A JOURNAL OF NEUROLOGY LETTER TO THE EDITOR Cognition and olfaction in Parkinson’s disease

Sir, We read with interest the recent paper in Brain by Bohnen et al. (2010), which suggested correlation between cognitive function and olfactory loss in Parkinson’s disease (Bohnen et al., 2010). They found that among 58 patients with Parkinson’s disease, those with poor episodic verbal memory had more impaired olfaction, as tested by the University of Pennsylvania Smell Identification Test (UPSIT). Additionally, there was border-line correlation between olfaction and non-verbal memory and Mini-Mental State Examination. We are conducting an ongoing study of non-motor manifestations of Parkinson’s disease, which includes a full neuropsychological examination and olfactory testing (Gagnon et al., 2009; Postuma et al., 2009). This allows us to quickly assess if these findings can be replicated. We have examined a group of 71 patients with idiopathic Parkinson’s disease. Mean age was 66.3 years and 50 (71%) were males. Disease duration was 5.0 3.4 years, Unifie