Daughters may inherit mood disorders from their mothers, finds a new study published in the Journal of Neuroscience.

"Parents have large genetic and environmental influences on the offspring, known as intergenerational effects," the study authors wrote. "Specifically, depression has been shown to exhibit strong matrilineal transmission patterns. While intergenerational transmission patterns in the human brain are virtually unknown, this would suggest that the corticolimbic circuitry relevant to a wide range of processes including mood regulation may also show matrilineal transmission patterns."

The corticolimbic system includes the amygdala, hippocampus, anterior cingulate cortex, and vertromedical prefrontal cortex — parts of the brain that govern emotional regulation and processing, and play a role in mood disorders.

For the study, authors included 35 healthy families from a larger study not focused on the corticolimbic system and related behavior; parents were aged 33 to 48 and biological offspring were aged 5 to 13. Participants were divided among four parent-offspring groups, including 16 mother-daughter, 18 mother-son, 15 father-daughter, and 18 father-son pairs.

Authors administered behavioral assessments and parent-rating scales to measure adaptive and problematic behavior, such as aggression, anxiety, attention problems, depression, and hyperactivity, respectively. Both measures were meant to indicate “at-risk” behaviors, while authors conducted an additional analysis to compare group differences between male and female offspring.

Next, participants underwent magnetic resonance imaging to help authors better measure parent-offspring correlation in the corticolimbic circuity, and create brain maps that compared correlation coefficients between different parent-offspring groups.

The results revealed female-specific intergenerational effects on brain structure. Specifically, the authors wrote, "there were positive associations of regional [gray] matter volume between mothers and daughters greater than mother-son, father-daughter, and father-son groups." These findings suggest that a daughter's corticolimbic circuitry is associated specifically with that of her mother's.

Previous, and mostly animal, studies have suggested a similar association that female offspring are more likely than males to show changes in emotional regulating brain structures in response to maternal prenatal stress, lead author Fumiko Hoeft, an associate professor of psychiatry at the University of California, San Francisco, said in a press release. But until this study, Hoeft said few studies have linked the two streams of research.

"This is the first study to bridge animal and human clinical research and show a possible matrilineal transmission of human corticolimbic circuitry, which has been implicated in depression, by scanning both parents and offspring," she said. "It opens the door to a whole new avenue of research looking at intergenerational transmission patterns in the human brain."

According to study authors, this is also the first study to use MRI in both parents and their offspring to study intergenerational effects on brain structure. This could offer other researchers a potential new tool to not only better understand depression, but other neuropsychiatric conditions, including anxiety, autism, schizophrenia, and dyslexia.

However, the study has limitations, Hoeft said; "It does not differentiate between the potential effects of genetics, prenatal conditions, and postnatal conditions on the inheritance of brain structures." She and her team admit that it is difficult to pinpoint precise underlying mechanisms.

"Nonetheless, one may speculate that genetic, prenatal, and postnatal environmental factors and their interactions may underlay female-specific intergenerational patterns in depression symptoms, brain morphometry, and gene expression patterns in the corticolimbic circuity," the authors concluded.

Source: Hoeft F et al. Female-specific intergenerational transmission patterns of the human corticolimbic circuitry. Journal of Neuroscience. 2016.