MOVEMENT DISORDERS - ORIGINAL ARTICLE Odor recognition memory is not independently impaired in Parkinson’s disease Sanne Boesveldt Æ R. J. O. de Muinck Keizer Æ E. Ch. Wolters Æ H. W. Berendse Received: 14 August 2008 / Accepted: 17 March 2009 / Published online: 2 April 2009 Ó Springer-Verlag 2009 Abstract The results of previous studies in small groups of Parkinson’s disease (PD) patients are inconclusive with regard to the presence of an odor recognition memory impairment in PD. The aim of the present study was to investigate odor recognition memory in PD in a larger group of patients. Odor recognition memory and detection thresholds were assessed using components of the ‘‘Sniffin’ Sticks’’ test battery in 55 non-demented PD patients (Hoehn and Yahr stages I–III) and 50 control subjects of comparable age and sex. PD patients performed slightly but significantly worse than control subjects on the odor rec- ognition memory task. After correction for odor detection scores, however, the difference in odor recognition mem- ory performance between PD patients and controls was no longer statistically significant. These data indicate that odor recognition memory is not independently impaired in PD patients. Keywords Olfaction Á Parkinson’s disease Á Odor recognition memory Á Detection Introduction Olfactory deficits in Parkinson’s disease (PD) were first empirically documented in 1975 by Ansari and Johnson. Over the ensuing years, it has become clear that most PD patients have olfactory disturbances that are not restricted to a single functional measure but include impairments of odor detection, discrimination and identification (for review see Doty 1991). Clinical deficits in the sense of smell may even precede the development of overt motor symptoms (Haehner et al. 2007; Ponsen et al. 2004). Few studies have addressed odor recognition memory performance in PD patients. The results of these studies are inconclusive. A review paper based upon three small studies concluded that odor recognition memory is impaired in PD patients (Mesholam et al. 1998), whereas a separate study suggested that odor recognition memory may be intact in PD (Lehrner et al. 1997). Reduced olfactory acuity may, at least theoretically, affect performance on other olfactory tasks and thus lead to an underestimation of the actual performance on the olfactory task in question. It has been argued that olfactory detection thresholds should therefore always be assessed in addition to the specific olfactory measure under consider- ation and used in appropriate statistical analyses to correct for impairments in odor detection (Martzke et al. 1997). The aim of the present study was to investigate odor rec- ognition memory in a larger group of PD patients. Methods Subjects This study was performed in 55 control subjects and 63 PD patients. Eight subjects (four control subjects and four PD patients) had a score below 25 on the Mini Mental State Examination (Folstein et al. 1975) or a score below 27 on the CAMbridge COGnitive examination (Roth et al. 1986) S. Boesveldt Á R. J. O. de Muinck Keizer Á E. Ch. Wolters Á H. W. Berendse Department of Neurology, VU University Medical Center, Amsterdam, The Netherlands S. Boesveldt (&) Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, USA e-mail: sboesveldt@monell.org 123 J Neural Transm (2009) 116:575–578 DOI 10.1007/s00702-009-0208-y