Longitudinal study of primary progressive aphasia in a patient with pathologically diagnosed Alzheimer’s disease: a case report

Alzheimer’s disease is a neurodegenerative disease involving the deposition of pathologic amyloid-β and tau protein in the cerebral cortex. Alzheimer’s disease is commonly characterized by progressive impairment of recent memory. Primary progressive aphasia is also often observed in patients with Alzheimer’s disease. Moreover, language-associated symptoms, such as primary progressive aphasia, are diverse and varied in Alzheimer’s disease. However, nonfluent/agrammatic variant primary progressive aphasia is not generally considered a symptom of Alzheimer’s disease. To date, there has been no longitudinal study of primary progressive aphasia in Japanese-speaking patients or in patients speaking other languages with pathologically diagnosed Alzheimer’s disease. Here we present a longitudinal study of primary progressive aphasia in a Japanese patient pathologically diagnosed with Alzheimer’s disease.

A 75-year-old Japanese man, whose wife reported that his memory was impaired, also suffered from suspected aphasia. He was pathologically diagnosed with Alzheimer’s disease using ¹¹C-Pittsburgh compound-B positron emission tomography and ¹⁸F-THK5351 positron emission tomography. Based on clinical observation and the results of the Japanese standard language test of aphasia, he was also diagnosed with nonfluent/agrammatic variant primary progressive aphasia. During the subsequent 2 years, his cognitive impairment, aphasia, and behavioral and psychological symptoms of dementia progressed. Furthermore, progression of pathologic amyloid-β and tau protein deposition was revealed through ¹¹C-Pittsburgh compound-B positron emission tomography and ¹⁸F-THK5351 positron emission tomography. Although the results of [¹²³I] iodoamphetamine single-photon emission computed tomography suggested corticobasal degeneration, this was not observed on the [¹²³I] FP-CIT single-photon emission computed tomography (SPECT) (DaTscan). A previous study had reported that Alzheimer’s disease with a nonfluent/agrammatic variant primary progressive aphasia was accompanied by corticobasal degeneration; however, this was not true in our case.

This is possibly the first longitudinal study of nonfluent/agrammatic variant primary progressive aphasia in a Japanese-speaking patient with pathologically diagnosed Alzheimer’s disease, but without corticobasal degeneration.