August 30, 2005

Schizophrenia Link to Hand Usage in Japan

Ambiguous or mixed hand use is related to having schizophrenia symptoms in Japanese people. Often those who are naturally left-handed adopt right-handedness because of cultural pressures. This only confirms research that "atypical cerebral lateralization" which has to do with being left-handed or ambidextrous, is a risk factor for schizophrenia.

413 Japanese individuals who were healthy took the Annett handedness questionnaire as well as a schizotypy scale (STA). At first the results were confusing due to the fact that there was originally no link between hand use and one's STA scores. But then it was noted that very few of the Japanese students had been "full left-handers". Only 1% had noted that they were so.

Researchers then re-evaluated their results by noting the cultural differences that might have effected their scores. They thought the scores might be due to some of the individuals being encouraged to switch from left-handedness to right-handedness at a young age. When asking the participants if this had been done to them, 51 reported that this was what had happened to them.

When this was noted in the data, it was found that they had higher STA scores than those who had not been forced to switch. Also it was found that "males who were non-right handers, and who presumably had mixed-handedness, having significantly higher STA scores than full right-handers" (PsychiatryMatters.MD).

These results support the claim that left-handedness and being ambidextrous was a risk factor for schizophrenia symtoms.

Original Source: Schizotypy and handedness link found in Japanese population. PsychiatryMatter.MD. 2005.

This research article was published in Schizophr Res 2003; 65: 139-145.


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