, N., Bahmer, T., Raquib, S., Fiedler, K., Vehreschild, J. J., Jansen, O., Mignot, C., Aludin, S., & Laudien, M. (2025). Alterations of the amygdala in post-COVID olfactory dysfunction. Scientific Reports, 15, Article 36104. https://doi.org/10.1038/s41598-025-23015-w