History of smoking and olfaction in Parkinson's disease.
OBJECTIVE
Olfactory dysfunction is the most common pre-motor symptom in Parkinson's disease (PD), and smoking is known to be associated with lower risk of PD. This study tested the hypothesis that smoking is associated with better olfaction in PD.


METHODS
Smoking history was obtained from 76 PD subjects (22 with a history of smoking [smokers], 54 who never smoked [nonsmokers]), and 70 controls (17 smokers, 53 nonsmokers). Olfaction was assessed using the 40-item University of Pennsylvania Smell Identification Test (UPSIT). The olfactory scores between groups and subgroups were compared using analysis of covariance with adjustment for age, gender, and monoamine oxidase B (MAO-B) inhibitor usage.


RESULTS
Overall the olfactory score was lower in PD compared with controls (olfactory scores: 21.5 vs. 33.5, P < 0.0001). Among controls, there was no significant difference in olfaction between smokers and nonsmokers (olfactory scores, 33.2 vs. 34.2; P = 0.95). Among PD subjects, however, smokers scored significantly better regarding olfaction compared with nonsmokers (olfactory scores: 24.4 vs. 19.9, P = 0.02).


CONCLUSIONS
These data suggest that a history of smoking is associated with better olfaction among PD patients. The finding may be related to why smoking may be protective against PD. Further studies are needed to confirm this finding and investigate the underlying mechanisms.
Department of Neurology, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, PA, USA.
Elisabeth B
EB
Lucassen
Nicholas W
NW
Sterling
Eun-Young
EY
Lee
Honglei
H
Chen
Mechelle M
MM
Lewis
Lan
L
Kong
Xuemei
X
Huang
D000368:Aged; D000978:Antiparkinson Agents / Q000627:therapeutic use; D005260:Female; D006801:Humans; D007980:Levodopa / Q000627:therapeutic use; D008297:Male; D008609:Mental Status Schedule; D008875:Middle Aged; D008996:Monoamine Oxidase Inhibitors / Q000627:therapeutic use; D000857:Olfaction Disorders / Q000175:diagnosis* / Q000188:drug therapy / Q000209:etiology*; D010300:Parkinson Disease / Q000150:complications* / Q000188:drug therapy; D012903:Smell / Q000502:physiology; D012907:Smoking / Q000503:physiopathology*
D000978:Antiparkinson Agents; D008996:Monoamine Oxidase Inhibitors; D007980:Levodopa
Parkinson's disease; cigarette; olfactory; smoking