English-speaking and bilingual Mexican Americans recover better after stroke than their Spanish-only-speaking compatriots, according to a new study. It remains unclear whether this result is due to changes made by language in the brain or to other differences in the samples. But the findings raise the possibility that the way languages shape our brains may be far more important than is generally accepted.
A month ago, the strongest evidence ever for the impact of mother tongues on brain development was published. A comparison between native German and Arabic speakers found greater connections between the two hemispheres of the brain for Arabic speakers. Also, German speakers seem to have more developed language networks in the left hemispheres of their brains. The differences are thought to reflect the contrast in the demands placed on the brain by the two languages.
The study did not explore whether such differences affect capacities beyond what is necessary for the languages themselves. However, the study, now published in a new paper, shows that the impact may be real and significant, at least for those unfortunate enough to have a stroke at some point in their lives.
Earlier studies had found that the consequences of stroke were worse for Mexican Americans than for non-Hispanic white Americans. There are many possible explanations for this, ranging from genetic factors to unequal medical treatment, but Dr. Lewis Morgenstern attempted to test the possibility that language was a contributing factor.
How effective is language in healing?
Morgenstern and co-authors studied the recovery from stroke of 1,096 Mexican Americans in Corpus Christi, Texas, and excluded some of the other potential effects from the study. All people in the study were tested three months after the stroke. The authors compared their results in three areas: neurologic, covering topics such as muscle strength, speech, and coordination; thinking and memory skills; ability to perform daily tasks. The test was conducted by certified bilingual staff.
“Our study found that Spanish-only-speaking Mexican-Americans had worse neurological outcomes three months after having a stroke than Mexican-Americans who spoke only English or were also bilingual,” Morgenstern said in a statement. There was no significant difference in the other two measurements, but the difference in the neurological measurement was significant. Spanish speakers averaged seven points for stroke on a 44-point scale, while English and bilingual speakers averaged four.
Although the population selected for the study was relatively homogeneous, the sample groups were not exactly the same. Only Spanish speakers were older and less educated than English speakers. On the other hand, they were less likely to smoke. After the authors controlled for these differences, the gap in neurological recovery declined to 1.9 points, but remained significant.
While the authors state that this study is definitely not a subject that can be tested in randomized controlled trials, they state that further studies with larger samples are needed.
Spanish and English are more similar to each other than Arabic and German, so if the difference is indeed related to brain changes caused by language, there may be even greater potential for variation among different native speakers.
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