Role of Mesocorticolimbic Pathway in Apathy of Patients With Parkinson's Disease. - Study Using Diffusion Tensor Imaging and Fibres Tracking

Use lay language. Apathy is one of the most under recognised, underdiagnosed and poorly managed aspects of Parkinson's disease. Depending on methodological approach of the study, its prevalence is estimated to be between 16 and 51%. Apathy derives from a dysfunction of the dopaminergic meso cortico limbic systems, which seems to play a central role in the control of mood and motivation. The subcortical components of this system are the ventral tegmental area (VTA), the nucleus accumbens, and the constituents of the limbic system (particularly the hippocampus and amygdala), all of which are located deep inside the brain (18). The hypothesis is that depletion of striatal dopamine from regulators located in the midbrain (VTA and SNpc) in striato-thalamo-cortical circuits results in hypofunction of these circuits and the loss of frontal cortical activity, particularly within in the frontal orbital cortex, the anterior cingulate cortex and the prefrontal cortex The objective of this study is to explore, using diffusion weighted MRI, the regions of the brain which are proposed to play a role in motivation in apathetic Parkinson's disease patients and to define more precisely the relation between dopaminergic fibres and the meso-cortico-limbic system with the help of tractography methods