Abnormality of taste and smell in Parkinson's disease.
BACKGROUND
Smell sense is impaired in classic Parkinson's disease (PD). An initial study found no change in taste threshold in non-demented PD subjects and pathological studies suggest that the first relay for taste, the nucleus of the solitary tract, is spared. We wished to determine if taste is abnormal in PD and whether it is associated with smell dysfunction.


METHODS
Taste threshold was estimated using the Rion electrogustometer and olfaction by the University of Pennsylvania Smell Identification Test (UPSIT) in 75 non-demented PD patients and 74 controls.


RESULTS
There was a significant impairment of taste threshold and severe disorder of smell identification in the PD group. Age, duration of symptoms, disability, and smoking had no important effect on threshold measurement and there was no correlation between taste and smell dysfunction. Sensitivity analysis suggested that a provisional diagnosis of PD would be confirmed if smell or taste were abnormal; conversely, the diagnosis would merit review if both modalities were normal.


CONCLUSIONS
Impaired taste appreciation was found in about 27% of patients with clinically defined PD. There were no important effects from age, disease severity or smell sense. Given the sparing of the first and second order taste neurones in PD, disorder of taste in PD most likely signifies involvement of the frontal operculum or orbitofrontal cortex, in keeping with advanced disease, although confounding by drug effects and changes in salivary constitution could not be excluded completely.
Shah
Mussadiq
M
Smell and Taste Research Unit, Essex Neuroscience Centre, Queens Hospital, Romford, Essex, RM7 0AG, United Kingdom.
Deeb
Jacquie
J
Fernando
Marina
M
Noyce
Alastair
A
Visentin
Elisa
E
Findley
Leslie J
LJ
Hawkes
Christopher H
CH
D004192:Discrimination, Psychological; D004558:Electric Stimulation / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D000857:Olfaction Disorders / Q000453:epidemiology / Q000209:etiology*; D010300:Parkinson Disease / Q000150:complications* / Q000453:epidemiology; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D012684:Sensory Thresholds / Q000502:physiology; D012737:Sex Factors; D012903:Smell / Q000502:physiology*; D013649:Taste / Q000502:physiology*; D013651:Taste Disorders / Q000453:epidemiology / Q000209:etiology*; D014059:Tongue / Q000294:innervation / Q000503:physiopathology