Assessing olfaction in the Italian population: methodology and clinical application

Disorders of the sense of smell are receiving growing clinical as well as experimental attention. Indeed, several neurological conditions have been associated with peripheral or central deficits of the olfactory system. In recent years, particular emphasis has been attributed to the early and severe olfactory impairment in neurodegenerative diseases, such as Alzheimer's dementia and Parkinson's disease. Olfactory assessment has also been included in comprehensive pre- and post-surgical evaluations of temporal lobe epilepsy. Moreover, the request for standardized methods of olfactory evaluation by forensic and occupational medicine is greatly increasing. Despite this requirement, there is no agreement in the Italian neurological community on olfactory assessment. This lack prompted us to generate a battery of standardized tests capable of bypassing cross-cultural differences in olfactory assessment and to be potentially useful in the clinical as well as experimental settings. Procedures of assessment of olfactory acuity (detection threshold), identification (multiple choice odor naming), discrimination (differentiation between similar/dissimilar odorants) and memory (recognition of a substance previously smelled) are fully described. In order to control bias factors depending upon the nature of the investigated disorder and the applied olfactory tasks, a minimal complementary neuropsychological assessment is recommended.