Background: The Kii peninsula of Japan, together with Guam and West New Guinea, has one of the highest incidences of amyotrophic lateral sclerosis (ALS) and parkinsonism-dementia complex (PDC) in the world.
Objective: To perform neuroimaging studies on patients with ALS and PDC on the Kii peninsula.
Methods: Results of computed tomography, magnetic resonance imaging, and single-photon emission computed tomography were studied in 4 patients with ALS and in 10 patients with PDC from the Hohara village on the Kii peninsula of Japan.
Results: In patients with PDC, there was mild to severe atrophy of the frontal and temporal lobes on computed tomography and magnetic resonance imaging and a marked decrease in cerebral blood flow on single-photon emission computed tomography. In contrast, in patients with ALS, there was a decrease in cerebral blood flow of the frontal and temporal lobes, although the patients did not show signs of clinical dementia or obvious brain atrophy on computed tomography or magnetic resonance imaging.
Conclusion: The finding of an obvious decrease in cerebral blood flow of the frontal and temporal lobes in patients with PDC and ALS with or without cerebral atrophy supports the concept that the 2 conditions are different manifestations of a single frontotemporal tauopathy.