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!
Investigators may unlock mystery of how staph cells dodge the body's immune system
22.09.2017 | Cedars-Sinai Medical Center
Monitoring the heart's mitochondria to predict cardiac arrest?
21.09.2017 | Boston Children's Hospital
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
22.09.2017 | Life Sciences
22.09.2017 | Medical Engineering
22.09.2017 | Physics and Astronomy