Olfactory impairment in motor neuron disease: a pilot study.

The ability to identify smells was tested in nine males and six females with motor neuron disease (MND) of varying severity, using the University of Pennsylvania Smell Identification Test (UPSIT). The olfactory impairment found in MND patients compared with age and sex matched controls is statistically significant at the 0.005 level. The relationship with Parkinson's disease, with Alzheimer's dementia and the possible aetiological implications of this new aspect of the MND are discussed.