Olfaction and apathy in Parkinson's disease.

Background: Olfactory deficits are frequent among patients with idiopathic Parkinson's disease (PD). Additionally, apathy (as quantified by the Apathy Evaluation Scale), is more prevalent in PD patients compared to the general population. Olfactory impairment and apathy are associated with dysfunction in overlapping brain regions. Neuroimaging studies indicate that the anterior cingulate gyrus and medial orbitofrontal cortex are hypoactive in apathetic patients and are also involved in secondary olfactory processing. However, no study until this point has been published investigating whether there is any association between olfactory dysfunction and apathy in PD patients.

Methods: In our study seventy consecutive patients with PD took the Brief Smell Identification Test (B-SIT), completed the Apathy Evaluation Scale (AES) and were administered the Folstein Mini-Mental Status exam (MMSE).

Results: Apathetic PD patients performed poorly on the B-SIT compared with non-apathetic PD patients and olfactory impairment correlated with apathy. The simultaneous disruption of olfaction and emotion in Parkinson's could be the result of disease pathology in brain regions involved in both olfactory and emotional processing and reinforces the idea that this link between olfaction and emotions may have clinical consequences.