Olfactory Impairment Predicts Brain Atrophy in Parkinson's Disease: Figure 1.

Abstract

Olfactory dysfunction is a frequent nonmotor symptom in idiopathic Parkinson's disease (PD) and may be considered as an early clinical feature of the disease preceding motor symptoms by years. According to recent neuropathological staging concepts, impaired olfaction is assumed to indicate an early pathological process and might be associated with structural changes in the brain. A morphometric analysis of magnetic resonance images [voxel-based morphometry (VBM)] was used to investigate gray matter atrophy related to psychophysically measured scores of olfactory function in early PD patients (n ϭ 15, median Hoehn and Yahr stage 1.5), moderately advanced PD patients (n ϭ 12, median Hoehn and Yahr stage 2.5), and age-matched healthy controls (n ϭ 17). In PD patients, but not in controls, cortical atrophy in olfactory-related brain regions correlated specifically with olfactory dysfunction. Positive correlations between olfactory performance and gray matter volume were observed in the right piriform cortex in early PD patients and in the right amygdala in moderately advanced patients. The results provided first evidence that olfactory dysfunction in PD is related to atrophy in olfactory-eloquent regions of the limbic and paralimbic cortex. In addition, olfactory-correlated atrophy in these brain regions is consistent with the assumption that olfactory impairment as an early symptom of PD is likely to be associated with extranigral pathology.

Association of Olfactory Bulb Volume and Olfactory Sulcus Depth with Olfactory Function in Patients with Parkinson Disease

“…More recently, a morphometric analysis of MR imaging, called voxel-based morphometry, was used to investigate gray matter atrophy related to psychophysically measured scores of olfactory function in patients with early PD, patients with moderately advanced PD, and age-matched healthy controls. 13 The results provided first evidence that olfactory dysfunction in PD is related to atrophy in olfactoryeloquent regions of the limbic and paralimbic cortex. Recently, several studies have been set out to investigate the structural changes at the level of the OB and OS in patients with PD.…”

“…Although most patients with PD have olfactory deficits, 1,2,13,18,19,28 the pathologic mechanism is unknown. The present study indicated that there was atrophy of the olfactory system in the patients with PD, as shown by lower OB volume and OS depth compared with healthy controls.…”

“…To further diagnose the nature of the olfactory deficit, MR imaging can be used. 13,[15][16][17][18] A recent DWI study confirmed disruption of the olfactory tract in patients with early stages of PD, 34 and DWI would add an observer-independent and quantitative measure of symptoms in at-risk subjects. More recently, a morphometric analysis of MR imaging, called voxel-based morphometry, was used to investigate gray matter atrophy related to psychophysically measured scores of olfactory function in patients with early PD, patients with moderately advanced PD, and age-matched healthy controls.…”

“…12 A recent study demonstrated that olfactory dysfunction in PD is related to atrophy in olfactoryeloquent regions of the limbic and paralimbic cortices. 13 These olfactory deficits have been linked to structural and/or functional changes at the level of the OB 9,12,14,15 and OS. 16 There is evidence from numerous studies that MR imaging can be used to reliably evaluate the volume of the OB and the depth of OS.…”

The Predictive Role of Hyposmia in Alzheimer's Disease

“…Once IPD has become clinically manifest, olfaction appears to be already severely compromised, which is in line with the absence of longitudinal changes of olfactory function during IPD progression (Herting et al 2008). In a recent study (Wattendorf E et al, 2009) gray matter atrophy was investigated using morphometric analysis of magnetic resonance images voxel-based morphometry (VBM) and it was related to psychophysically measured scores of olfactory function in early PD patients, moderately advanced PD patients and age-matched healthy controls. Cortical atrophy in olfactory-related brain regions (mainly in the right piriform cortex in early PD patients and in the right amygdala in moderately advanced PD patients) was shown in PD patients, but not in controls, and it was specifically correlated with the olfactory dysfunction.…”