Some of the causes of olfaction problems are allergies, nasal polyps, viral infections and head trauma.
[3] Hyposmia is also an early and almost universal finding in Alzheimer's disease and dementia with Lewy bodies.
[6][7] The National Health and Nutrition Examination Survey (NHANES) collected data on chemosensory function (taste and smell) in a nationally-representative sample of US civilian, non-institutionalized persons in 2012.
In addition multiple demographic socioeconomic, and lifestyle characteristics were assessed as risk factors for diminished smell.
In statistical analyses, greater age and male sex, coupled with either black and/or non-Hispanic ethnicity, low family income, low educational attainment, high alcohol consumption (more than 4 drinks per day), and a history of asthma or cancer were independently associated with a greater prevalence of smell impairment.