BERLIN ― Impaired language in bilingual individuals may be a novel indicator of schizophrenia, new research suggests.
A small study showed that participants diagnosed with schizophrenia who spoke two languages had more speech impairments in their second language (L2) than in their first language (L1), including using significantly more incomplete sentences and repeated words.
On the other hand, several verbal fluency markers were higher when conversing in the first language, signaling "a compensatory resource for communicative discourse in schizophrenia," investigators note.
"We found that symptoms of schizophrenia were mostly represented in the second language," lead author Daria Smirnova, MD, PhD, Department of Psychiatry at Samara State Medical University in Russia, told Medscape Medical News.
Dr Smirnova noted that because the participants were fluent in both languages, these findings were not due to "incompetence of second language." Rather, it could be because of the way the brain of those with schizophrenia processes speech.
She added that if these results are replicated in larger populations, it might be worthwhile to add speech therapy to cognitive therapy interventions for these patients.
"We could include language remediation to cognitive remediation techniques so that we could teach our patients, basically, the language of health. Language-oriented techniques could possibly influence the neural zones in the left hemisphere of the brain."
The study was presented here at the 27th European College of Neuropsychopharmacology (ECNP) Congress.
Crucial Role in Research
The investigators note that previous research has shown that immigration can affect symptoms of schizophrenia, and even increase the prevalence of psychosis in this population.
However, although bilingualism from immigration has led to increased research in the areas of sociology and linguistics, few studies have examined the interaction of bilingualism and schizophrenia ― even though language has been shown to play a role in the pathogenesis of the disorder.
"Past studies have suggested that first language is based in both the right and left hemispheres. Language processing is mostly based in zones in the left hemisphere," said Dr Smirnova.
"Semantics and understanding deep levels of language is in the right hemisphere. But the left hemisphere is mostly used to process a second language and language issues. And the left hemisphere is mostly what is affected by schizophrenia," she explained.
By comparing the two languages spoken by bilingual patients, "we hope to shed new light on the linguistic profile of the disorder, thus focusing on the crucial role of language in schizophrenic research," write the researchers.
A total of 60 Russian immigrants in Israel with schizophrenia were initially enrolled and screened. Of these, 10 (80% men; mean age, 33.8 years) who spoke both Russian and Hebrew fluently met study criteria.
The mean length of residence in their new country was 14.6 years, time of immigration to diagnosis was 5.3 years, and Positive and Negative Syndrome Scale (PANSS) total score was 94.9.
All participants underwent separate interviews conducted in both of their languages, and the researchers examined the transcriptions for "clinical, linguistic, and fluency markers of speech."
Results showed that three linguistic markers occurred significantly more often in the second language than in the first. These included incomplete syntax (11.82 vs 5.78 occurrences per 1000 words, P = .013) and lexical repetition (26.6 vs 16.06 occurrences, P = .034).
Exophoric reference, or using a pronoun or word to refer to something/someone not named before, was also significantly higher (P = .028).
"The higher frequency of linguistic markers of schizophrenia in L2 show more impairments in the syntax/semantic components of language use, where different neural representations may underlay the two languages in a bilingual brain damaged by schizophrenia," write the researchers.
A fourth language marker, "unclear reference" (such as using pronouns incorrectly), also trended higher in L2 but was not statistically significant.
Useful for Diagnosis?
When examining fluency markers, discourse markers (using linking words such as "actually" or "so" or "anyway" to continue the conversation) were significantly higher in L1 than in L2 (10.01 vs 2.31 occurrences, P = .020). Codeswitching (using elements of both languages in a single conversation) was also higher when the patients were interviewed in their first language, but not significantly so (5.80 vs 3.94).
"The higher frequency of fluency markers in L1 reflects motivation to maintain verbal fluency, evidenced in particular by the use of L2 lexical items, which afford a compensatory resource for communicative discourse in schizophrenia," explain the investigators.
There were no significant differences between L1 and L2 for the two clinical speech markers of blocking and topic shifting.
If future studies reflect the same type of findings, Dr Smirnova noted that it could possibly be helpful to train patients to construct and complete sentences more correctly in the second language, so that they would use brain zones in the left hemisphere more.
She added that there are currently no good treatments for negative symptoms in schizophrenia. "So language remediation within cognitive therapy could be a powerful future treatment development."
Dr Smirnova reported that the investigators are planning an upcoming study that would examine Russian patients with schizophrenia who immigrated to Australia and who speak both Russian and English fluently. They then hope to assess Russian patients who have moved to Germany, followed by more studies in other countries.
"It will be very interesting to expand this to international research and compare languages, especially those that have been shown to use the right hemisphere more," she said.
"Also, perhaps including language criteria into diagnostic criteria for schizophrenia could be important."
"This is really interesting. The paper shows the functional deficits that are more pronounced in the second language of these Russian immigrants to Israel," Paul Cumming, PhD, visiting scientist at the University of Oslo, Norway, told Medscape Medical News.
"And that seems to have implications for the disturbances in schizophrenia," added Dr Cumming, who was not involved with this study.
He noted that this appears to be a nice first step with which to build future research. He also said it reminded him of a study done "years ago" about functional activation of the brain in L2 involving a larger network than simply the basal ganglia.
"The sensation is that second language is more effortful because it engages more of the brain than does one's first language, which comes naturally," said Dr Cumming.
"So I think this study has broad implications about the nature of language acquisition and brain network dysfunction in schizophrenia."
The study authors and Dr Cumming have reported no relevant financial relationships.
27th European College of Neuropsychopharmacology (ECNP) Congress. Abstract P.3.b.017. Presented October 20, 2014.
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Cite this: Impaired Language May Indicate Schizophrenia - Medscape - Oct 27, 2014.