Where does anosmia collide?

Specific anosmia is a selective inability to detect a single odorant or odour class in a sense of smell that is otherwise normal, as some people cannot smell the “sweaty” steroid androstenone. Amoore’s 1967 and 1977 papers used such selective gaps as a probe into the olfactory code, hypothesising “primary odours” each tied to a receptor type. The referent is a selective perceptual gap and a research tool for mapping receptors, not a patient’s global loss of smell.[1][2]

Unit

A selective elevation of detection threshold for one odorant against normal overall smell

Recovery means

Not applicable

Measured by

Established by an odorant-specific detection threshold far above normal while thresholds for other odorants remain normal

In clinical medicine anosmia is the loss or absence of the sense of smell overall, whether from nasal obstruction, viral or traumatic damage, or neurodegeneration. Hummel and Welge-Lüssen’s Assessment of olfactory function describes how it is measured and graded as a sensory deficit. The referent is a global impairment of smelling, a symptom or diagnosis affecting a patient’s whole olfactory ability, not a selective gap for one molecule.[3]

Unit

The degree of loss of overall olfactory sensitivity

Recovery means

Some anosmia resolves as the cause clears (e.g., post-viral recovery); other cases are permanent; the label marks current loss, not necessarily permanence

Measured by

Quantified by standardised smell tests of threshold, discrimination and identification (e.g., Sniffin’ Sticks, UPSIT)