Reduced sense of smell can have various causes, ranging in severity from 'worrying' to 'generally fatal'. Finding the true cause means ruling out or confirming each possibility – in other words, diagnosis.
Diagnosis is usually a complex process due to the sheer number of possible causes and related symptoms. In order to diagnose reduced sense of smell, we could:
|Parkinson's Disease||4%||Ruled out|
|Brain Tumor||1%||Ruled out|
|Cigarette Smoke Damage||0%||Ruled out|
|Cocaine Addiction||0%||Ruled out|
Has your sense of smell declined within the past few years, for reasons other than nasal congestion?
Possible responses:→ Don't know
→ No, my sense of smell has remained about the same
→ Yes, but it is due to ongoing nasal congestion
→ Yes, it is somewhat worse now
→ Yes, it is a lot worse now
Reduction of the sense of smell has been identified as an early sign of Alzheimer's disease since the 1970s.
Specifically, tumors of the frontal lobe.
Intranasal drug use can cause a loss of the sense of smell.
Toxins – especially acrylates, methacrylates and cadmium – can cause a reduction in the sense of smell.
[Kieff, D; Boey, H; Schaefer, P; Goodman, M; Joseph, M (1997). "Isolated neurosarcoidosis presenting as anosmia and visual changes". Otolaryngology – Head and Neck Surgery 117 (6): pp183-6]
[Rupp, Claudia I.; Fleischhacker, W. Wolfgang; Kemmler, Georg; Kremser, Christian; Bilder, Robert M.; Mechtcheriakov, Sergei; Szeszko, Philip R.; Walch, Thomas et al (2005). "Olfactory functions and volumetric measures of orbitofrontal and limbic regions in schizophrenia". Schizophrenia Research 74 (2-3): pp149-61]
Zinc deficiency is rare in the developed world, but it can cause impaired sense of smell or taste.