The First Thing to Go: Smell, Emotion, and the Invisible Onset of Parkinson’s

By Mindy Yang

Before the tremor, before the shuffle, before the slurred speech—there is often the absence of something so subtle, so easily dismissed, that it slips beneath our cultural radar: the loss of smell.

Parkinson’s disease is widely recognized for its motor symptoms, but the prodromal signs—those quiet harbingers of neurodegeneration—begin their work in shadows. Smell loss, or anosmia, is one of the earliest and most consistent indicators of Parkinson’s, often preceding diagnosis by up to a decade. According to research, up to 90% of people with Parkinson’s exhibit measurable olfactory dysfunction, years before the disease affects their movement.¹

The olfactory bulb, nestled at the base of the brain, is among the first regions affected by the accumulation of alpha-synuclein—the misfolded protein that characterizes Parkinson’s pathology. Its decline doesn’t just foretell what’s to come; it reorients one’s sensory world, subtly dismantling the emotional resonance of daily life.

Smell is a deeply emotional sense. It bypasses language and logic, reaching straight into the limbic system—the brain’s emotional and memory hub. A whiff of petrichor after rain, your lover’s shirt, the orange blossom of a childhood summer—these are not just aromas but time capsules, laced with intimacy and identity. The early erosion of this capacity is more than just a sensory glitch. It’s an existential one.

When you can no longer smell your morning coffee or the cedar floor of a bookstore, it’s not merely a matter of appetite or aesthetics. It’s your sense of belonging to the world that begins to fade.

This is the invisible heartbreak of Parkinson’s. And yet, in mainstream discourse and even clinical care, it’s often under-acknowledged. Emotions, too, are part of this vanishing act. Depression and anxiety are not just reactive states for people with PD—they are deeply biological components of the disease. These mood disorders often emerge early, even in the absence of motor symptoms, and may be exacerbated by the loss of sensory input that once grounded and oriented the self.

On April 17, the Michael J. Fox Foundation will host a special edition webinar titled “How Do You Feel with Parkinson’s?”, finally placing emotions—and, by extension, the senses—at the heart of the conversation. It’s a welcome rebalancing of the narrative. For far too long, Parkinson’s has been portrayed as a movement disorder. In truth, it is a feeling disorder, a being disorder, an unraveling of one’s intimate contract with the world.

There is a quiet revolution underway in the way we understand PD. New research is beginning to look at how interventions—ranging from mindful retraining of flavor perception to targeted neuromodulation of anxiety-related brain waves—may restore parts of what’s been lost.²³ Some labs are even investigating how olfactory training may slow progression in neurodegenerative disorders, much like physical therapy preserves motor strength. These aren’t just rehabilitative strategies—they’re acts of reclamation.

Caregivers, too, are entangled in this sensory-emotional matrix. When your loved one no longer reacts to the scent of your cooking, or when shared sensory rituals—wine, perfume, rain—lose their meaning, grief becomes ambient. This isn’t just a disease of neurons. It’s a disease of connection.

What we need now is a broader language of Parkinson’s. One that includes longing, scent, taste, and emotional resonance. One that acknowledges that loss often begins long before anyone notices a tremor. And perhaps, in attending more deeply to these early signs—these faint flickers in the dark—we can find new ways not only to diagnose earlier but to care more fully.

Sources:

1. Haehner et al., Olfactory loss as a predictor for Parkinson’s disease, Annals of Neurology (2007).

2. National Institutes of Health, Smell dysfunction and Parkinson’s: a biomarker of early disease.

3. The Guardian, Scientists use brain wave stimulation to ease anxiety in Parkinson’s patients (Feb 2025).