Can people lose their first language because they don't speak their mother tongue for a long time?

Yes, the simplest case is that you have lived in a non-native language area for a while, and when you come back, you find that some words can't be said at once, which is called vocabulary loss; In some cases, a person may even forget the syntactic rules of his mother tongue, which is often related to early immigration, family language or other extreme situations. This is a hot topic in linguistic research in recent years. There are many differences between the ability of mother tongue and other cognitive abilities, and it will not accompany you for life like learning to swim and counting (really? ), and we don't need to practice as often as we learn some special skills. The loss of mother tongue ability is also influenced by many different factors. Such research can help us understand how language is acquired and stored in the brain, how it differs from other cognitive functions, and even help us understand and treat aphasia patients.

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