Imaging biomarker correlates with oxidative stress in Parkinson's disease.

BACKGROUND: While oxidative stress (OS) may be one of the crucial factors determining the initiation and progression of Parkinson's disease (PD), its correlation with gray matter (GM) atrophy is not known.

AIMS: To determine the GM volume (GMV) changes using voxel-based morphometry (VBM) and correlation with OS marker serum malondialdehyde (MDA) in PD.

MATERIALS AND METHODS: Seventy-two patients with PD were clinically evaluated and underwent magnetic resonance imaging (MRI) on a 3T MRI scanner using a 32-channel head coil. Lipid peroxidation product MDA levels were measured by spectrophotometry. MDA levels and regional GM differences using VBM were compared with 72 healthy controls.

RESULTS: The mean age of the patients was 51.3 ± 10.6 years and that of controls was 50.8 ± 10.4 years. The mean age of onset of symptoms in PD was 45.2 ± 11.3 years. In PD, serum MDA level was significantly higher than that in controls (0.592 ± 0.89 μmol/l vs. 0.427 ± 0.055 μmol/l; P < 0.0001). Compared to controls, patients had greater regional GM atrophy in all the brain lobes (P < 0.001, uncorrected). A significant positive correlation was found between GMV and MDA in the caudate nucleus (CN) and posterior cingulate gyrus (PC) in the patient group (P < 0.001, uncorrected).

CONCLUSIONS: We observed GM atrophy in all major brain lobes of patients when compared to controls. Only in the patient group, a significant positive correlation was observed in CN and PC with MDA. These findings suggest that, even though the whole brain is affected in PD, some of the non-substantia nigra regions of the brain, such as CN, may have some differential compensatory mechanism, which are preserved from oxidative damage.