Depression can heighten the risk for heart disease, but the effect of antidepressant use revealed by the study is separate and independent from depression itself, says first author Amit Shah, MD, a cardiology fellow at Emory University School of Medicine. The data suggest that antidepressants may combine with depression for a negative effect on blood vessels, he says. Shah is a researcher working with Viola Vaccarino, MD, PhD, chair of the Department of Epidemiology at Emory's Rollins School of Public Health.
The study included 513 middle-aged male twins who both served in the U.S. military during the Vietnam War. Twins are genetically the same but may be different when it comes to other risk factors such as diet, smoking and exercise, so studying them is a good way to distill out the effects of genetics, Shah says.
Researchers measured carotid intima-media thickness – the thickness of the lining of the main arteries in the neck -- by ultrasound. Among the 59 pairs of twins where only one brother took antidepressants, the one taking the drugs tended to have higher carotid intima-media thickness (IMT), even when standard heart disease risk factors were taken into account. The effect was seen both in twins with or without a previous heart attack or stroke. A higher level of depressive symptoms was associated with higher IMT only in those taking antidepressants.
"One of the strongest and best-studied factors that thickens someone's arteries is age, and that happens at around 10 microns per year," Shah says. "In our study, users of antidepressants see an average 40 micron increase in IMT, so their carotid arteries are in effect four years older."
Antidepressants' effects on blood vessels may come from changes in serotonin, a chemical that helps some brain cells communicate but also functions outside the brain, Shah says. The most commonly prescribed antidepressants are selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine (Prozac), which increase the level of serotonin in the brain. Other types of antidepressants also affect serotonin levels, and antidepressants can act on other multi-functional brain chemicals such as norepinephrine.
In the study, researchers saw higher carotid IMT in both participants who used SSRIs (60 percent of those who took antidepressants) and those who used other types of antidepressants.
Most of the serotonin in the body is found outside the brain, especially in the intestines, Shah notes. In addition, serotonin is stored by platelets, the cells that promote blood clotting, and is released when they bind to a clot. However, serotonin's effects on blood vessels are complex and act in multiple ways. It can either constrict or relax blood vessels, depending on whether the vessels are damaged or not.
"I think we have to keep an open mind about the effects of antidepressants on neurochemicals like serotonin in places outside the brain, such as the vasculature. The body often compensates over time for drugs' immediate effects," Shah says. "Antidepressants have a clinical benefit that has been established, so nobody taking these medications should stop based only on these results. This isn't the kind of study where we can know cause and effect, let alone mechanism, and we need to see whether this holds up in other population groups."
Jennifer Johnson | EurekAlert!
What does congenital Zika syndrome look like?
24.03.2017 | University of California - San Diego
23.03.2017 | Technische Universität München
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
24.03.2017 | Earth Sciences
24.03.2017 | Health and Medicine
24.03.2017 | Earth Sciences