Olfactory dysfunction in amyotrophic lateral sclerosis.

We utilized the well-validated University of Pennsylvania Smell Identification Test (UPSIT) to examine whether olfactory dysfunction occurs in ALS participants. After adjusting for relevant confounders in a multiple linear regression model, ALS participants scored significantly lower on the UPSIT compared with control participants, with an estimated mean difference of 2.31 points ( = 0.015). ALS participants also had twice the rate of olfactory dysfunction (microsmia or anosmia). This study suggests that olfactory dysfunction exists in ALS patients, which expands our understanding of the extramotor findings in ALS. Future investigations could determine whether there are correlations between olfactory dysfunction and specific ALS phenotypes.