Now, a new study has revealed that both
maternal depression and a common kind of antidepressant are two big
environmental issues, which can alter when this learning phase begins in
children – ultimately affecting their ability to learn how to speak.
Researcher from the University of British
Columbia, Harvard University and the Child & Family Research Institute have
revealed that treating maternal depression with a class of antidepressants
called serotonin reuptake inhibitors (SRIs) help to speed up the newborn’s
ability to grasp and understand the sights and sounds of their native language.
Conversely, untreated maternal depression ultimately delayed this period
of language acquisition.
According to the scientists, this phase of
cognitive development begins before a baby is even born – meaning their
prenatal environment is extremely important.
“My work and the work of a lot of other people
have shown that we develop in the womb ready to learn any of the world’s
languages,” Janet Werker, a professor in the department of psychology at the
University of British Columbia and the study’s lead author, told FoxNews.com.
“We start out universal listeners, ready to learn what languages we hear
and see.”
Werker explained that during this language
learning period, newborns are able to differentiate between the characteristics
of their native language and the characteristics of languages of foreign
speakers. This window of learning eventually closes though, typically
around 8 months after birth.
Once the window closes, babies stop paying
attention to sounds they do not need and lose the ability to discern between
verbal cues that are not utilized in their native language.
“For example, when it comes to the difference
between [the words] ‘raw’ and ‘law,’ you as an English speaker can hear that
distinction,” Werker said, “but a Japanese adult cannot. However, a
Japanese baby can.”
Under most circumstances, the timing of this
language attuning phase is tightly controlled by simple maturation, Werker
said. In previous research, she analyzed healthy babies who were born up
to three months prematurely wondering if whether early exposure to broadcast
speech would accelerate the timing of mastering their native language.
However, the results showed that the age of conception rather than the
age of the baby’s birth dictated when this window of learning opened and closed
– meaning the timing is fairly standard for each child.
While the language acquisition phase is
seemingly pretty structured, the researchers still wanted to better understand
environmental factors they might alter its timing. Werker and her
colleagues studied three groups of mothers and their children – who were
suffering from maternal depression but not receiving treatment, moms who were
taking SRIs to treat their depression, and moms who did not exhibit depression
symptoms.
Once the mothers’ babies were born, the
researchers examined their eye movements and heart rates when they watched and
listened to videos of native and foreign languages – allowing them to determine
when language attuning had closed. Each baby was analyzed at three
intervals – six and 10 months of age, as well as measuring heart rates of
unborn babies responding to languages at 36 weeks in the uterus.
“The results of course showed that exposure to
anti-depressant medication in utero, seemed to accelerate this window of
opportunity,” Werker said. “If they had been exposed to SRIs in utero,
the babies were able to attune to speech differences earlier. Conversely,
babies’ mothers who were depressed and were not on SRIs – they started this
attuning later.”
Because of previous research showing that this
learning period predicts vocabulary acquisition later in life, Werker said that
it is important for mothers to be aware of environmental factors such as these
that may have effects. However, their study is not meant to tell mothers what
to do during pregnancy, she said.
“Depression is complicated,” Werker said.
“What we don’t want to do is make depressed mothers feel worse than they
already feel. The fact is that pregnancy can cause depression, so we want
to help inform so that mothers are making the very best choices they can.”
Given the results, the researchers noted that
it is likely that other factors may also accelerate or delay this process –
meaning much more research is needed.
“Development is occurring all the time,”
Werker said, “and precursors to language development are happening long before
babies produce their first word. SRI medication and maternal depression
seem to be among that class that change the timing. There are other types of
experiences –these are not the only ones that can change that timing.
It’s important to study these questions at this very precise level so
that we can drill down and specify more precisely exactly what types of
environmental experiences will have an impact.”
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