Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Sudden death from stress linked to wonky signals in the brain

23.12.2004


Sudden cardiac death from emotional stress may be triggered by uneven signals from the brain to the heart, according to a study by University College London (UCL) scientists published in the January issue of Brain.



UCL researchers have discovered that a system which normally coordinates signalling from the brain to different parts of the heart may be disrupted in some people, making them vulnerable to potentially fatal abnormal heart rhythms during mentally taxing tasks or emotional events such as family gatherings.

This is particularly true of people who already have heart disease, but it is the brain that may be most responsible. The new study suggests that uneven brain activity, in a region where nerves link directly to the heart, seems to result in an uneven distribution of signals across the heart, which stops the heart from contracting normally.


Around a third of the 300,000 sudden cardiac deaths which occur each year in the US arise from a blood clot in a major artery, which leads to a fatal heart attack. Mental stress is thought to be responsible for a further 20 per cent of these deaths, but scientists have been baffled by the exact mechanisms by which stress can bring on a fatal short-circuiting of the heart.

In the UCL study, volunteers with a history of heart disease were given stressful mental tasks while their brain activity was monitored using PET imaging. Electrical waves travelling across their heart were monitored using electrocardiogram analysis. The study showed that stress-induced changes in electrical currents in the heart were accompanied by uneven activity within the lower brain, in an area known as the brainstem.

The brainstem is connected on the left and right side to the heart by nerve pathways, known as autonomic nerves. These autonomic nerves control heart rate during physical or mental activity.

To maintain a regular heartbeat, the electrical currents that travel across the heart and initiate the heartbeat should be smooth and even. If these electrical waves travel slower or faster in parts of the heart, this can result in a short circuit which leads to arrhythmia - an irregular heartbeat.

Normally, the output from the brainstem to the heart via left and right autonomic nerves is symmetrical and does not disrupt heart rhythm, even during stress. However, UCL scientists think that, in some cases, the autonomic nerves fire unevenly during stress, which disturbs the smooth electrical pattern across the heart and could ultimately induce an irregular, and eventually fatal, heartbeat.

Dr Peter Taggart from UCL`s Centre for Cardiology says: “Some people are at risk of sudden death from stress, mainly people who already have heart disease. In these cases the combination of heart and brain irregularities means that heart failure could occur during a stressful or emotional event like a family gathering or even a boisterous New Year party.”

“Efforts to prevent the development of potentially dangerous heart rhythms in response to stress have focused on drugs which act directly on the heart, but results have so far been rather disappointing. Our research focuses on what is happening upstream, in the brain, when stress causes these heart rhythm problems. The results so far are very encouraging.

“It may soon be possible to identify which people are particularly at risk and even to treat a heart problem with a drug that works on the brain.”

Dr Hugo Critchley from UCL’s Institute of Neurology says: “The next stage of our research is to explore how signalling from the brain becomes uneven. It seems that emotions and stress may particularly activate the right hemisphere in the upper brain, but this is usually balanced out into a symmetrical signal produced lower down in the brainstem, possibly though a mechanism that works as a protective balancing relay.

“Some patients with epilepsy produce strong one-sided brain activity during fits and may also show asymmetric changes in the heart, suggesting that the relay system is by-passed. In apparently healthy people, it is possible that massive amounts of stress may also overload the system so that the brain’s normal conversion to a balanced symmetric heart response is overcome, leading to arrhythmia.”

“Ultimately we would like to establish whether there might be a therapeutic target in the brain for people at risk of stress-induced heart problems. Some medicines already reduce emotional stress responses and help reduce the risk of sudden heart problems, but we hope to develop more selective treatments that eliminate the need to dampen emotional responses in order to reduce the risk of arrhythmia and sudden death.”

Jenny Gimpel | alfa
Further information:
http://www.ucl.ac.uk/media/archive/archive-release/?mentalstress
http://www.ucl.ac.uk

More articles from Health and Medicine:

nachricht Researchers release the brakes on the immune system
18.10.2017 | Rheinische Friedrich-Wilhelms-Universität Bonn

nachricht Norovirus evades immune system by hiding out in rare gut cells
12.10.2017 | University of Pennsylvania School of Medicine

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Osaka university researchers make the slipperiest surfaces adhesive

18.10.2017 | Materials Sciences

Space radiation won't stop NASA's human exploration

18.10.2017 | Physics and Astronomy

Los Alamos researchers and supercomputers help interpret the latest LIGO findings

18.10.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>