Basophilic inclusions in the dentate gyrus (A–C; indicated by arrowheads) and variable cell loss in the CA1 subregion (D–F) in the three cases (A and D: case 1; B and E: case 2; and C and F: case 3) reported in this study. Immunostaining for PHF‐1 (G–I), 4R tau (J–L), 3R tau (M–P), p62 (Q–S) and for Gallyas silver staining (T–V) in cases 1 (G, J, M, N, Q and T), 2 (H, K, O, R and U) and 3 (I, L, Q, P, S and V) demonstrating the spherical inclusions in the dentate gyrus. Immunostaining for 3R tau in the CA1 subregion (N) demonstrates neurofibrillary tangles in case 1 corresponding to the immunoblot results. Note the argyrophilic astrocytes in (T)–(V) (arrows). The bar in (A) represents 25 μm for (A)–(C) and (G)–(V) and 100 μm for (D)–(F).