The histopathological hallmark of Parkinson's disease (PD) and dementia with Lewy bodies (DLB) is the occurrence of insoluble fibrillary aggregates known as Lewy bodies. Mitochondria play a vital role in energy production, and the pathogenesis of PD is associated with altered cellular metabolism due to mitochondrial dysfunction. The pyruvate dehydrogenase (PDH) complex provides a primary step in aerobic glucose metabolism by catalyzing the oxidative decarboxylation of pyruvate to acetyl CoA. Pyruvate dehydrogenase alpha 1 (PDHA1) forms the core structure of the PDH complex. Dysfunction of the PDH complex leads to energy production failure, resulting in various neurological disorders. However, no study has investigated the involvement of PDHA1 in the pathogenesis of PD. In the present study, we performed immunohistochemistry and immunoblotting to clarify the involvement of PDHA1 in idiopathic PD, DLB, PARK14-linked parkinsonism (PARK14; a familial form of PD), and multiple system atrophy, in comparison with normal controls. Here we report PDHA1 as a new component of brainstem-type Lewy bodies in idiopathic PD, DLB and PARK14, the level of PDHA1 protein being significantly decreased in the putamen and substantia nigra of patients with idiopathic PD. Our findings suggest that alteration of glucose metabolism through dysfunction of the PDH complex might occur in the pathogenesis of Lewy body disease and PARK14.