I am all involved in this subject, researching for my Final Project in TEFL.
Mainly I came to different conclusions:
- it is valuable to be bi/tri/multilingual.
- researchers suggests that bilingualism may delay the onset of
age-related dementia, including Alzheimer’s disease, by up to four
years. Although scientists don’t know why bilingualism creates this
“cognitive reserve,” some theorize that speaking two languages may
increase blood and oxygen flow to the brain and keep nerve connections
healthy—factors thought to help ward off dementia.
- bilingualism is extremely widespread and is the norm in today's world.
More recently, scientists have discovered that bilingual adults have
denser gray matter (brain tissue packed with information-processing
nerve cells and fibers), especially in the brain’s left hemisphere,
where most language and communication skills are controlled. The effect
is strongest in people who learned a second language before the age of
five and in those who are most proficient at their second language. This
finding suggests that being bilingual from an early age significantly
alters the brain’s structure.