Yes, I was indeed thinking of language attrition, but

in the framework of Chomsky's theory (See, Principles and parameters - Wikipedia ) about language acquisition rather than Jakobson's theory about language regression.  While Jakobson's theory bears largely on the loss of language due to disease, Chomsky's attempts to explain the amazing ease with which first languages are acquired by people before they reach puberty (about the age of 12 when brain lateralization is complete).  Chomsky's theory may also shed light on why, until the age of about 12, a person's language skills are relatively vulnerable to change (See, Can you lose your native language? - BBC Future).  

Maybe someone should use George Strait's song for the next edition of "聽歌練聽力":