Research suggests that bilingualism can slow the rate of
cognitive decline in older adults and even delay the onset of
symptoms of dementia1. Older adult bilinguals outperform
monolinguals on a range of executive functioning tasks including
inhibitory control, task switching, and working memory2. This is
known as the “bilingual advantage”. According to Ellen Bialystok,
the suppression of one language when using the other
strengthens frontal lobe functioning thus resulting in a cognitive
advantage for bilinguals2
.

However, the bilingual advantage has not been observed in
Welsh-English adults over 65 using behavioural tasks3. A possible
explanation is that for life-long balanced bilinguals switching
between languages is effortless and does not “exercise” the
frontal lobe functioning needed to demonstrate a bilingual
advantage.
The present study tested the hypothesis that learning Welsh as
an adult would facilitate a bilingual advantage later in life, i.e.
after age 65, IF the adult Welsh learners:
• Became highly proficient in Welsh
• Used Welsh frequently in their daily lives – thus requiring
English, the dominant first language, to be suppressed.