Olfactory dysfunction in amyotrophic lateral sclerosis

Abstract

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 (P = 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.

Figure 1

Olfactory dysfunction in ALS and control participants. (A) UPSIT scores in ALS participants. (B) UPSIT scores in control participants. (C) 43.59% of ALS participants have olfactory dysfunction—33.33% had microsmia, and 10.26% total smell loss (anosmia). Conversely, 21.74% of controls had olfactory dysfunction—21.74% had microsmia, and none had anosmia. P = 0.003.