Taste dysfunction in multiple sclerosis

Abstract

Empirical studies of taste function in multiple sclerosis (MS) are rare. Moreover, a detailed assessment of whether quantitative measures of taste function correlate with the punctate and patchy myelin-related lesions found throughout the CNS of MS patients has not been made. We administered a 96-trial test of sweet (sucrose), sour (citric acid), bitter (caffeine) and salty (NaCl) taste perception to the left and right anterior (CN VII) and posterior (CN IX) tongue regions of 73 MS patients and 73 matched controls. The number and volume of lesions were assessed using quantitative MRI in 52 brain regions of 63 of the MS patients. Taste identification scores were significantly lower in the MS patients for sucrose (p = 0.0002), citric acid (p = 0.0001), caffeine (p = 0.0372) and NaCl (p = 0.0004) and were present in both anterior and posterior tongue regions. The percent of MS patients with identification scores falling below the 5th percentile of controls was 15.07 % for caffeine, 21.9 % for citric acid, 24.66 % for sucrose, and 31.50 % for NaCl. Such scores were inversely correlated with lesion volumes in the temporal, medial frontal, and superior frontal lobes, and with the number of lesions in the left and right superior frontal lobes, right anterior cingulate gyrus, and left parietal operculum. Regardless of the subject group, women outperformed men on the taste measures. These findings indicate that a sizable number of MS patients exhibit taste deficits that are associated with MS-related lesions throughout the brain.

Keywords: Chemosensory transduction; Magnetic resonance imaging; Multiple sclerosis; Sex differences; Taste; Taste disorders.

Figure 1

Mean (± SEM) percent correct taste identifications for sweet (sucrose), salty (sodium chloride), sour (citric acid) and bitter (caffeine) tasting stimuli for the 146 subjects of the study (73 multiple sclerosis patients and 73 matched controls). The dependent measure reflects the percent of correct responses from a total of 24 trials for each stimulus (6 trials × 4 tongue regions). Copyright © 2015 Richard L Doty. See text for details.

Figure 2

Triplanar view of registration-based parcellation of the brain into superior, medial, and inferior frontal lobes, temporal lobes, cerebellum, thalamus, and brainstem. Other labels denoted in the text are not shown because several regions overlap. See text for details.

Figure 3

Left: Axial slice of the FLAIR image with semi-automatic lesion segmentation highlighted in red. Middle: Proton density weighted image. Right: T2-weighted image. See text for details.