Written by: Kevin Cann
Depression is still often looked at by the masses as a state of mind that we can just simply snap right out of. I am writing this article today in hopes of educating as many people as I can regarding the true nature of depression. According to researchers at Stanford University the cause of depression is attributed 50% to genetics, and the other 50% attributed to other factors. This conclusion was drawn on research with identical and non-identical twins as well as looking at adopted children with a predisposition to depression (http://depressiongenetics.stanford.edu/mddandgenes.html ).
Diseases such as Alzheimer’s, Parkinson’s, and even cancer have ties to our genetics. We do not tell people with these diseases to just “snap out of it”, because it is not that simple. The same can be said about depression. Evidence has been mounting showing disruption in the hypothalamic-pituitary adrenal axis (HPA) in those that suffer from depression. Researchers decided to look at this section of the human brain because depression is also linked to cognitive decline on top of the emotional instability. What researchers have been discovering is game changing.
Research is beginning to show deficits in glucocorticoid receptor (GR) mediated negative feedback. This would make sense in light that increased stress leads to increased rates of depression. Our glucocorticoids are a group of our stress hormones, with cortisol being the most popular. GR’s are responsible for binding to the stress hormones and relaying their messages to cells. When there are deficits in the GR, the stress hormone’s signal is not read and relayed and we need an increased level of that same hormone to get the message across. One gene in-particular is being linked to the decreased ability someone has in managing stress and it is classified as the NR3C1 gene. Interestingly enough in rats maternal behavior can alter another gene, NGF1-A, which controls GR activity (http://www.ncbi.nlm.nih.gov/pubmed/19089807 ). This would explain how stress can lead to epigenetic changes that lead to us becoming depressed.
That study was done on rats, so let us look at a study that was performed on humans. Researchers looked at pregnant mothers with treated and untreated depressive disorders and looked at the methylation status of the NR3C1 gene. They concluded by stating that newborn methylation status of NR3C1 was effected by the mother’s mood during the third trimester of pregnancy (http://www.landesbioscience.com/journals/epigenetics/OberlanderEPI3-2.pdf ).
Why would the mother’s mood directly affect the child’s mood and predispose him or her to negative emotional well-being later in life? Could there really be a survival benefit to this? The time in utero and early on in life is a critical period for CNS development. Some newborns develop emotional resilience during this time and others develop an increased risk for mental illness (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2965301/ ). Perhaps this is evolution trying to figure out the best way to handle the stressors of modern society?
Serotonin is our neurotransmitter responsible for our mood. Low levels are associated with increased risk of depression, anxiety, and irritability. In fact, most anti-depressant medications work upon this pathway to try to alleviate the symptoms associated with anxiety and depression. Serotonin also plays a critical role in gene expression in helping us deal with stress.
Rats that are groomed more from their mothers show increased levels of serotonin. These increased levels of serotonin increase NGF1-A gene expression and they show lower levels of glucocorticoids, a group of stress hormones, later in life (http://www.nature.com/neuro/journal/v12/n3/fig_tab/nn0309-241_F1.html ). Knowing that serotonin plays a critical role in the expression of favorable genes to assist us in managing stress, we need to make sure that we do not become deficient in this important neurotransmitter. This makes managing stress, sleeping, and eating a diet high in nutrient dense food important as they all play critical roles in serotonin production, and poor sleep, food choices, and increased stress levels can actually deplete us of serotonin.
Depression is not just a frame of mind that we can just snap out of. Just like other diseases there is a genetic component to it. Our mother’s mood during pregnancy as well as our genetic lineage predispose us to either emotional resiliency or increased risk of mood disorders. The good news is that just because we are genetically predisposed to depression doesn’t mean that these genes need to express themselves. Our epigenome is an amazingly adaptive machine and we can take part in lifestyle behaviors that will quiet our negative genes and allow us to express positive mood genes. This includes sleeping well, eating a healthy diet of nutrient dense foods, having quality social relationships, managing stress, and getting adequate sunlight. Following those lifestyle rules will not only help with depression, but with other ailments as well.