Spatial characterization of brain activation in Parkinson's Disease research

Parkinson's disease (PD) affects 100,000 Canadians, and this number is expected to increase with the aging of the population. Primary symptoms include tremor, rigidity, slowness of movement, and posture instability. These motor disabilities are believed to be associated with the premature death of dopamine-secreting cells in the brain region Substantia Nigra pars compacta. However, the cause of this premature cell death is unknown, and symptoms often do not emerge until 80 per cent of the dopaminergic cells are lost. Detecting the onset of PD thus remains a major challenge, hindering the development of a cure. It is believed that substantial compensation occurs in the brains of PD patients, obscuring the early effects of disease. Therefore, current clinical assessments that rely on symptom severity may not provide an accurate measure of disease progression. Instead, it is predicted that abnormal brain activity changes will emerge long before substantial dopaminergic cells are lost. Thus, altered brain activity may serve as a more useful marker than symptom severity for diagnosing and treating PD. In order to disentangle compensatory mechanisms from disease effects, Bernard Ng is comparing the brain activity of PD patients at similar stages of disease progression, but with varying degrees of symptom severity. Specifically, he is using functional magnetic resonance imaging (fMRI),to study diseased-induced changes in brain activity within specific brain regions as well as changes in connectivity between brain regions. To more elaborately characterize brain activity, he is employing novel statistical spatial descriptors to examine the spatial distribution of regional activity in additional to the traditionally-employed intensity measures. By incorporating spatial information in this combined approach, better distinctions between compensatory mechanisms from disease effects would be enabled. Ng’s research aims to provide more accurate diagnosis of disease progression in PD patients, better assessment of medication effectiveness, and ultimately earlier PD detection.