We know that depression runs in families. But it is only very recently that we are beginning to know how and why. With new research, medical professionals are revisiting the question: is depression genetic or environmental? And if depression is genetically determined, is it possible to break the cycle? A deeper understanding of the causes of depression, including both its genetic and environmental determinants, as well as their interplay, may help us better prevent and more effectively treat depression.
An Age-Old Question Reinvigorated
There is a longstanding fascination surrounding the dialectics between nature and nurture—a relationship that has preoccupied modern medicine for decades. By way of astounding advances in the field of genomics, many serious genetic illnesses and afflictions can now be traced back to a specific catalyzing gene through high-throughput DNA sequencing. However, science still actively struggles to reconcile the mysterious links between the mind and the body as new research continues to illuminate the manifold ways in which emotional, environmental, and even spiritual conditions alter the ways in which genetic predispositions manifest—or fail to do so.
Dr. David Hunter of Harvard University posits that “scientists are [actively] becoming better at blending methodologies and reaching across disciplines to strengthen their research efforts” when it comes to integrating environmental and behavioral data with traditional genetic analysis. But boundless research remains to be conducted as the technology of both genomics and epigenetics continues to break new ground.
Is Depression Environmental or Genetic?
Extensive research suggests that depression is both environmental and genetic. Our experience and environmental conditions definitively contribute to depression. These factors include: childhood maltreatment, negative family relationships, and parental divorce, financial instability, poor diet and lack of exercise, loneliness, and other stressful life events. While the risk of depression is elevated in the immediate aftermath of environmental adversities, the effects of adversity can persist throughout our lives.
There is now robust literature also implicating genetic factors in the etiology of depression. Depression is known to run in families. Edward Bullmore of The Guardian states that “the background risk of depression in the general population is about one in four – each of us has a 25% chance of becoming depressed at some point in our lives. And if your parents have been depressed, your risk jumps by a factor of three.”
Twin studies, which allow for simultaneous quantification of genetic and environmental influences, suggest that depression is moderately heritable. Even though they have almost no difference in their DNA, if one identical twin develops depression, the other twin frequently doesn’t. Specifically, twin studies have estimated that approximately 40% of the variation in the population risk of depression is attributable to genetic variation.
In recent years, the combination of advances in our understanding of human genomic variation (e.g., Human Genome Project; HapMap Project; 1,000 Genomes Project) and cost-effective genotyping techniques have led to extraordinary growth in molecular genetic studies of depression. New genomewide association studies (GWAS) have been used to examine over a million genomic variants known as single nucleotide polymorphisms (SNPs) for their association with depression. There are at least 44 genes, out of the 20,000 genes comprising the human genome, which contribute to the transmission of risk for depression from one generation to the next. Many of these genes are known to play important roles in the biology of the nervous system. This fits with the basic idea that disturbances of the mind must reflect some underlying disturbance of the brain.
MidCity TMS is Here to Help
Although genetic studies don’t prove that depression is “all in the brain” or that psychological treatment is not warranted, they do remind us that depression is fundamentally a condition that involves a dysfunctional brain. Therefore, the treatments that often work best, such as TMS (transcranial magnetic stimulation), directly impact the brain. TMS is a safe and non-invasive way to help stimulate the brain using magnetic pulses.
MidCity TMS is proud to help patients treat and manage their depression by providing expert and compassionate transcranial magnetic stimulation (TMS) services. Read more about the science behind depression on our blog and contact us today to begin your or your family’s healing journey.