By Sandy Hemphill, Contributing Writer, BabyMed
A recent study of mothers, daughters, and their brain structures indicates the brain circuitry of mothers and daughters is much more alike than it is to any other members of the family. This finding puts a human perspective on previous studies that indicate the female offspring of female mice who experience stress during pregnancy are more likely than male offspring to have altered circuitry in the areas of the brain associated with emotions. The researcher behind the human study describes her work as one of only a few studies that attempt to link the two streams of research.
Dr. Fumiko Hoeft, an associate professor of psychiatry at the University of California, San Francisco, used magnetic resonance imaging (MRI) to map the brains of every biological member of 35 families free of mental and physical disorders. The MRI scans were targeted to the corticolimbic system, where grey matter volume (GMV) was measured.
The corticolimbic system processes the brain’s anticipation-reward responses to internal and external signals. This system of the brain recognizes and responds to emotional cues and influences how a person responds physically and mentally to any emotional trigger.
Brains: All in the Family
Hoeft’s study is the first of its kind to use brain scans to document how brain structure is passed along from parent to child. Of the study, Hoeft said, “This gives us a potential new tool to better understand depression and other neuropsychiatric conditions, as most conditions seem to show intergenerational transmissions patterns.”
What the scans revealed is:
- Similarities in GMV were most likely between mothers and daughters.
- Less likely between mothers and sons.
- Even fewer similarities existed between fathers and their children of either gender.
Brain structure alone doesn’t dictate who will develop psychiatric disorders such as depression but “anxiety, autism, addiction, schizophrenia, dyslexia, you name it -- brain patterns inherited from both mothers and fathers have an impact on just about all of them.” Also impacting development of disease or disorder are genetics, stress occurring before and after birth, and the environment in which the child lives.
IVF and “This Fantastic Opportunity”
Hoeft is turning to in vitro fertilization (IVF) to answer questions about the impact of other factors in addition to brain structure. Her next study is in its early stages but will explore the connection between genetics and brain structure in families where a child was conceived using one of three IVF scenarios:
- Homologous IVF -- Mother and father are biological parents although fertilization occurs outside the womb. In this subgroup, the child inherits genetic materials from both parents and experiences prenatal and postnatal influences from both biological parents.
- Donor Egg -- In this subgroup, the mother carries a child with the genetic blueprint of another woman and its own biological father. The child experiences the prenatal and postnatal influences of its birth mother and biological father.
- Surrogate Mother -- This subgroup consists of women giving birth to children who inherit genetics from a biological father and a biological mother who could not sustain the pregnancy herself. These children share the genetics of their biological parents but are subject to prenatal influences of their surrogate mothers.
Hoeft describes this study as “the very first time” medical researchers have been “able to examine, and hopefully distinguish between, the effects of genetics, prenatal environment and postnatal environment on brain function, structure, and cognitive function.”
Funding for Hoeft’s study targets only the IVF effect on the corticolimbic circuitry but “does not preclude our looking at other brain systems.” She has plans to examine “the language network, the reward system and different networks implicated in psychosis.” She says the ability to “cast a wide net” will bring “a lot of information and maximize this fantastic opportunity.”
Older Mothers and Daughters’ Depression
The findings of a study published in a 2015 issue of the Journal of Abnormal Psychology revealed that a mother’s age influences a daughter’s likelihood of developing depression by age 20.
Approximately 1,200 Australian daughters were followed for 20 years to see if their mother’s age at childbirth affected development of depression. The study found:
- Daughters born to mothers 30 to 34 years old had higher stress levels at age 20 than 20-year-old daughters of younger mothers.
- When mothers were 35 and older, daughters were more likely to experience stress, depression, and anxiety.
This study does not reveal and cause-and-effect relationship between mother’s age and daughter’s depression. The higher risk of depression in daughters of older mothers may be influenced by different value systems across the wider age gap, a mother’s advancing age when the daughter reaches adulthood, or increased worry on the part of the daughter for her mother’s fading health.
Sources:
Hoeft, F, et al. "Female-Specific Intergenerational Transmission Patterns of the Human Corticolimbic Circuitry."PubMed. JNeurosci (The Journal of Neuroscience) / Society for Neuroscience, 27 Jan. 2016. US National Library of Medicine / National Institutes of Health. Web. 12 Feb. 2016.
Preidt, Robert. "Depression More Common in Daughters of Older Mothers, Study Suggests."MedlinePlus. US National Library of Medicine / National Institutes of Health, 20 Nov. 2015. Web. 12 Feb. 2016.