Maternal Depression Leads to Brain Changes in Children
Megan Brooks
August 17, 2011 — Children who
grow up with a depressed mother, who probably is not as attentive as a
nondepressed mother, may develop an enlarged amygdala, the part of the brain
linked to emotional responses, a new study suggests.
In the study, researchers
observed significantly larger amygdala volume in 10-year-old children whose
mothers struggled with depression throughout their young lives compared with
their peers who had not been exposed to maternal depression.
Sonia Lupien, PhD, from the Mental
Health Institute of University of Montreal, Quebec, Canada, and colleaguesreport their
study online August 15 in Proceedings of the National
Academy of Sciences.
Enlarged amygdala volumes have
also been seen in adoptees initially raised in orphanages, the study team
notes.
Taken together, the findings
suggest that the developing amygdala may be very sensitive to the quality and
quantity of maternal care.
"Maternal depressive
symptomatology has been associated with reductions in overall sensitivity to
the infant and with an increased rate of withdrawn, disengaged behaviors,"
Dr. Lupien and her colleagues write.
The message, Dr. Lupien told Medscape
Medical News, is that it is "important to treat the depressed patient,
but also take into account the family unit."
"Many clinicians only
concentrate on the patient that they treat, but other members of the family may
also suffer from the depression of an adult (spouses and/or children),"
Dr. Lupien added.
"No individual is alone in
depression and it might be important to take care of the children as well as
the mother and/or father in order to prevent the effects of depression from
spilling over other family members."
Long-Term Consequences Unknown
Dr. Lupien and colleagues
measured hippocampal and amygdala volume as well as stress hormone
(glucocorticoid) levels in 17 children exposed to maternal depression since
birth and 21 who were not. All of the children were 10 years old at assessment.
They found larger left and
right amygdala volumes (P < .01) in the children exposed to
maternal depression since birth compared with children without this exposure.
They also observed a significant positive correlation between mothers' mean
depression score over the first 7 years of the child's life and her own child's
mean amygdala volume (P < .0001).
Hippocampal volumes did not
differ between children exposed or unexposed to maternal depression, which
isn't all that surprising, Dr. Lupien said.
Many studies, she explained,
have shown hippocampal atrophy in adults, but not children, who report exposure
to childhood adversity.
"This has led to the
'incubation hypothesis' whereby the effects of stress during childhood may only
be apparent during adulthood (they may take time to emerge). This would be why
we see hippocampal atrophy in adults exposed to early adversity but not in
children exposed to adversity," Dr. Lupien said.
The investigators also observed
increased salivary glucocorticoid levels (P < .05) in the
children of depressed mothers when they were presented with unfamiliar situations,
suggesting increased reactivity to stress in those children.
"The long term
consequences of this increased reactivity to stress are unknown at this
point," Dr. Lupien said.
Sensitive to Neglect
Medscape Medical News asked Nim Tottenham, PhD,
assistant professor of psychology, Department of Psychology, University of
California, Los Angeles, for her thoughts on this study.
Dr. Tottenham was involved in
the study, reported by Medscape Medical News, that found
enlarged amygdala volumes and difficulties in emotion regulation in a group of
children reared in orphanages (Dev Sci. 2010;13:46-61).
The current study, Dr.
Tottenham said, "is very similar to what we had published in children
adopted from orphanages (which is important), but I think what is most novel is
that these children had experienced a more 'species-typical' rearing
environment and yet showed the same phenotype."
"Taken together," Dr.
Tottenham said, "the studies are showing that the developing human
amygdala is highly sensitive to maternal neglect, whereas the hippocampus,
unlike in adults, fails to show an impact during childhood."
"A strength of the
paper," she said, "was that all the children were exactly 10 years
old and the mother's depression was well-characterized across those 10
years."
"I sincerely think,"
Dr. Lupien commented, "that developing interventions to help parents and
children deal with the stress associated with depression in one family member
could provide very positive results for all the family members, and society at
large."
The study was supported by
grants from the John D. and Catherine T. MacArthur Foundation, the Canadian Institutes
for Health Research, and Fonds de recherche en santé du Québec. The authors and
Dr. Tottenham have disclosed no relevant financial relationships.
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