The higher the number of brain lesions detected by MRI in patients with multiple sclerosis (MS), the higher the likelihood of taste deficits, according to a study published in the Journal of Neurology.
Researchers from the U.S. and Turkey sought to determine if there was a quantitative measure of taste function that correlated with the punctate and patchy myelin-related lesions found throughout the central nervous system of patients who have MS.
Seventy-three patients with MS and 73 matched control subjects participated in this study. They were given 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. “The number and volume of lesions were assessed using quantitative MRI in 52 brain regions of 63 of the MS patients,” the authors wrote.
The results showed that taste identification scores were significantly lower among patients with MS than controls for all four tastes, and were present in both anterior and posterior tongue regions. Nearly twice as many of the patients with MS had taste scores below the fifth percentile as had been demonstrated in earlier studies:
“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,” the authors wrote.
Women outperformed men on the taste measures, they added.
"This study represents the most comprehensive study preformed to date on the influences of MS on the ability to taste," lead author Richard Doty, PhD, said in a release. "It appears that a sizable number of these patients exhibit taste deficits, more so than originally thought. This suggests that altered taste function, though less noticeable than changes in vision, is a relatively common feature in MS.
"These findings give us a better insight about that relationship, as well as the areas of the brain that are more likely to impact the dysfunction when scarred from the disease."
Reference: Doty RL, et al. Taste dysfunction in multiple sclerosis. J Neurol. 2016 Jan 25. [Epub ahead of print]