DEAR DOCTOR: Some years ago, I was addicted to cocaine. I've overcome that addiction, but it has cost me my sense of smell. Why did this happen, and what can I do?
DEAR READER: It's difficult to overstate the many ways we rely on our sense of smell. Not only does it provide a crucial connection to the physical world around us, but it's a direct link to the events and feelings of our past. Whether it's the scent of a wildfire on the way, the whiff of food going bad in the fridge, or the trace of perfume that instantly calls up memories of a bygone time and place, the sense of smell plays an important role in our safety and quality of life. It's intricately tied to our sense of taste as well, as anyone who has tried to enjoy a favorite food with a stuffed nose knows all too well.
Our sense of smell, also referred to as olfaction, arises from the millions of specialized nerve cells, called olfactory sensory neurons, that are found in a small area of tissue located high up in the nasal cavity. Each time we breathe in, we inhale the millions of microscopic molecules that are being released by the environment around us. They rush up into the nose and stimulate the odor receptors found on those specialized nerve cells, each of which connects directly to the brain. The brain then interprets the chemical signals it receives as scent.
A diminished sense of smell, known as hyposmia, or a complete loss, known as anosmia, is often due to a blockage in the nasal sinuses, which prevents the scent molecules from reaching the olfactory neurons. This can be the result of inflammation, infection or injury.
Our sense of smell is also affected when the sensory neurons themselves get damaged. Although olfactory sensory neurons are continually replaced throughout a person's lifetime, it's possible for the damage or injury to be profound enough that the cycle of repair may be incomplete or even impossible. More rarely, smell disorders may involve injury, disease or dysfunction in the scent pathways within the brain.
Unfortunately, snorting cocaine can damage the inside of the nose in a variety of ways, including chronic constriction of blood vessels, atrophy of the delicate mucous membranes, damage to the flesh and cartilage, and permanent injury to the olfactory nerves themselves. We understand why you connect your diminished ability to smell with your previous cocaine use.
However, a number of other factors may be at play, which is why we think self-diagnosis is risky. Chronic sinus disease, a cold or the flu, injury to the nose or head, smoking, seasonal allergies and dental problems can often result in a diminished sense of smell. Aging plays a role as well, with one-fourth of people older than 50 experiencing hyposmia or anosmia. A diminished or lost sense of smell can be a symptom of conditions such as Alzheimer's disease, Parkinson's disease, polyps or tumors. With so many potential causes for the change to your sense of smell, we think it's important to seek out a diagnosis from an experienced specialist.
Eve Glazier, M.D., MBA, is an internist and associate professor of medicine at UCLA Health. Elizabeth Ko, M.D., is an internist and assistant professor of medicine at UCLA Health.