Differences of Regional Cerebral Blood Flow between Early Alzheimer's Disease and Parkinson's Disease Associated with Dementia on 99mTc-Hexamethyl Propylene Amine Oxime Perfusion Single Photon Emission Computed Tomography

ABSTRACT

BACKGROUND: Alzheimer's disease (AD) and Parkinson's disease associated with dementia (PDD) are considered to be frequent types of cortical and subcortical dementia. Definitive diagnosis of neurodegenerative diseases is impossible without biopsy. Single photon emission computed tomography (SPECT) of the brain has long been used for years with cognitive disorders. Nevertheless, differential brain perfusion of patients with PDD and AD who exhibit mild dementia has not been reported. Therefore, we investigated the differences in the cerebral perfusional pattern using perfusion SPECT between mild AD and mild PDD to help clarify the diagnosis in the early stage of these dementias, since accurate diagnosis is crucial in decision regarding treatment, appropriate advice, management and prognosis. METHODS: Thirty-one patients with mild PDD and 32 patients with mild probable AD were enrolled in this study. All subjects underwent 99mTc-hexamethyl propylene amine oxime perfusion SPECT and general neuropsychological tests, and these data including perfusion images were analyzed. RESULTS: Perfusion SPECT showed hypoperfusion in frontal, parietal and temporal regions in both PDD and AD patients with mild dementia. Hypoperfusion in the occipital and cerebellar regions was significantly apparent in only PDD patients. CONCLUSION: Comparison of mild PDD with mild AD showed a significantly decreased perfusion in the occipital and cerebellar region in patients with mild PDD. Cerebral perfusion in the occipital region and the cerebellum could be a crucial differential diagnostic method of these diseases in the early phase. Further studies are needed for a definitive conclusion.