The Connection Between Diabetes and Mental Illness

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Chronic illnesses come with their fair share of both physical and emotional burden. In fact, people living with chronic illnesses are 2 to 3 times more likely to have depression. It’s easy to assume the depression is caused by the emotional impact a chronic condition can have on a person’s quality of life, but new research suggests that for diabetes, the connection to depression may be more closely rooted in genetics.

Diabetes and depression

Thomas Willis was an English doctor who coined the term ‘mellitus’ to ‘diabetes mellitus’ after discovering that the urine and blood of diabetic patients held a sweetness not present in healthy people. He speculated that diabetes was caused by “long sorrow and other depressions.” He certainly wasn’t the last to wonder about this connection.

A study published by researchers at the Harvard School of Public Health in 2010 sought to investigate this long-speculated link between diabetes and depression. Researchers collected data based on questionnaires about participants’ health practices and their medical history. 65,381 women participated in this study ages 50 to 75 and they were followed up with for the next ten years. After analyzing the data, researchers concluded there was "growing evidence that depression and diabetes are closely related" with the associations separate from sociodemographic, diet, and lifestyle factors. The women with diabetes had a 29 percent higher risk of developing depression compared to women without diabetes.

Now, scientists have found that this connection may be genetic in nature. In a new report, scientists found that a gene called “DISC1” that had been identified and known as a gene that plays a significant role in mental health disorders like schizophrenia, bipolar disorder, and depression also influences the functioning of pancreatic beta cells – cells vital in producing insulin to maintain normal blood glucose levels in our bodies.

They found that the presence and alterations of gene “DISC1” mean there is a greater genetic risk for both mental health disorders and diabetes.

One little gene “can play multiple roles in the body”

To investigate this gene’s effect on our bodies both mentally and physically, researchers looked at how the “DISC1” gene worked in mice. They took one group of mice and genetically disrupted the gene only in their pancreatic beta cells and compared it to a second group of control mice. By disrupting this gene in the cells of the mice from group 1, they found the gene showed increased beta cell death, less insulin secretion, and impaired glucose regulation – in short, all the effects of diabetes were present.

They found this particular gene works by controlling a specific protein and that by inhibiting this protein, the effects of diabetes were lessened and the survival of beta cells was improved.

Their findings have been published in the FASEB journal with the editor-in-chief commenting, “The connections between these disorders may be surprising, but we have known for a long time that a single protein or gene can play multiple roles in the body.”

What this means for patients

While many comorbidities exist with diabetes, mental health coupled with diabetes can be particularly destructive to not just the individual living with the conditions but to society and our healthcare systems as well. If mental problems like depression or schizophrenia are overlooked when treating people with diabetes, no matter how great a healthcare provider might be, the individual is still at risk for low drug adherence and participating in risky behavior – compromising their ability to self-manage their condition. Although people with diabetes have a 2 times greater likelihood of having major depressive disorder, only about one-third of patients receive a diagnosis and treatment.

With these new findings tying one culprit to both diabetes and mental disorders, education is key to begin changing the standard of care for diabetes to include a heavier focus on diagnosing and treating the mental problems that may arise.

Taking care of your body means taking care of your mind, too.