Olfactory identification in LRRK2 G2019S mutation carriers: a relevant marker?. (September 2014)

• Record Type: Journal Article
• Authors: Saunders‐Pullman, Rachel; Mirelman, Anat; Wang, Cuiling; Alcalay, Roy N.; San Luciano, Marta; Ortega, Robert; Raymond, Deborah; Mejia‐Santana, Helen; Ozelius, Laurie; Clark, Lorraine; Orr‐Utreger, Avi; Marder, Karen; Giladi, Nir; Bressman, Susan B.; the AJ LRRK2 Consortium
• Is Part Of: Annals of clinical and translational neurology. Volume 1:Number 9(2014)
• Page Start: 670
• Page End: 678
• Publication Date: 2014-09
• Subjects: Nervous system -- Diseases -- Periodicals; Neurology -- Periodicals; 616.8005
• DOI: 10.1002/acn3.95
• Languages: English
• ISSNs: 2328-9503

Abstract

<abstract abstract-type="main" id="acn395-abs-0001"> <title>Abstract</title> <sec id="acn395-sec-0001" sec-type="section"> <title>Objective</title> <p>Olfactory impairment is a potential marker for impending phenoconversion to Parkinson disease (PD) that may precede the development of disease by several years. Because of low specificity, it may be of greater predictive value in those with genetic mutations and its potential as a marker for developing <italic>LRRK2 </italic>PD should be evaluated.</p> </sec> <sec id="acn395-sec-0002" sec-type="section"> <title>Methods</title> <p>We examined olfactory identification in 126 <italic>LRRK2</italic> G2019S mutation carriers with PD, 125 mutation carriers not manifesting PD, 126 noncarriers with idiopathic PD, 106 noncarrier family members without PD, and 35 unrelated controls. We compared olfactory performance and performed mixture modeling to identify possible subgroups of olfactory performance in <italic>LRRK2 </italic>PD and nonmanifesting carriers.</p> </sec> <sec id="acn395-sec-0003" sec-type="section"> <title>Results</title> <p>Adjusting for sex, age, cognitive score, site, and smoking history, <italic>LRRK2 </italic>PD had better olfactory scores compared to idiopathic PD (mean olfaction difference: −3.7, <italic>P</italic> < 0.001), and both <italic>LRRK2 </italic>PD and idiopathic PD had worse olfaction than controls (−12.8, −9.1, both <italic>P</italic> < 0.001). <italic>LRRK2 </italic>PD were less likely to be hyposmic than idiopathic PD (54.8% vs. 80.2%, <italic>P</italic> < 0.001). Nonmanifesting carriers and noncarrier family members did not differ. Mixture model analysis identified three classes in the <italic>LRRK2 </italic>PD and nonmanifesting carriers, suggesting that there are subgroups with poor olfactory identification in both <italic>LRRK2 </italic>PD and nonmanifesting carriers.</p> </sec> <sec id="acn395-sec-0004" sec-type="section"> <title>Interpretation</title> <p>Therefore, olfactory identification deficit is less likely to be an obligate feature in <italic>LRRK2 </italic>PD than idiopathic PD, and while a relevant marker in some, a subset of carriers who eventually phenoconvert may proceed directly to PD without prior impaired olfaction.</p> </sec> </abstract>