Could fixing the body clock help people regain consciousness?

April 19, 2017

MINNEAPOLIS - For people with severe brain injuries, researchers have found that the rhythm of daily fluctuations in body temperature is related to their level of consciousness, according to a preliminary study published in the April 19, 2017, online issue of Neurology®, the medical journal of the American Academy of Neurology.

"Our study suggests that the closer the body temperature patterns of a severely brain injured person are to those of a healthy person's circadian rhythm, the better they scored on tests of recovery from coma, especially when looking at arousal, which is necessary for consciousness," said study author Christine Blume, PhD, of the University of Salzburg in Austria.

Circadian rhythms, which are rhythmic variations in body functions brought about by the body's internal clock, are the daily cycles that tell us when to sleep, wake or eat. This biological clock also regulates many of the body's other functions including temperature. It is set by environmental cues, like periods of daylight and dark.

In healthy people, daily variations in body temperature closely follow the sleep-wake cycle, the 24-hour daily sleep pattern controlled by the body's internal clock. Other studies have found that disruptions to the sleep-wake cycle may affect various aspects of health like the immune system and short-term memory. During a normal sleep-wake cycle, the body's core temperature fluctuates and can drop one to two degrees during the early morning hours.

For this study, researchers monitored 18 people with severe brain injuries, those with unresponsive wakefulness syndrome and those in a minimally conscious state. Unresponsive wakefulness syndrome, also known as a vegetative state, is when someone has awakened from a coma, is opening his or her eyes and having periods of sleep, but remains unresponsive. A minimally conscious state is when someone shows signs of awareness.

For one week, researchers continually monitored the body temperatures of participants with external skin sensors. With that temperature data, they were able to determine the length of the circadian rhythm for each person. Length of temperature cycles of participants ranged from 23.5 to 26.3 hours.

Researchers also evaluated the level of consciousness for each person with the Coma Recovery Scale-Revised, measuring things like response to sound and ability to open eyes with or without stimulation. They found that those who scored better on that scale had body temperature patterns that more closely aligned with a healthy 24-hour rhythm.

"This is the first time an association has been found between circadian variations in body temperature and arousal in brain-injured patients. Importantly, arousal is essential for consciousness," said Blume. "Circadian variations are something doctors should keep in mind when diagnosing patients. The time of the day when patients are tested could be crucial. Also, doctors may want to consider creating environments for patients that mimic the light patterns of night and day to help achieve a normal sleep-wake cycle. The hope is that this may help bring a person with a severe brain injury closer to consciousness."

The researchers tested bright light stimulation on eight participants for one week and found positive effects in two patients. Blume said that larger studies are needed to test the hypothesis that bright light is indeed beneficial for patients.

One limitation of the study was that magnetic resonance imaging (MRI) data was not available to evaluate the extent of brain damage, especially in the hypothalamus, the portion of the brain where the body clock is located.

Blume suggests that future studies look at the relationship between body temperature rhythms and other body rhythms like hormone patterns and rest-activity cycles.
-end-
To learn more about brain injury, visit http://www.aan.com/patients.

The American Academy of Neurology is the world's largest association of neurologists and neuroscience professionals, with 32,000 members. The AAN is dedicated to promoting the highest quality patient-centered neurologic care. A neurologist is a doctor with specialized training in diagnosing, treating and managing disorders of the brain and nervous system such as Alzheimer's disease, stroke, migraine, multiple sclerosis, concussion, Parkinson's disease and epilepsy.

For more information about the American Academy of Neurology, visit http://www.aan.com or find us on Facebook, Twitter, Google+, LinkedIn and YouTube.

Media Contacts:

Renee Tessman, rtessman@aan.com, (612) 928-6137
Michelle Uher, muher@aan.com, (612) 928-6120

American Academy of Neurology

Related Brain Articles from Brightsurf:

Glioblastoma nanomedicine crosses into brain in mice, eradicates recurring brain cancer
A new synthetic protein nanoparticle capable of slipping past the nearly impermeable blood-brain barrier in mice could deliver cancer-killing drugs directly to malignant brain tumors, new research from the University of Michigan shows.

Children with asymptomatic brain bleeds as newborns show normal brain development at age 2
A study by UNC researchers finds that neurodevelopmental scores and gray matter volumes at age two years did not differ between children who had MRI-confirmed asymptomatic subdural hemorrhages when they were neonates, compared to children with no history of subdural hemorrhage.

New model of human brain 'conversations' could inform research on brain disease, cognition
A team of Indiana University neuroscientists has built a new model of human brain networks that sheds light on how the brain functions.

Human brain size gene triggers bigger brain in monkeys
Dresden and Japanese researchers show that a human-specific gene causes a larger neocortex in the common marmoset, a non-human primate.

Unique insight into development of the human brain: Model of the early embryonic brain
Stem cell researchers from the University of Copenhagen have designed a model of an early embryonic brain.

An optical brain-to-brain interface supports information exchange for locomotion control
Chinese researchers established an optical BtBI that supports rapid information transmission for precise locomotion control, thus providing a proof-of-principle demonstration of fast BtBI for real-time behavioral control.

Transplanting human nerve cells into a mouse brain reveals how they wire into brain circuits
A team of researchers led by Pierre Vanderhaeghen and Vincent Bonin (VIB-KU Leuven, Université libre de Bruxelles and NERF) showed how human nerve cells can develop at their own pace, and form highly precise connections with the surrounding mouse brain cells.

Brain scans reveal how the human brain compensates when one hemisphere is removed
Researchers studying six adults who had one of their brain hemispheres removed during childhood to reduce epileptic seizures found that the remaining half of the brain formed unusually strong connections between different functional brain networks, which potentially help the body to function as if the brain were intact.

Alcohol byproduct contributes to brain chemistry changes in specific brain regions
Study of mouse models provides clear implications for new targets to treat alcohol use disorder and fetal alcohol syndrome.

Scientists predict the areas of the brain to stimulate transitions between different brain states
Using a computer model of the brain, Gustavo Deco, director of the Center for Brain and Cognition, and Josephine Cruzat, a member of his team, together with a group of international collaborators, have developed an innovative method published in Proceedings of the National Academy of Sciences on Sept.

Read More: Brain News and Brain Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.