Most people don’t think twice about the familiar scent of their favorite soap or shower gel. But what if one day that scent suddenly seems faint—or disappears completely? Health researchers say small changes like this may sometimes be worth paying attention to. According to Professor Davangere Devanand, a psychiatrist and neurologist at Columbia University, difficulty recognizing familiar smells could occasionally be one of the early signals linked to cognitive decline. Because the sense of smell is closely connected to areas of the brain responsible for memory, subtle changes in how scents are perceived may appear before other noticeable symptoms.
Scientists have long studied the connection between smell and brain function. The olfactory system—the part of the brain that processes smells—is directly linked to regions such as the hippocampus and amygdala, which are involved in memory and emotions. These areas are also among the first to be affected in conditions like Alzheimer’s disease. When the brain begins to struggle with processing scents, a person may notice that familiar smells such as soap, coffee, or perfume become harder to identify.
Researchers say that this change doesn’t only happen in the shower. Some people may notice that food aromas seem weaker than before, that flowers or perfumes are harder to distinguish, or that different scents begin to smell similar. While these experiences can sometimes be related to normal aging, temporary illnesses, allergies, or sinus issues, experts say persistent changes in the sense of smell without a clear cause may be worth discussing with a healthcare professional.
Several studies have explored this connection further. Research from Columbia University found that older adults who had difficulty identifying common scents were more likely to experience cognitive decline in the years that followed. Because of this, smell identification tests are being studied as a simple and non-invasive way to help detect early neurological changes. Experts emphasize that noticing a change in smell does not automatically indicate a serious condition, but staying aware of subtle changes in the body can play an important role in maintaining long-term brain health.