Actively speaking two languages protects against cognitive impairment
This might be me being overly cautious here, but I would be wary of the political implications of the study.It's from an open University that's a project for lifelong learning funded as a public service in Catalonia - promoting the catalan language in the region is a key point of the project, so studies  finding out that bilingualism is something great to have raise red flags about the nationalist agenda behind it.To be clear, I'm not trying to make a point against catalan people or taking a position in any political side whatsoever. I'm just pointing out the potential for local context affecting the scientific method here.