When it comes to mental illness, the nature-versus-nurture debate is far from settled. But a new study published in the Journal of Neuroscience suggests that the part of the brain linked to depression may be passed down from mother to daughter.
In the January 2016 study, researchers found that the composition of the brain structure that plays a role in mood disorders was most similar between daughters and mothers. Multiple studies have shown that depression has a strong link between mothers and daughters, but this is the first study of its kind to prove it through brain scans.
The University of California, San Francisco researchers studied the brain MRI scans of people from 35 healthy families (none of the participants had depression) and found that the brain matter in the corticolimbic system was very similar between mothers and daughters.
The corticolimbic system, which is responsible for regulating emotions and moods, is more likely to be passed down from mothers to daughters than from mothers to sons or from fathers to either child. The corticolimbic system includes the amygdala, hippocampus, anterior cingulate cortex, and ventromedial prefrontal cortex, which are all regions that play a role in mood disorders like depression.
It's important to note that this doesn't mean moms are at fault if their daughters suffer from depression. Depression is a complex condition that's affected by many factors. The study is preliminary and limited because it doesn't take into account other factors that might affect brain structure, such as the prenatal experience and environmental factors.
"Many factors play a role in depression — genes that are not inherited from the mother, social environment, and life experiences, to name only three. Mother-daughter transmission is just one piece of it," lead author Dr. Fumiko Hoeft said in a statement. But the researchers hope this is a first step, if a small one, toward figuring out how mood disorders and other mental traits get passed down from generation to generation.