Diagnosis of speech-altering dementia may be affected by one’s native language, finds a comparison of Italian- and English-speaking patients.

The study focused on adults diagnosed with primary progressive aphasia, a disease which affects language and is often associated with Alzheimer’s disease. Participants had similar cognitive function and physical brain degeneration. But differences surfaced when the researchers compared their performance on linguistic tests, wrote Maria Luisa Gorno-Tempini, M.D., Ph.D., from the University of California San Francisco.

English speakers had more trouble pronouncing words, a hallmark of PPA, and spoke less than usual. In contrast, Italian speakers had fewer pronunciation difficulties but produced much shorter and grammatically simpler sentences. In fact, the Italian speakers did not match the established diagnostic criteria for nonfluent PPA as closely as the English speakers, despite their other apparent similarities. 

The results may be due to the fact that the diagnostic criteria are based on studies of English-speaking patients, the researchers theorized.

“This means that there are probably many people, … including non-native English speakers in the U.S., who are not getting the right diagnosis because their symptoms don’t match what is described in clinical manuals,” said Gorno-Tempini. “This could lead to misdiagnosis if people are expressing symptoms differently due to their language or cultural background.”  

 The study was published Jan.10 in the journal Neurology.