The vulnerable ventral tegmental area in Parkinson’s disease

•We ran a literature review on degeneration of the VTA in PD and added new cases.•The literature unequivocally demonstrates that the VTA is involved in PD.•Our new cases support previous ones with significant degeneration in the VTA.

IntroductionThe involvement of dopaminergic neurons in the ventral tegmental area (VTA) in Parkinson’s disease (PD) has not been universally recognized by neuroscientists and neurologists. Here, we conduct a review of previous research documenting dopaminergic neuronal loss in both the substantia nigra pars compacta (SNpc) and VTA and add three new post-mortem PD cases to the literature.MethodsPD and control brains were sectioned, stained for tyrosine hydroxylase, and cells in the SNpc and VTA were counted.ResultsBased on the review, we report two main results: (1) the VTA does degenerate in PD, and (2) the VTA degenerates less than the SNpc.ConclusionInconsistent clinical information about these cases limits our ability to interpret how the VTA contributes to PD symptoms. However, our data in combination with prior PD neuropathological cases in the literature unequivocally establish that the VTA is involved in PD, and could be relevant for future investigation of non-motor symptoms in PD.