Published on November 28, 2014 by David Sack, M.D. in Where Science Meets the StepsIt’s a finding that may one day help lift the spirits of millions: Researchers at Northwestern University announced that they have created a simple blood test that appears to diagnose major depressive disorder in adults. It does this by identifying nine blood biomarkers associated with the illness. Not only that, the researchers were able to show that these markers changed over an 18-week course of cognitive behavioral therapy (CBT), giving us our first biological, measurable proof that CBT, a type of psychotherapy that’s popular in depression treatment, alters the biological expression of the disease. The actions of the biomarkers also allowed the researchers to predict who would respond best to the treatment and even to indicate who has a tendency toward depression. It’s a lot of good news in one package, and it may be of special importance to those struggling with addictions to drugs and alcohol. That’s because depression and substance use disorders so often go hand in hand. The National Alliance on Mental Illness notes that as many as a third of those with mental illnesses such as depression also experience substance abuse. It’s not always clear which came first – in other words, did the depression lead to the drug or alcohol use, or did the use lead to depression? – but what is known is that each makes the other worse. Conversely, improving one can help the other.
Depression Often Undiagnosed
But do we need a blood test to tell us who is depressed? It might seem that those suffering from major depression would be all too aware they are doing so, but the reality is that major depressive disorder, also known as clinical depression, often goes undiagnosed. A 2012 study estimates that 12.5 percent of primary care patients have major depressive disorder in any given year, but less than half of those cases are recognized clinically. Currently, treatment professionals must rely on their observations and the patient’s own input to determine who has major depression, believed to affect 6.7 percent of U.S. adults each year. That’s especially problematic for those with substance use disorders, which can mask depression symptoms. For example, someone drinking heavily may be unaware that their depression springs from a source other than the drinking itself. And what does depression come from? It differs by the person, of course, but is believed to be caused by a combination of psychological, biological, genetic and environmental factors. Treating it has largely come down to trial and error, and what works for one person may not work for another. What is so encouraging about the new blood test is that it appears to promise a way to track improvement once treatment starts and to determine beforehand who will respond best to which course of action. This means that treatment for depression may one day be individualized on a level once undreamed of.
Evaluating Other Treatment Options
The researchers behind the blood test conclude their paper with a call for more study using a larger population, and it will be fascinating to see how blood biomarkers might be affected by depression treatment regimens beyond CBT. A variety of options exists for treating depression and more are added with each year – among them, transcranial magnetic stimulation (a type of noninvasive brain stimulation), problem-solving therapy, exercise therapy, and newer and more effective antidepressants, to name just a few. We may soon be bypassing the trial and error of treatment options and proceeding straight to what works best to eliminate depression. For the person struggling with both addiction and depression, this may mean less time for substance use to damage body, mind and relationships and a better chance of long-term recovery.