Investigations on the Functional connectivity disruptive patterns of progressive neurodegenerative disorders

Alzheimer's Disease (AD) and Parkinson's Disease (PD) are neurodegenerative diseases of the brain that affects the memory and motor regions respectively. Neurological disorders are the result of alterations at molecular level due to complex mechanisms between genetic and environmental factors. Classical approaches are focused on determining how disruptions in functional connectivity occur in the memory regions of AD and motor regions of PD. There have been studies stating that in addition to dementia, motor abnormalities may also be observed in Alzheimer's patients and on the other hand, dementia may occur in Parkinson's patients a year or more after the onset of motor symptoms. In this work, to substantiate this hypothesis the brain connectivity patterns and functional topology of motor and memory regions in AD and PD patients were analyzed and compared. Resting state functional connectivity (rs-fMRI) has been found to demonstrate the brain networks in both AD and PD. Graph theoretical modelling is being significantly used in studying the topology of the brain networks. The results show the disruption of connectivity in motor regions in later stages of AD in addition to memory regions and conversely in PD the memory regions were found to have disrupted connectivity in addition to the motor regions. Further, the Z scores of intra and inter hemispheric regions in AD and PD also indicate the disruption in connectivity as the disease progresses.