Brain injuries: measuring consciousness by 'perturbing the brain'

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Main Category: Neurology / Neuroscience
Also Included In: Medical Devices / Diagnostics
Article Date: 15 Aug 2013 - 8:00 PDT Current ratings for:
Brain injuries: measuring consciousness by 'perturbing the brain'

Assessing consciousness in patients with severe brain trauma is a difficult challenge for doctors, as the injury effectively takes away any ability to blink, squeeze a hand or otherwise respond. But scientists have found a way to measure the brain's response to a magnetic pulse, helping them determine a person's level of awareness.

The researchers in Italy, led by Marcello Massimini, set out to find a reliable, objective way to distinguish an unconscious brain from a conscious one. Though many existing methods use brain imaging or electrical activity of neurons, Massimini says "that's not enough."

He notes that sometimes an unconscious brain can appear integrated, meaning groups of cells from different regions can activate to make a connected pattern.

Stimulating a sleeping person's brain, he says, can produce a wave of activity that "propagates like a ripple in water," even though the person is not conscious.

On the other side of the fence, the researchers say that around 40% of patients who are initially judged to be unresponsive are found later to possess a level of consciousness.

To measure consciousness, Massimini and his colleagues created the perturbational complexity index (PCI), which involves holding a magnetic coil to the skull and measuring the response. This transcranial magnetic stimulation (TMS) generates a pulse that sparks a response through the underlying neurons and propagates throughout the brain.

EEG readings were analyzed after pulsing unconscious brains with the magnetic coil.

By recording the brain's response by electroencephalography (EEG), the researchers then turned the information into a score between 0 and 1. The so-called information-rich responses - those distributed across the brain that are still individualized - receive higher scores, denoting a higher level of consciousness.

The researchers calibrated their system by using healthy patients in three different states: awake, deep sleep and under anesthesia, which served as a reference for unconsciousness.

For the healthy patients, they measured the highest unconscious score at 0.31 and the lowest conscious score at 0.44.

When they tested 20 people with brain damage who were believed to be in a state of partial wakefulness but who showed no signs of awareness, they observed low scores between 0.19 and 0.31.

Additionally, when Massimini and his team tested on two patients who had normal cognitive abilities (for example, they could shift their eyes) but were unable to move, they received PCI scores of 0.51 and 0.62, which rated at the same level as the healthy patients.

The researchers say that the index they have effectively created provides a scale of consciousness and unconsciousness that could be used as an "objective" test "at the bedside."

In an interview with Bloomberg, Marcello Massimini said:

"It will be very important to perform measurements right in the ICU in the acute phase to have an objective marker of what's happening and to track improvements occurring spontaneously or brought about by treatment.

If you have a number, you can start working towards an evidence-based treatment."

A team from Belgium recently discovered a simple method for testing coma patients involving resistance to eye-opening, but the index from Massimini and his colleagues could provide a measurable indicator for diagnosing levels of consciousness. Written by Marie Ellis
Copyright: Medical News Today
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A Magnetic Trick to Define Consciousness Kelly Servick, Science, published online 14 August 2013.

A Theoretically Based Index of Consciousness Independent of Sensory Processing and Behavior Marcello Massimini, et al., Science Translational Medicine, published online 14 August 2013.

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posted by Mark on 15 Aug 2013 at 11:12 am

This is an interesting study and approach. A few questions come to mind:

1) when sending such a ping request to the brain in a conscious person, does the person feel such a magnetic pulse?

2) Did the researchers test said device on themselves first before attaching it to patients?

3) if such stimulus reports the person is not conscious, they could be sleeping, or truly in a coma state...would this test be used to determine whether a person lives or dies?

If question 3 becomes a fact, and it could potentially be used to determine whether to keep someone on life supporting equipment or not, then I would have to say I have some objections to said test. As much as we think we know about the brain, we still don't know enough, and the decisions of life and death are taken up by persons assuming certain facts.

We don't know enough about the conscious or unconscious states, and for all we know, a coma could be an altered sense of reality, in a dream like world, but for that person they are alive, and breathing, in their mind, but perhaps this test says they're conscious.

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posted by Kevin K on 15 Aug 2013 at 8:25 am

How can you be awake and unconscious at the same time?

"...20 people with brain damage who were believed to be awake but completely unconscious..."

Editor's note: Thank for your comment, Kevin. Marcello Massimini, (lead author of the study) reported, "those who were believed to be in a vegetative state - awake but completely unconscious - got very low scores (between 0.19 to 0.31)."

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Link between race consciousness and blood pressure in black patients

Main Category: Hypertension
Also Included In: Psychology / Psychiatry
Article Date: 15 Aug 2013 - 1:00 PDT Current ratings for:
Link between race consciousness and blood pressure in black patients

Black patients preoccupied with racial concerns have higher blood pressure than those who aren't, according to results of new Johns Hopkins-led research. The findings suggest that heightened race consciousness could at least in part account for the disproportionately high rate of hypertension in black Americans - the highest prevalence of any group in the United States and one of the highest rates in the world.

"A preoccupation with race among blacks leads to hyper-vigilance, a heightened awareness of their stigmatized status in society and a feeling that they need to watch their backs constantly," says Lisa A. Cooper, M.D., M.P.H., a professor in the Division of General Internal Medicine at the Johns Hopkins University School of Medicine and senior author of the study described online in the American Journal of Hypertension. "African-Americans have higher blood pressure, and it has been difficult to explain why this is true. It doesn't appear to be genetic, and while things like diet, exercise and reduced access to health care may contribute, we think that a tense social environment, the sense of being treated differently because of your race, could also possibly explain some of what's behind the higher rates."

Cooper says the issue of such hyper-vigilance and race consciousness has drawn more public attention in the wake of the killing of Trayvon Martin, an unarmed black teenager, in Florida. Her own African-American son, she says, is very aware of his surroundings.

"It's stressful for him to walk around thinking at anytime someone might think he's dong something wrong just because of his race," she says. "That's just something he lives with. If you don't live with it, maybe it's hard to understand it. It's something people often don't want to talk about."

As part of ongoing research into doctor-patient relationships and racial disparities, Cooper and her colleagues surveyed 266 patients in urban health clinics in Baltimore between September 2003 and August 2005. Sixty-two percent of the patients were black. To test for race consciousness, they used the 2002 Behavioral Risk Factor Surveillance System "Reactions to Race" module developed by the U.S. Centers for Disease Control and Prevention. Patients - both black and white - were asked how often they thought about their race.

Two categories were created: Those who said they ever think about their race and those who said they never do. Half of the black patients responded that they "ever" think about it, and one in five white patients said they did.

When blood pressures were measured, being a race-conscious black patient was associated with significantly higher diastolic blood pressure (roughly five millimeters of mercury) and somewhat higher systolic blood pressure (some four millimeters of mercury) than black patients who were not preoccupied with race. There was no effect on blood pressure in race conscious white patients. Systolic blood pressure, the top number in a blood pressure reading, measures the force that pressure from the beating heart places on the arteries moving blood to the rest of the body, while diastolic blood pressure, the bottom number, indicates the pressure in the arteries when the heart rests between beats.

Cooper, director of the Johns Hopkins Center to Eliminate Cardiovascular Health Disparities, says it is well known that chronic stress can increase blood pressure. Similarly, she says tasks that require active coping efforts may increase heart rate and systolic blood pressure, while tasks that require quiet attentiveness and vigilance may lead to decreased cardiac output as well as increased diastolic blood pressure.

In addition to the link between race consciousness and blood pressure, Cooper's team found that whites who were race conscious were more likely to feel respected in the doctor-patient relationship than whites who were not concerned with race, though they were less likely to take their blood pressure medication as prescribed.

"Given the socially dominant status of whites in the United States, higher levels of race consciousness could reflect greater awareness of white privilege," the authors note in the study. "Another explanation, particularly among whites who reside in areas with a high black population, is that race consciousness reflects a heightened fear of victimization, an anxiety-provoking stressor. Scholars of critical race theory are still debating whether race consciousness enhances or adversely effects the health of whites."

Cooper notes that it can be stressful for black people to go shopping in a store and feel they are being watched extra closely. Equally stressful, she says, is for example, waiting a long time to be served at a restaurant, and being ignored, possibly because of one's race.

More research is needed to understand the biological consequences of race consciousness, including those related to stress, she adds, with a goal of developing interventions to help people effectively cope with environmental stressors.

"We need to help people of all races cope with race-related stress in a healthier way," she says.

Article adapted by Medical News Today from original press release. Click 'references' tab above for source.
Visit our hypertension section for the latest news on this subject.

This study is supported by grants from the National Institutes of Health's National Heart, Lung and Blood Institute (K24 HL083113, P50 HL0105187 and R01 HL069403).

Association of Race Consciousness With the Patient–Physician Relationship, Medication Adherence, and Blood Pressure in Urban Primary Care Patients

LaPrincess Brewer, M.D., M.P.H., who was a medical resident at Johns Hopkins Bayview Medical Center at the time of the study and is now a cardiology fellow at the Mayo Clinic, was the first author of the study. Kathryn A. Carson, Sc.M., of Johns Hopkins Bloomberg School of Public Health, also contributed to this study. doi: 10.1093/ajh/hpt116

Johns Hopkins Medicine

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'Link between race consciousness and blood pressure in black patients'

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