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#AHA17 highlight: cardiac pacemaker cells

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schizophrenia

Big data with heart, for psychiatric disorders

Imagine someone undergoing treatment by a psychiatrist. How do we know the treatment is really working or should be modified?

To assess whether the patient’s condition is objectively improving, the doctor could ask him or her to take home a heart rate monitor and wear it continuously for 24 hours. An app connected to the monitor could then track how much the patient’s heart rate varies over time and how much the patient moves.

Heart rate variability can be used to monitor psychiatric disorders

MD/PhD student Erik Reinertsen is the first author on two papers in Physiological Measurement advancing this approach, working under the supervision of Gari Clifford, interim chair of Emory’s Department of Biomedical Informatics.

Clifford’s team has been evaluating heart rate variability and activity as a tool for monitoring both PTSD (post-traumatic stress disorder) and schizophrenia. Clifford says his team’s research is expanding to look at treatment-resistant depression and other mental health issues.

For clinical applications, Clifford emphasizes that his plans focus on tracking disease severity for patients who are already diagnosed, rather than screening for new diagnoses. His team is involved in much larger studies in which heart rate data is being combined with physical activity data from smart watches, body patches, and clinical questionnaires, as well as other behavioral and exposure data collected through smartphone usage patterns.

Intuitively, heart rate variability makes sense for monitoring PTSD, because one of the core symptoms is hyperarousal, along with flashbacks and avoidance or numbness. However, it turns out that the time that provides the most information is when heart rate is lowest and study participants are most likely asleep, or at their lowest ebb during the night.

Home sleep tests generate a ton of information, which can be mined. This approach also fits into a trend for wearable medical technology, recently highlighted in STAT by Max Blau (subscription needed).

The research on PTSD monitoring grows out of work by cardiologists Amit Shah and Viola Vaccarino on heart rate variability in PTSD-discordant twin veterans (2013 Biological Psychiatry paper). Shah and Vaccarino had found that low frequency heart rate variability is much less (49 percent less) in the twin with PTSD. Genetics influences heart rate variability quite a bit, so studying twins allows those factors to be accounted for. Read more

Posted on by Quinn Eastman in Heart, Neuro Leave a comment

Unlocking schizophrenia biology via genetics

Kristen Thomas, PhD, now a postdoctoral fellow at St Jude Children’s Research Hospital

Schizophrenia genetics and its complexities are beginning to yield to large genome-wide studies. One of the recently identified top risk loci, miR 137, can be seen as a master key that unlocks other doors. The Mir 137 locus encodes a micro RNA that regulated hundreds of other genes, and several of those are also linked to schizophrenia.

Earlier this month, Emory’s chair of cell biology Gary Bassell and former graduate student Kristen Thomas published a paper in Cell Reports analyzing how perturbing Mir 137 affects signaling in neurons. Inhibiting Mir 137 blocked neurons’ responses to neuregulin and BDNF, well-known growth factors.

“We think a particularly interesting aspect of our paper is that it links miR137, neuregulin and ErbB4 receptor: three molecules with known genetic risk for schizophrenia,” Bassell writes. Read more

Posted on by Quinn Eastman in Neuro Leave a comment

Neuroscientists show hippocampus also has important role in emotional regulation

A region of the brain called the hippocampus is known for its role in memory formation. Scientists at Yerkes National Primate Research Center, Emory University are learning more about another facet of hippocampal function: its importance in the regulation and expression of emotions, particularly during early development.

Using a nonhuman primate model, their findings provide insight into the mechanisms of human psychiatric disorders associated with emotion dysregulation, such as PTSD (post-traumatic stress disorder) and schizophrenia. The results were published online recently by the journal Psychoneuroendocrinology.

“Our findings demonstrate that damage to the hippocampus early in life leads to increased anxiety-like behaviors in response to an unfamiliar human,” says research associate Jessica Raper, PhD, first author of the paper. “However, despite heightened anxious behavior, cortisol responses to the social stress were dampened in adulthood.”

The hormone cortisol modulates metabolism, the immune system and brain function in response to stress. Reduced hippocampal volume and lower cortisol response to stressors have been demonstrated as features of and risk factors for PTSD, Raper says. Also, the dampened daily rhythms of cortisol seen in the nonhuman primates with hippocampal damage resemble those reported in first-episode schizophrenia patients.

Follow-up studies could involve temporary interference with hippocampus function using targeted genetic techniques, she says. Read more

Posted on by Quinn Eastman in Neuro Leave a comment

Oxytocin receptor levels predict comforting behavior in prairie voles

Different levels of a receptor for a hormone involved in social bonding may explain individual variation in offering comfort during stressful situations. Like humans, animals console each other in times of distress: monkeys hug and kiss, and prairie voles groom each other.

James Burkett, PhD

James Burkett, PhD

Emory postdoc James Burkett described his research on voles at a press conference on “The Neuroscience of Emotion and Social Behavior” at the Society for Neuroscience meeting in San Diego on Sunday. Here are Video (Burkett’s part is roughly from 4:50 to 9:00) and the scientific abstract.

Burkett’s presentation, on oxytocin-dependent comforting behavior in prairie voles, outlined an extension of his graduate work with Larry Young at Yerkes National Primate Research Center, which was published in Science in January 2016 and impressed oxytocin skeptic Ed Yong. Burkett, now in Gary Miller’s laboratory at Rollins School of Public Health, also masterminded a Reddit “Ask me anything” in February.

The rest of the Society for Neuroscience press release:

Previous research indicates oxytocin—a hormone that promotes social and maternal bonding—acts in the anterior cingulate cortex (ACC) of the prairie vole brain to encourage consoling behavior. In humans, the ACC activates when people see others in pain. Some degree of personal distress motivates comforting behaviors, but too much actually makes animals (including humans, chimpanzees, and rats) less likely to offer comfort.

Read more

Posted on by Quinn Eastman in Neuro Leave a comment

NMDA receptors: triple-quadruple axel

NMDA receptors are saddled with an unwieldy name, but they are some of the most important* signaling molecules in the brain, both for learning and memory and in neurological and psychiatric diseases.

Kasper Hansen, a postdoc from Stephen Traynelis’ lab who is establishing his own at the University of Montana, is lead author on a recent paper in Neuron, which could spur research on NMDA receptors’ pharmacological properties.

The NMDA receptors in the brain are actually mix-and-match assemblies of four subunits, and most of the time in the brain, three different proteins come together to make one receptor, the authors explain. In the laboratory, it has been easier to study simpler, more homogenous, but also more artificial constructs. Hansen and his colleagues developed a way to build replicas of the more complicated NMDA receptors found in the brain and probe their distinct responses to drugs. Read more

Posted on by Quinn Eastman in Neuro Leave a comment

Media’s contribution to stigma

Photo credit: Julia Freeman-Woolpert

Tireless advocacy in the last decade by mental health professionals and people who are affected by mental illness has aimed to reduce the stigma of psychiatric disorders. To determine the influence those efforts have had on news media portrayals, Emory researchers studied newspaper articles using the terms “schizophrenia” and “schizophrenic” in the years 2000 versus 2010.

“The primary goal of journalists is to give fair, accurate and unbiased reports of news events that will be of interest to the public,” says study author Arshya Vahabzadeh, MD, resident psychiatrist in the Department of Psychiatry and Behavioral Sciences at Emory University School of Medicine.

Arshya Vahabzadeh, MD, resident psychiatrist in the Department of Psychiatry and Behavioral Sciences at Emory University School of Medicine says that people who suffer from a mental illness often internalize negative references, and develop coping mechanisms that become obstacles to treatment.

“A secondary goal is to capture the attention of readers and viewers,” he says. “Unfortunately, stories linked to a mental illness have been shown to strongly attract readers’ attention, and to contribute to unfavorable public conceptions of mental illness.”

According to the researchers, the decade from 2000 to 2010 was of particular importance to the study because as the new millennium began, attention increasingly focused on public awareness of mental illness, with mental health professionals, advocacy groups and governmental bodies targeting de-stigmatization of psychiatric disorders.

Vahabzadeh and his colleagues examined hundreds of articles that appeared in five major newspapers during a five-month time period during 2000 and 2010, searching for the terms “schizophrenia” and “schizophrenic”.

The researchers found that during that period in 2000, 7,114 articles were published in the five selected newspapers, 247 of which mentioned schizophrenia. During the same period in 2010, 4,397 articles were published, with 151 articles mentioning schizophrenia.

Although a larger percentage of the articles were published in 2000 than in 2010, the percentage of articles mentioning schizophrenia did not differ. Similarly, there was no significant difference in metaphorical usage of the term “schizophrenia” – using the term to describe conflicting decisions or illogical actions.

Of particular concern to investigators was that 60 percent of the human-interest stories in both time periods focused on highly emotive reports of violence, dangerousness and criminality. Murders committed by people with schizophrenia accounted for almost half of such articles. The authors did, however, recognize a smaller proportion of articles focusing on crimes and murder committed by people with schizophrenia in 2010 compared to 2000.

Additionally, despite the fact that people with schizophrenia are more prone to be the victims rather than perpetrators of crime, situations in which people with schizophrenia were reported as victims accounted for only 0.5% of the articles reviewed.

“People who suffer from a mental illness often internalize these negative references, and develop coping mechanisms that become obstacles to treatment,” explains Vahabzadeh.

“Negative perceptions also may result in problems for those who are successfully treated,” he says. “People with schizophrenia may encounter stigma when they attempt to integrate into society, build relationships, find employment and even housing. It is important for us as mental health professionals to look for opportunities to educate the media on ways to become a positive force to reduce stigma.”

Nadine Kaslow, PhD, professor and chief psychologist at the Emory University School of Medicine, whose mentorship inspired the study, says “This study provides invaluable information about the persistence of negative and unfounded portrayals of people living with schizophrenia to the public. It is imperative that everyone interacts with people living with mental illness respectfully and with compassion, and that they be welcomed members of our community.”

The study was published in the Journal of Psychiatric Practice http://www.ncbi.nlm.nih.gov/pubmed/22108403.

Additional study investigators include Justine Wittenauer, MD, Emory University School of Medicine and Erika Carr, PhD, Yale University School of Medicine.

Posted on by Kathi Baker in Uncategorized Leave a comment

Quirky little prairie voles hold answers

Larry Young, PhD

So says Larry Young, PhD, chief of the Division of Behavioral Neuroscience and Psychiatric Disorders at the Yerkes National Primate Research Center, Emory University.

Young, who is world-renowned for his work on the role of neuropeptides in regulating social behavior, uses voles to investigate the neurobiological and genetic mechanisms underlying social behavior. Using the monogamous prairie vole (vs. the promiscuous meadow vole) as a model organism, Young and his research team identified the oxytocin and vasopressin receptors as key mediators of social bonding and attachment. In addition, they are examining the consequences of social bond disruption as a model of social loss-induced depression.

This work has important implications for developing novel treatment strategies for psychiatric disorders associated with social cognitive deficits, including autism spectrum disorders and schizophrenia.

Read more

Posted on by Holly Korschun in Neuro Leave a comment

A shift in how geneticists study complex diseases

An Emory project studying schizophrenia genetics is a good example of how geneticists are shifting from examining small, common mutations to “rare variants” when studying complex diseases.

From studies of twins, doctors have known for a long time that heredity plays a big role in causing schizophrenia. But dissecting out which genes are the most important has been a challenge.

Three landmark studies on schizophrenia genetics published this summer illustrate the limitations of “genome wide association” studies. New York Times science reporter Nicholas Wade summarized the results in this way:

“The principal news from the three studies is that schizophrenia is caused by a very large number of errant genes, not a manageable and meaningful handful.”

The limitations from this type of study comes from the type of markers geneticists are looking at, says Steve Warren, chair of the human genetics department at Emory.

Genome wide association studies usually follow SNPs — single nucleotide polymorphisms. This is a one-letter change somewhere in the genetic code that is found in a fraction of the population. It’s not a big change in the genome, and in many cases, it will have a small effect on disease risk.

Researchers looking for the genes behind complex diseases such as schizophrenia and autism are starting to shift their efforts away from genome wide association studies, Warren says.

Think of a SNP like a misspelling of a word in a certain place in a book, he says. In contrast, the “rare variants” geneticists are starting to study more intensively are more like printers’ errors or missing pages. The rapid sequencing technology that allows scientists to investigate these changes easily is just now coming on line, he says.

One example of these rare variants is DiGeorge syndrome, a deletion that gets rid of dozens of genes on one copy of chromosome 22. Children who have this chromosomal alteration often have anatomical changes to their heart and palate. But it also substantially increases the risk of schizophrenia – to about 25% lifetime risk. That’s a lot more than any of the SNPs identified this summer.

Working with several Emory colleagues, researcher Brad Pearce is planning to examine the genes missing in DiGeorge syndrome in several groups of patients: people with DiGeorge, patients with “typical” schizophrenia and people at high risk of developing schizophrenia.

An article in this spring’s Emory Health describes genetic research on autism. Several of the researchers mentioned there, such as geneticist Joe Cubells and psychiatrist Opal Ousley, are involved in this schizophrenia project as well, because deletions on chromosome 22 also lead to an increased risk of autism.

Pearce’s project is funded through American Recovery and Reinvestment Act money from the NIH.

Posted on by Quinn Eastman in Uncategorized Leave a comment