White matter integrity and cognition in Parkinson's disease: a cross-sectional study.
OBJECTIVE
We used diffusion tensor imaging (DTI) to test the following hypotheses: (1) there is decreased white matter (WM) integrity in non-demented Parkinson's disease (PD), (2) WM integrity is differentially reduced in PD and early Alzheimer's disease (AD) and (3) DTI changes in non-demented PD are specifically associated with cognitive performance.


METHODS
This study included 18 non-demented patients with PD, 18 patients with mild cognitive impairment due to incipient AD and 19 healthy elderly normal control (NC) participants in a cross-sectional design. The participants underwent DTI, and tract-based spatial statistics was used to analyse and extract radial diffusivity and fractional anisotropy. Correlations between scores from a battery of neuropsychological tests and DTI were performed in the PD group.


RESULTS
Patients with PD had significant differences in DTI in WM underlying the temporal, parietal and occipital cortex as compared with NC. There were no significant differences between the PD and AD groups in the primary region of interest analyses, but compared with NC there was a tendency for more anterior changes in AD in contrast to more posterior changes in PD. In a secondary whole-brain analysis there were frontoparietal areas with significant differences between AD and PD. In patients with PD, there were significant correlations between DTI parameters in WM underlying the prefrontal cortex and executive and visuospatial abilities.


CONCLUSIONS
In early, non-demented PD we found reduced WM integrity underlying the temporal, parietal and occipital cortices. In addition, WM integrity changes in prefrontal areas were associated with executive and visuospatial ability. These findings support that DTI may be an important biomarker in early PD, and that WM changes are related to cognitive impairment in PD.
Department of Geriatric Psychiatry, Akershus University Hospital, Lørenskog, Norway.
Eirik
E
Auning
Veslemøy Krohn
VK
Kjærvik
Per
P
Selnes
Dag
D
Aarsland
Astrid
A
Haram
Atle
A
Bjørnerud
Erik
E
Hessen
Abdolreza
A
Esnaashari
Tormod
T
Fladby
D000368:Aged; D000544:Alzheimer Disease / Q000209:etiology / Q000473:pathology; D003072:Cognition Disorders / Q000209:etiology / Q000473:pathology; D003430:Cross-Sectional Studies; D056324:Diffusion Tensor Imaging; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000150:complications / Q000473:pathology*; D066127:White Matter / Q000473:pathology*