Concomitant pathologies among a spectrum of parkinsonian disorders

Introduction: Many clinicopathological studies do not specify the presence of other pathologies located within the brain, so disease heterogeneity may be under appreciated. Objective: The purpose of this study was to determine the frequencies of concomitant pathologies among parkinsonian disorders. Methods: Data from the Arizona Study of Aging and Neurodegenerative Disorders (AZSAND), an ongoing longitudinal clinical-neuropathological study, was used to analyze concomitant pathologies, including Alzheimer's disease (AD), argyrophilic grains (Arg), cerebral amyloid angiopathy (CAA), cerebral white matter rarefaction (CWMR) and overlap of each parkinsonian disorder in clinico-pathologically defined Parkinson's disease (PD; N=140), dementia with Lewy bodies (DLB; N=90), progressive supranuclear palsy (PSP; N=64), m. ultiple system atrophy (MSA; N=6), corticobasal degeneration (CBD; N=7); and normal elderly (controls; N=166). Results: Of the neuropathologically-confirmed PD cases, 38% had a concomitant diagnosis of AD, 9% PSP, 25% Arg, 44% CWMR, and 24% CAA. For DLB, 89% had AD, 1% PSP, 21% Arg, 51% CWMR, and 50% CAA. For PSP cases, 36% had AD, 20% PD, 1% DLB, 44% Arg, 52% CWMR and 25% CAA. Similar heterogeneity was seen for MSA and CBD cases. Many cases had more than one of the above additional diagnoses. Conclusions: These data demonstrate a great deal of concomitant pathologies among different types of parkinsonian disorders; this may help explain the heterogeneity of clinical findings.