Selecting the Best Anti-depressant
By Drs. David Niesel and Norbert Herzog
People with depression sometimes need drugs to help them cope. The issue becomes how to choose among the many drugs that work in slightly different ways for each individual patient's situation. However, even a drug chosen very carefully may take several weeks or months of use before it is discarded as not working. This then begins a lengthy trial and error process with a series of drugs to find the right medication and the right dose. There is new hope in a relatively simple blood test that could identify the best drugs for that person, eliminating the time involved in the sequential testing of drugs.
Communication between nerve cells is mediated by molecules called neurotransmitters and among them, serotonin and norepinephrine are associated with depression. Most anti-depressants work by affecting these neurotransmitters. Scientists have discovered that some people with depression test positive for inflammation and generally require more aggressive therapy immediately. The blood test being used measures for inflammation by identifying key biomarkers. These biomarker proteins are called MIF and the IL-1beta. High levels of stress can cause our immune system to produce these inflammation markers, which interfere with how some of the most common anti-depressants work. We have known for some time that our response to stress and our immune system are interconnected and help protect us from external threats. Stress activates key pathways of the immune system that result in the release of these inflammatory proteins that turn on your body's defense mechanisms to help defend you against whatever is causing your stress. Studies of people with depression have revealed that their brain's immune cells show a high level of inflammatory signals compared to that seen in the brains of others without depression.
The greater the inflammatory response to a stressor, the more likely a person is to suffer depression in the months that follow. Interestingly, the stress response that produces the inflammatory signals generally take place in other areas of the body. These inflammatory signals can travel through the body, eventually being transmitted to the brain. The presence of these signals has been shown in experimental models to lead to altered behavior. These results clearly argue for regular cross talk between two major systems in our bodies - our immune system and our brains.
Studies have also shown that the genes important in depression also play a role in our immune system. This means that depression also affects our immunity. These inflammatory signals also affect how neurotransmitter communication occurs between neurons in the brain. Once in the brain, the inflammatory response can influence neurotransmitter systems that can ultimately affect brain functions that can change behavior, especially behaviors leading to decreased motivation and increased anxiety. These behavioral changes are associated with several psychiatric disorders including depression. Inflammation reduces the therapeutic effects of certain anti-depressants by interfering with their ability to restore the delicate balance of neurotransmitters. Much more work is needed but if this test proves to be reliable, patients with depression who have high levels of inflammation can be identified and their treatments modified increasing the chances for a faster successful treatment.
Medical Discovery News is hosted by professors Norbert Herzog at Quinnipiac University, and David Niesel of the University of Texas Medical Branch. Learn more at www.medicaldiscoverynews.com.