Regional cerebral blood flow correlated with aphasia in dementia of the Alzheimer’s type and frontotemporal lobar degeneration

Individuals with neurocognitive disorders such as dementia of the Alzheimer's type (DAT) and frontotemporal lobar degeneration sometimes show characteristic language dysfunctions. As neurocognitive disorders progress, different types of aphasia may present. To evaluate the disease‑related changes of language functions, and to determine the correlation between the regional cerebral blood flow (rCBF) and language dyfunctions in patients with DAT or the behavioral variant of frontotemporal dementia (bvFTD) or semantic dementia (SD), we used a scale for speech and reading impairment in Japanese (the Standard Language Test for Aphasia [SLTA]), and perfusion single photon emission computed tomography, and we analyzed the relationships among them. Significant differences were identified among the DAT, SD, and bvFTD groups in the SLTA subscales concerning kanji (morphographic) words. There were positive correlations between the SLTA subscales concerning kanji words and the rCBF in left temporo‑occipital regions. The patients with bvFTD showed relative rCBF preservation in the posterior cerebrum compared with the DAT and SD patients. Our results indicate that aphasia for Japanese kanji words might be related to the dysfunction of temporo‑occipital regions, and they suggest that in patients with bvFTD, preserving the CBF in the posterior cerebrum might help maintain the ability to handle morphographic words such as kanji.