A research group at Keio University and other institutions revealed that three characteristics, such as decreased usage frequencies of case particles and adverbs, exist in conversations of patients with schizophrenia. These findings have the possibility of becoming a foundation for indicators that objectively monitor language disturbances in schizophrenia, which sound incoherent and lack context. Rather than diagnosing symptoms through this method alone, researchers wish to use it as an opportunity leading to early diagnosis and treatment by combining it with other methods.
In diagnosis of psychiatric disorders, visible indicators like blood tests do not exist, and conversations in examination rooms serve as an important clue. A research group including Professor Taishiro Kishimoto, who specializes in behavioral science and psychiatry, at the Center for the Promotion of Interdisciplinary Research in Medicine and Life Science, Keio University School of Medicine conducted a comparative analysis of schizophrenia patients and healthy individuals. Specifically, the research group selected approximately 100 patients, from among over 500 patients who had been attending or hospitalized at cooperative hospitals and clinics of the university and agreed to have their conversations recorded, and compared their conversations with those of a nearly equal number of healthy individuals for analysis.
Recorded data comprised three types: "free conversation," "storytelling," and "picture description." As a result of detailed analyses, three characteristics were prominent in conversations of patients with schizophrenia: (1) frequency of using case particles bearing sentence structures decreases, (2) usage frequency of adverbs bearing modifier expressions decreases, and (3) meaning of used words is similar, lacking breadth.
Specifically, decreases in case particles such as "ga," "wo," and "to" make understanding sentence structures and semantic relationships difficult, decreases in adverbs representing degree or state such as "totemo" (very), "yukkuri" (slowly), and "tabun" (probably) make sentence meaning and context hard to understand, and similar words appear repeatedly in conversation. They explain that since these characteristics exist, conversations reportedly come across as confusing and lacking in context.
Kishimoto explained the significance, "Conversations of people with schizophrenia possess characteristics called loosening of association, such as being circuitous or jumping too far between topics. These results can serve as quantitative indicators even in psychiatric disorders."
It is important to note that the patients whose conversations could be analyzed in this study were not in an acute phase of illness, were willing and able to participate in conversations, and were in a condition that allowed informed consent to be obtained. Some individuals with schizophrenia experience severe auditory hallucinations or delusions that impair social functioning, while others may be unable to engage in calm conversation because of heightened anxiety or agitation. Conversely, similar conversational characteristics may also be observed in people with other psychiatric disorders, such as depression. The researchers therefore note that, for clinical applications, these findings would need to be used in combination with other assessment methods.
The research was advanced receiving grants from the Core Research for Evolutional Science and Technology (CREST) program of the Japan Science and Technology Agency (JST). The results were published in the British scientific journal Psychological Medicine on June 23. Keio University, Institute of Science Tokyo, and Shizuoka University announced the achievement on the same day.
Original article was provided by the Science Portal and has been translated by Science Japan.