That study might be not support the wild conclusion in the title.
They determined fluency in two languages (Spanish and Catalan) in people hospitalized in and around Barcelona. There are some hard-core Catalans that hardly --or even refuse to-- speak Spanish there, but not that many in Barcelona, but there are (many) people from other regions in Spain who are not fluent in Catalan, because they started working and living there a long time ago, when speaking Catalan simply was not needed, or perhaps still forbidden. These will be older, poorer and more frequently hospitalized. So they might simply be looking at two very different groups. Not a word about that in the abstract. I can't access the article.
If actively speaking two languages has an influence, I wouldn't expect much of a difference between Spanish and Catalan: they are close enough to be seen as dialects. They should test this on e.g. English/Urdu speakers or Hungarian/Rumanian.
They determined fluency in two languages (Spanish and Catalan) in people hospitalized in and around Barcelona. There are some hard-core Catalans that hardly --or even refuse to-- speak Spanish there, but not that many in Barcelona, but there are (many) people from other regions in Spain who are not fluent in Catalan, because they started working and living there a long time ago, when speaking Catalan simply was not needed, or perhaps still forbidden. These will be older, poorer and more frequently hospitalized. So they might simply be looking at two very different groups. Not a word about that in the abstract. I can't access the article.
If actively speaking two languages has an influence, I wouldn't expect much of a difference between Spanish and Catalan: they are close enough to be seen as dialects. They should test this on e.g. English/Urdu speakers or Hungarian/Rumanian.