Depression is a complex disease, and despite countless studies, scientists and physicians have not yet pinpointed any one singular cause for the disorder that affects an estimated 20 million Americans today. Many contributing factors foster the already pre-existing conditions within a person to manifest as depression. Recently depression research, according to the Mayo Clinic, has focused less on these contributing factors — such as bullying, divorce and an unhealthy diet — and instead have focused on what these "pre-existing conditions may be." This has led scientists to inquire about what conditions may make patients susceptible to entering depression, some of which may include past physical abuse, prescription medication interactions, death or loss of a loved one, major illness, substance abuse and genetics, to name a few.
Of high interest amongst the short, and hardly exhaustive, list above is genetics. Since the start of the genome project, the project dedicated to mapping the human genetic code, there has been an advent of genetic research to pinpoint specific genes to specific functions. In the past 20 years, research related to mental illness has focused on the genetic disposition of patients to develop depression. According to the Mayo Clinic, this research has stretched from looking at structural differences in the brain anatomy of patients with and without depression, to studying brain chemistry imbalances due to protein behaviors.
According to Stanford Medicine, we can be sure that genetics plays a role in depression because of studies involving twins, which demonstrates that "Heritability accounts for 40-50% [of depression], and might be higher for severe depression." What scientists are grappling to understand now is if there are instances in which depression is completely genetic or completely unrelated and instead only shaped by psychological or physical factors, considering that 50/50 split.
The case for "both" is strong. According to the structural differences mentioned above, "the hippocampus, a small part of the brain that is vital to the storage of memories, appears to be smaller in some people with a history of depression than in those who've never been depressed. A smaller hippocampus has fewer serotonin receptors." Serotonin is one of the many neurotransmitters that facilitates communication across different acting areas of the brain. These differences may not necessarily cause depression in a single person but may offer a breeding ground for an external aggravator to gain a foothold.
These footholds are best exemplified in instances where patients with depression also experience substance abuse. According to a trusted non-profit resource, "roughly 50 percent of individuals with severe mental disorders are affected by substance abuse." These numbers are the driving forces behind such genetic research. Though there is not a single gene responsible for depression, genetics is illuminating aspects of the disease that may translate into better therapies. In a published study in Neuropsychopharmacology, scientists in 2003 found a receptor protein ostentatiously involved in biochemical brain processes in patients undergoing depression and substance abuse. Again, it is important to understand that these proteins and genes do not act alone, but in concert with the wider biological system.
As leaders in substance abuse and depression, the physicians at Fairwinds Treatment Center are experts in Dual Diagnosis. Championed by Dr. M.K. (Khal) El-Yousef, who founded Fairwinds 25 years ago, dual diagnosis is a two-pronged treatment in therapy and pharmaceutical prescription to help patients address and resolve the root causes of their depression, substance abuse or eating disorders. This approach has made Fairwinds one of the top dual diagnosis treatment centers in the country.