When the Ability to Smell Goes Away
Why Read This
What Makes This Article Worth Your Time
Summary
What This Article Is About
Victoria Clayton explores the science and human cost of anosmia — the loss of the sense of smell — a condition affecting up to 22 percent of the global population that has long been dismissed by clinicians. Through patient stories, including Chrissi Kelly, who founded nonprofit groups after losing her smell following a viral illness, and a wine lover who later developed Parkinson’s disease, the article reveals how smell loss is far more than an inconvenience. Smell’s direct pathways to the brain’s amygdala and hippocampus make it uniquely tied to emotion, memory, and neurological health — and researchers have now linked smell disorders to 139 distinct medical conditions.
The article also traces the explosive growth of olfactory research spurred by Covid-19, which caused global smell loss at unprecedented scale. It explains the biology of the olfactory bulbs — the brain’s most vulnerable entry point for viruses and toxins — and introduces a promising, low-cost treatment called olfactory training, which harnesses neuroplasticity to help patients recover smell function. Scientists like Dr. Zara Patel at Stanford and psychologist Jonas Olofsson are at the frontier of this field, working to understand how smell connects to, and may help diagnose or even prevent, brain disease.
Key Points
Main Takeaways
Smell Loss Is Surprisingly Common
Up to 22 percent of the population lives with some form of smell impairment, yet the condition remains poorly understood, underdiagnosed, and minimized by clinicians.
Smell Bypasses the Brain’s Relay
Unlike all other senses, olfactory signals skip the thalamus and travel directly to the amygdala and hippocampus — the brain regions controlling emotion and memory.
A Window into Brain Disease
Smell loss can be an early warning sign of Parkinson’s, Alzheimer’s, and Lewy body dementia, as toxic proteins may first accumulate in the olfactory bulbs before spreading to other brain regions.
Covid Transformed Smell Research
With 60 percent of Covid patients experiencing smell loss, the pandemic triggered an unprecedented surge in olfactory science that has reshaped understanding of this long-neglected sense.
Olfactory Training Offers Hope
A simple, inexpensive therapy involving repeated smelling of familiar scents can improve function in about 30 percent of patients — and up to 50 percent when combined with a steroid sinus rinse.
The Olfactory Bulb: Brain’s Front Door
The olfactory bulbs are the most vulnerable part of the brain — a potential entry point for viruses, bacteria, toxins, and possibly even microplastics, making them medically significant beyond smell.
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Article Analysis
Breaking Down the Elements
Main Idea
Smell Is a Vital, Underappreciated Window into Brain Health
Clayton’s central argument is that the sense of smell — long dismissed as trivial — is deeply entangled with neurological health. Loss of smell can signal early-stage neurodegenerative disease, may directly worsen psychiatric conditions, and, via the olfactory bulbs, provides a uniquely vulnerable pathway into the brain. New research, accelerated by Covid, is overturning decades of scientific neglect.
Purpose
To Inform and Advocate for Greater Medical Attention to Smell
Clayton writes to educate a general readership about a neglected medical reality while implicitly advocating for clinicians to take smell disorders seriously. By weaving patient narratives with cutting-edge neuroscience, she makes the case that anosmia deserves the same diagnostic rigor and research investment as other sensory impairments that affect quality of life and brain health.
Structure
Narrative → Scientific → Clinical → Hopeful
The article opens with personal patient stories to hook the reader emotionally, then shifts into neuroscientific explanation of how smell works, followed by the clinical stakes (disease associations), and closes on a hopeful note with olfactory training research and Chrissi Kelly’s partial recovery. This four-stage progression anchors abstract science in lived human experience throughout.
Tone
Empathetic, Inquisitive & Scientifically Grounded
Clayton maintains a warm, patient-centered empathy throughout while keeping the science credible and precise. She avoids alarmism despite the serious disease links, letting researchers speak in their own words and balancing urgency with intellectual curiosity. The overall effect is accessible science journalism that treats both patients and scientists with equal seriousness.
Key Terms
Vocabulary from the Article
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Tough Words
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Relating to the earliest stage of a disease, before characteristic symptoms appear; the article uses it to describe the pre-symptomatic phase of Parkinson’s disease, during which smell loss may already be present.
“There are a lot of unknowns about the earliest — or prodromal — stages of Parkinson’s.”
A brain region that plays a key role in movement and reward; a defining feature of Parkinson’s disease is the major loss of dopamine-producing cells in this area, which may begin years before symptoms emerge.
“A defining feature of the disorder is a major loss of dopamine-producing cells in a brain region called the substantia nigra.”
A smell disorder in which a person detects phantom odors that have no external source — essentially smelling something that isn’t there, a hallucination of the olfactory system.
“Many others live with smell disorders like phantosmia, in which a person picks up phantom smells.”
The brain’s central relay station that filters and directs sensory signals to the cortex; notably, olfaction is the only major sense that bypasses the thalamus entirely, going directly to the limbic system.
“We now know that olfaction initially bypasses the thalamus — the brain’s central relay station.”
A partial reduction in the ability to smell, as distinct from anosmia (complete loss); one of the most common smell impairments, affecting a significant portion of the global population without full awareness.
“Researchers estimate that up to 22 percent of the population lives with smell impairments, like hyposmia (partial smell loss) or anosmia (complete smell loss).”
Airborne chemical molecules that bind to specialized olfactory receptor cells in the nasal cavity, triggering electrical impulses that are processed by the brain and perceived as specific smells.
“Millions of olfactory neurons in the upper nose detect these odorants, then send electrical impulses via the olfactory bulbs.”
Reading Comprehension
Test Your Understanding
5 questions covering different RC question types
1According to the article, olfactory signals reach the brain’s cortex by first passing through the thalamus, just like all other senses.
2According to the article, what do scientists suspect about the relationship between toxic proteins and Parkinson’s disease?
3Which sentence best explains why the olfactory bulbs are described as the “most vulnerable part of the brain”?
4Evaluate the following statements about olfactory training as described in the article. Mark each True or False.
In Dr. Patel’s randomized controlled trial, patients had to have experienced smell loss for more than a year to be eligible for inclusion.
A 2024 meta-analysis found that olfactory training had a statistically significant positive impact on smell function across the studies examined.
The traditional four scents used in olfactory training are lemon, rose, clove, and lavender.
Select True or False for all three statements, then click “Check Answers”
5The article notes that in the 19th century, Paul Broca called olfaction “the bestial sense,” which led to “decades of scientific neglect.” What can we most reasonably infer from this detail about the history of smell research?
FAQ
Frequently Asked Questions
The article explains that viruses can attack the olfactory support cells that surround and nourish olfactory nerve cells. When these support cells regenerate — typically within four to six weeks — smell often returns. However, in some cases the olfactory nerves themselves suffer lasting damage, and recovery is not guaranteed. A 2023 survey in the journal Laryngoscope found that 60 percent of Covid patients experienced smell loss, with most cases temporary but some persisting long-term.
Scientists suspect that the toxic proteins responsible for Parkinson’s — which ultimately destroy dopamine-producing cells in the substantia nigra — may first accumulate in the olfactory bulbs, years before motor symptoms like tremors or slowed gait appear. Because the olfactory bulbs sit at the base of the brain’s frontal lobes and are the most exposed region of the brain to the outside environment, they may be an early target for the pathological processes underlying the disease — making smell loss a prodromal, or pre-symptomatic, indicator.
Olfactory training works like physical therapy for the nose and brain. Patients practice smelling four familiar scents — traditionally lemon, rose, clove, and eucalyptus — twice daily, concentrating on recognizing each labeled scent and recalling the associated memory. The repetitive exposure is intended to generate new olfactory receptor cells and harness neuroplasticity — the brain’s ability to rewire itself. Dr. Zara Patel’s research suggests roughly 30 percent of patients see improvement, rising to 50 percent when paired with a steroid sinus rinse.
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This article is rated Intermediate. Written for a scientifically literate but non-specialist audience, it introduces technical medical terms — anosmia, hyposmia, parosmia, substantia nigra, neuroplasticity — that require careful reading but are generally explained in context. The structure moves fluidly between personal narrative and scientific exposition, demanding readers track both emotional stories and factual claims simultaneously. Those comfortable with health journalism will find it accessible; those newer to neuroscience may benefit from reading each section slowly.
Knowable Magazine is an independent, non-profit science journalism publication produced by Annual Reviews — one of the world’s most respected publishers of peer-reviewed academic review articles. Its mission is to make rigorous scientific knowledge accessible to a general audience. Articles draw directly on published research and interviews with active scientists, ensuring the journalism is grounded in the current state of academic understanding rather than speculation or press releases.
The Ultimate Reading Course covers 9 RC question types: Multiple Choice, True/False, Multi-Statement T/F, Text Highlight, Fill in the Blanks, Matching, Sequencing, Error Spotting, and Short Answer. This comprehensive coverage prepares you for any reading comprehension format you might encounter.
