December 15, 2011

NDAR Federation Creates Largest Source of Autism Research Data to Date


NIH-funded Database Sets Standard for Collaboration and Data Sharing

Source: NDAR

A data partnership between the National Database for Autism Research (NDAR), and the Autism Genetic Resource Exchange (AGRE) positions NDAR as possibly the largest repository to date of genetic, phenotypic, clinical, and medical imaging data related to research on autism spectrum disorders (ASD)LPC Continuing Education

“The collaboration between AGRE and NDAR exemplifies the efforts of government and stakeholders to work together for a common cause,” said Thomas R. Insel, M.D., director of the National Institute of Mental Health, part of NIH. “NDAR continues to be a leader in the effort to standardize and share ASD data with the research community, and serves as a model to all research communities.”

NDAR is supported by the National Institutes of Health; AGRE is an Autism Speaks program.

NDAR’s mission is to facilitate data sharing and scientific collaboration on a broad scale, providing a shared common platform for autism researchers to accelerate scientific discovery. Built around the concept of federated repositories, NDAR integrates and standardizes data, tools, and computational techniques across multiple public and private autism databases. Through NDAR, researchers can access results from these different sources at the same time, using the rich data set to conduct independent analyses, supplement their own research data, or evaluate the data supporting published journal articles, among many other uses.

Databases previously federated with NDAR include Autism Speaks’ Autism Tissue Program, the Kennedy Krieger Institute’s Interactive Autism Network (IAN), and the NIH Pediatric MRI Data Repository. AGRE currently houses a clinical dataset with detailed medical, developmental, morphological, demographic, and behavioral information from people with ASD and their families.

Approved NDAR users will have access to data from the 25,000 research participants represented in NDAR, as well as 2,500 AGRE families and more than 7,500 participants who reported their own information to IAN.

NDAR is supported by NIMH, the Eunice Kennedy Shriver National Institute of Child Health and Human Development, the National Institute of Neurological Disorders and Stroke, the National Institute of Environmental Health Sciences, and the NIH Center for Information Technology.

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The mission of the NIMH is to transform the understanding and treatment of mental illnesses through basic and clinical research, paving the way for prevention, recovery and cure. For more information, visit the NIMH website.

About the National Institutes of Health (NIH): NIH, the nation's medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit the NIH website.

December 06, 2011

Suspect Gene Variants Boost PTSD Risk after Mass Shooting

Profile of Risk Emerging for Trauma-triggered Molecular Scars

College students exposed to a mass shooting were 20-30 percent more likely to later develop post traumatic stress disorder (PTSD) symptoms if they harbored a risk version of a gene, NIMH-funded researchers have discovered. This boost in risk, traced to common variants of the gene that controls recycling of serotonin, was comparable to the risk conferred by close proximity to the shooting – for example, being in the room with the shooter versus just being on campus.

The discovery is the latest of several recently reported that collectively profile heightened biological vulnerability to developing PTSD following trauma – and the molecular scars it leaves in the brain.

For example, early this year, researchers linked high levels of a stress-triggered, estrogen-related hormone to PTSD symptoms in women, with certain versions of the hormone receptor’s gene conferring higher risk. A PET scan study in September traced increased PTSD symptoms to heightened levels of a serotonin receptor. Both studies suggest potential new drug targets for treating the disorder. Evidence is also mounting that trauma – particularly if experienced very early in life – can adversely alter the set-points of gene expression in brain stress circuits and compromise immune and inflammatory system function continuing education for counselors

Gene-by-environment – caught in the act

By chance, researchers at Northern Illinois University (NIU) had already collected data on students’ PTSD symptoms prior to the 2008 murder-suicide that killed six on the Dekalb, Illinois campus.*

“This provided a rare opportunity to pinpoint not just a correlation but a cause – to document that such a tragedy can conspire with a risk gene to produce the disorder,” explained Kerry Ressler, M.D., Ph.D., of Emory University.

NIMH grantees Ressler, NIU’s Holly Orcutt, Ph.D., and colleagues, report on discovery of this gene-by-environment interaction online September 5th 2011 in the Archives of General Psychiatry.

Previous efforts to confirm such an interaction in PTSD had been confounded by lack of data on individuals’ pre-trauma symptoms. Any pre-existing symptoms must be taken into account to establish a common baseline – so that new symptoms that develop can confidently be pegged to the traumatic event.

By chance, before the tragedy, Orcutt’s team had prospectively surveyed PTSD symptoms in more than a thousand NIU undergraduate women, as part of a longitudinal study on predictors of sexual victimization, which can trigger the disorder. Within a few weeks after the tragedy, they seized the opportunity and – with help from a NIMH RAPID grant – conducted follow-up surveys, using the same measures, in subsets of the original sample – and then again after several months – to track symptom changes. Ressler’s team ultimately analyzed saliva samples from 235 women for gene type.

Previous studies had linked PTSD to a version of the gene that codes for the serotonin transporter (SERT), the protein on neurons that recycles the chemical messenger serotonin back into the cell after it is secreted into the synapse. So the researchers focused their genetic analysis on this variation, noting that it is “the most commonly described polymorphism in the psychiatric genetics literature.”

For example, this same site of genetic variation has also been linked to increased risk for anxiety - and, in some studies, increased risk for depression following stressful life events, although the latter findings remain controversial. Some hypothesize that these implicated variants may have less to do with conferring disease risk, per se, than with increased sensitivity to environmental influences more generally.**

Antidepressant medications, serotonin selective reuptake inhibitors (SSRIs), work by blocking SERT, thereby enhancing serotonin activity. SSRIs are the main medication treatment for PTSD.

Everyone inherits two copies of the SERT gene, one from each parent. So people can inherit one or two copies of risk-associated versions that are common in the population. Carrying any combination of these risk versions had been associated with increased risk for PTSD in 8 out of 9 previous studies.

The new study more definitively connects the dots between the environmental trigger and these risk gene types. Among 204 women without prior symptoms, 20 percent of those who showed acute symptoms within a few weeks after the shooting had developed PTSD symptoms when surveyed several months later. Proximity to the shooting and the risk gene types were about equally predictive of increased risk among this group.

These results come at a time of ferment in the field over confidence in gene-by-environment findings. A recent analysis by NIMH grantees of more than 100 such studies over the past decade uncovered what they call “publication bias.” They found that positive new findings were more likely to get published, while direct replications – which tend be less likely to confirm positive new findings – were under-reported. The net effect: an unintentional bias toward false positive reports. Notably, the researchers singled out as a prime example of this bias the scientific literature on serotonin transporter gene-by-environment interactions.

“How we measure environment may be at least as important as how we measure genetics, but to date, little effort has been focused on that,” noted Ressler. “We think that performing prospective studies in populations with shared trauma may be one way to 'hold constant' the environment variable, thus allowing for more clarity in the role of genetics.”



PTSD symptoms of NIU undergraduate women with a risk-associated serotonin transporter gene type (s/s, lG/lG, s/lG) increased 20-30 percent more than in classmates with a protective gene type after the 2008 campus shootings (Time 2). The increased risk was comparable to that conferred by close proximity to the shooting.
Source: Kerry Ressler, M.D., Ph.D., Emory University

Why Women are More Vulnerable

Earlier this year, Ressler and colleagues reported findings that may help to explain why women are twice as likely as men to develop PTSD. They linked PTSD symptoms in women to higher blood levels of what has been dubbed the “master regulator” of the stress response, a hormone called PACAP (pituitary adenyl cyclase-activating peptide).

PTSD symptoms were 5-fold higher in women with above average PACAP levels, compared to women with below average levels. Also in women only, a certain version of the gene that codes for PACAP’s receptor, PAC-1, conferred increased vulnerability. Experiments in rodents confirmed that this variable part of the PAC-1 gene is regulated, in part, by the female hormone estrogen.

This suggests that heightened vulnerability to PTSD in females may be traceable to this brain system critical to proper stress circuit function. Genetic variation in a different pathway may similarly be linked to increased risk for PTSD in men, say the researchers.



Females with higher-than-average levels of the stress-managing hormone PACAP had 5 times more PTSD symptoms than females with lower-than-average levels. By contrast, PACAP levels were unrelated to PTSD symptoms in males. Since the PACAP system is shaped, in part, by the female hormone estrogen, these differences could help to explain why women are twice as likely as men to develop the disorder.
Source: Kerry Ressler, M.D., Ph.D., Emory University



PACAP, “master regulator” of the stress response.
Source: Lee Eiden, Ph.D., NIMH Section on Molecular Neuroscience

Molecular scars

The Emory researchers also found increased methylation – epigenetic regulation of gene expression in response to the environment – in the part of Pac1 associated with PTSD in both women and men. Adverse experiences can induce molecules called methyl groups to attach to DNA and block genes from turning on. This results in enduring changes in the proteins the genes express. These molecular scars can weaken the brain’s defenses against PTSD.

Indeed, methylation increases pervasively in PTSD, according to Ressler and colleagues. Notably, they pinpointed such increases in several genes implicated in inflammatory and immune system abnormalities that go along with PTSD. They also saw abnormalities in immune system chemical messengers, called cytokines. Increased blood levels of one such cytokine TNF-alpha, known to trigger stress response symptoms, correlated with a history of child abuse and cumulative life stresses.

Early trauma may deplete resilience molecule

In September, a NIMH-funded brain imaging study reported that levels of a type of serotonin receptor (1B) were markedly lower in stress circuits of PTSD patients than in others exposed to trauma. This protein on neurons, to which the neurotransmitter binds, plays a pivotal role in stress resilience and antidepressant effect. By contrast, PET scans revealed that people who had experienced trauma but didn’t develop PTSD had only slightly fewer receptors than healthy controls.

NIMH grantee Alexander Neumeister, M.D., of Mount Sinai School of Medicine, and colleagues, traced both the severity of symptoms and the depleted receptors largely to the age at which trauma was first experienced. The earlier the age and the more subsequent trauma exposures, the fewer receptors expressed and the more severe the PTSD symptoms and overlap with depression. The dearth of receptors likely reflects such features of patients’ trauma histories, with those who develop PTSD also having other genetic or environmental vulnerabilities, say the researchers.



Patients with PTSD (right) had significantly fewer serotonin 1B receptors (yellow & red areas) in their brain stress circuits than healthy controls (left). PET scan images show destinations of a radioactive tracer that binds to serotonin 1B receptors. Front of brain is at bottom.
Source: Alexander Neumeister, M.D., Mount Sinai School of Medicine

Possible Uses: Risk profile and treatment targets?

Such epigenetic and genetic signatures of PTSD proneness in blood and brain, together with behavioral measures, may collectively prove useful in profiling a patient’s risk for developing the disorder. Molecules such as PACAP and the serotonin 1B receptor may also hold promise as potential targets of new drugs aimed at correcting specific abnormalities in the affected brain pathways, suggest the researchers.


NIMH RAPID grant helps salvage science from tragedy
2/14/08 Mass shooting on NIU campus
2/19/08 NIU researcher Holly Orcutt, Ph.D., contacts NIMH to discuss how to make the most of her prospectively collected data on PTSD and other parameters to learn from the tragedy.
3/26/08 Orcutt submits a concept for a follow-up study under the NIMH Rapid Assessment Post Impact of Disaster (RAPID) research program announcement – a unique time sensitive mechanism for expediting funding of research grants in response to emergency situations.
5/17/08 Grant application submitted.
6/18/08 Application undergoes peer review.
9/18/08 Grant awarded to NIU and Orcutt.

References

Acute and Posttraumatic Stress Symptoms in a Prospective Gene x Environment Study of a University Campus Shooting. Mercer KB, Orcutt HK, Quinn JF, Fitzgerald CA, Conneely KN, Barfield RT, Gillespie CF, Ressler KJ. Arch Gen Psychiatry. 2011 Sep 5. [Epub ahead of print]
PMID:21893641

A Critical Review of the First 10 Years of Candidate Gene-by-Environment Interaction Research in Psychiatry. Duncan LE, Keller MC. Am J Psychiatry. 2011 Sep 2. [Epub ahead of print]
PMID: 21890791

Post-traumatic stress disorder is associated with PACAP and the PAC1 receptor.
Ressler KJ, Mercer KB, Bradley B, Jovanovic T, Mahan A, Kerley K, Norrholm SD, Kilaru V, Smith AK, Myers AJ, Ramirez M, Engel A, Hammack SE, Toufexis D, Braas KM, Binder EB, May V.Nature. 2011 Feb 24;470(7335):492-7. Erratum in: Nature. 2011 Sep 1;477(7362):120.
PMID:21350482

PACAP: a master regulator of neuroendocrine stress circuits and the cellular stress response.
Stroth N, Holighaus Y, Ait-Ali D, Eiden LE. Ann N Y Acad Sci. 2011 Mar;1220:49-59. doi: 10.1111/j.1749-6632.2011.05904.x. Review. PMID:21388403

The Effect of Early Trauma Exposure on Serotonin Type 1B Receptor Expression Revealed by Reduced Selective Radioligand Binding. Murrough JW, Czermak C, Henry S, Nabulsi N, Gallezot JD, Gueorguieva R, Planeta-Wilson B, Krystal JH, Neumaier JF, Huang Y, Ding YS, Carson RE, Neumeister A. Arch Gen Psychiatry. 2011 Sep;68(9):892-900. PMID:21893657

Differential immune system DNA methylation and cytokine regulation in post-traumatic stress disorder. Smith AK, Conneely KN, Kilaru V, Mercer KB, Weiss TE, Bradley B, Tang Y, Gillespie CF, Cubells JF, Ressler KJ. Am J Med Genet B Neuropsychiatr Genet. 2011 Sep;156(6):700-8. doi: 10.1002/ajmg.b.31212. Epub 2011 Jun 28. PMID:21714072

Psychiatry: A molecular shield from trauma. Stein MB. Nature. 2011 Feb 24;470(7335):468-9. No abstract available. PMID:21350472

*http://en.wikipedia.org/wiki/Northern_Illinois_University_shooting

** http://www.theatlantic.com/magazine/archive/2009/12/the-science-of-success/7761/

December 01, 2011

HIV Variants in Spinal Fluid May Hold Clues in Development of HIV-related Dementia


NIMH-funded researchers found two variants of HIV in the cerebrospinal fluid (CSF) of infected study participants that were genetically distinct from the viral variants found in the participants’ blood. The study, published October 6, 2011, in the journal PLoS Pathogens, suggests these CSF variants may help to inform research on the development and treatment of cognitive problems related to HIV infection.

Background

The advent of antiretroviral medications has helped many with HIV to manage the illness effectively. But even with proper treatment, a significant percentage of HIV-infected people develop HIV-associated dementia (HAD) or more mild neurological disorders. Research suggests that some people with HAD harbor variants of HIV in their cerebrospinal fluid (CSF) that may be less responsive to current treatments and thus contribute to cognitive decline. Understanding the role of HIV in HAD may also inform efforts to treat or prevent mild neurocognitive disorders associated with HIV.

To explore this issue, Ronald Swanstrom, Ph.D., of the University of North Carolina at Chapel Hill, and colleagues collected samples of blood and CSF from 11 people with HIV. All samples were collected just before and shortly after the person started antiretroviral therapy. The researchers also had access to additional samples from two of the 11 participants, collected several years prior to their starting treatment ceus for counselors

Results of the Study

The researchers found two variants of HIV in participants’ CSF that were genetically distinct from HIV found in their blood. Among participants diagnosed with HAD, the HIV variants in CSF showed greater genetic differences from the type of HIV in their blood, compared with participants with no HAD symptoms.

HIV typically targets a type of immune cell called T-cells. However, researchers found that one CSF variant replicated in macrophages, a different type of immune cell that typically lives longer than T-cells. In one of the participants with longer-term data, the researchers found evidence of this variant before the participant was diagnosed with HAD. During that time, the participant’s neurological assessments reported only mild impairment. The proportion of macrophage-targeting variants in the CSF increased over time, particularly in the first month after the participant was diagnosed with HAD.

In the other participant with longer-term data, the researchers noted the presence of the second CSF variant, which targeted T-cells, after the participant was diagnosed with HAD. Before the participant was diagnosed with HAD, the T-cell-targeting variant was not present in CSF samples.

Significance

The findings indicate that the genetically distinct variants of HIV in the CSF may each play a role in the development of HAD and related neurological disorders.

According to the researchers, the variant that targets macrophages provides clues to how HIV may evolve in order to replicate in a new cell type. The presence of the T-cell-targeting variant suggests that HIV infection may cause T-cells to migrate into the CSF. If confirmed, this migration would provide an alternative mechanism for maintaining viral replication in the central nervous system, which is associated with neurocognitive impairment.

What’s Next

Examining samples of blood, CSF, and brain tissue from a larger number of HIV- infected people with more mild symptoms of neurocognitive impairment may reveal physiological features that distinguish the two CSF variants identified in the current study. According to the researchers, identifying such features may help predict either current or future neurocognitive impairment and would emphasize the benefits of starting treatment early.

Reference

Schnell G, Joseph S, Spudich S, Price RW, Swanstrom. HIV-1 Replication in the Central nervous System Occurs in Two Distinct Cell Types. PLoS Pathog. 2011 Oct;7(10):e1002286