Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Gene more than doubles risk of depression following life stresses

18.07.2003


Among people who had inherited two copies of the stress-sensitive short version of the serotonin transporter gene (s/s), 43 percent developed depression following four stressful life events in their early twenties, compared to 17 percent among people with two copies of the stress-protective long version (l/l). About 17 percent of the 847 subjects carried two copies of the short version, 31 percent two copies of the long version, and 51 percent one copy of each version. Source: Avshalom Caspi,Ph.D.


Gene more than doubles risk of depression following life stresses

Among people who suffered multiple stressful life events over 5 years, 43 percent with one version of a gene developed depression, compared to only 17 percent with another version of the gene, say researchers funded, in part, by the National Institute of Mental Health (NIMH). Those with the "short," or stress-sensitive version of the serotonin transporter gene were also at higher risk for depression if they had been abused as children. Yet, no matter how many stressful life events they endured, people with the "long," or protective version experienced no more depression than people who were totally spared from stressful life events. The short variant appears to confer vulnerability to stresses, such as loss of a job, breaking-up with a partner, death of a loved one, or a prolonged illness, report Drs. Avshalom Caspi, Terrie Moffitt, University of Wisconsin and King’s College London, and colleagues, in the July 18, 2003 Science.

The serotonin transporter gene codes for the protein in neurons, brain cells, that recycles the chemical messenger after it’s been secreted into the synapse, the gulf between cells. Since the most widely prescribed class of antidepressants act by blocking this transporter protein, the gene has been a prime suspect in mood and anxiety disorders. Yet, its link to depression eluded detection in eight previous studies.



"We found the connection only because we looked at the study members’ stress history," noted Moffitt. She suggested that measuring such pivotal environmental events -- which can include infections and toxins as well as psychosocial traumas – might be the key to unlocking the secrets of psychiatric genetics.

Although the short gene variant appears to predict who will become depressed following life stress about as well as a test for bone mineral density predicts who will get a fractured hip after falling, it’s not yet ready for use as a diagnostic test, Moffitt cautioned. If confirmed, it may eventually be used in conjunction with other, yet-to-be-discovered genes that predispose for depression in a "gene array" test that could help to identify candidates for preventive interventions. Discovering how the "long" variant exerts its apparent protective effect may also lead to new treatments, added Moffitt.

Everyone inherits two copies of the serotonin transporter gene, one from each parent. The two versions are created by a slight variation in the sequence of DNA in a region of the gene that acts like a dimmer switch, controlling the level of the gene’s turning on and off. This normal genetic variation, or polymorphism, leads to transporters that function somewhat differently. The short variant makes less protein, resulting in increased levels of serotonin in the synapse and prolonged binding of the neurotransmitter to receptors on connecting neurons. Its transporter protein may thus be less efficient at stopping unwanted messages, Moffitt suggests.

Moffitt and colleagues followed 847 Caucasian New Zealanders, born in the early l970s, from birth into adulthood. Reflecting the approximate mix of the two gene variants in Caucasian populations, 17 percent carried two copies of the stress-sensitive short version, 31 percent two copies of the protective long version, and 51 percent one copy of each version.

Based on clues from studies in knockout mice, monkeys and functional brain imaging in humans, the researchers hypothesized that the short variant predisposed for depression via a "gene-by-environment interaction." They charted study participants’ stressful life events – employment, financial, housing, health and relationship woes – from ages 21-26. These included debt problems, homelessness, a disabling injury, and being an abuse victim. Thirty percent had none, 25 percent one, 20 percent two, 11 percent three, and 15 percent four or more such stressful life experiences. When evaluated at age 26, 17 percent of the participants had a diagnosis of major depression in the past year and three percent had either attempted or thought about suicide.

Although carriers of the short variant who experienced four or more life stresses represented only 10 percent of the study participants, they accounted for nearly one quarter of the 133 cases of depression. Among those with four or more life stresses, 33 percent with either one or two copies of short variant -- and 43 percent of those with two copies of the short variant – developed depression, compared to 17 percent of those with two copies of the long variant.

The stressful life events led to onset of new depression among people with one or two copies of the short gene variant who didn’t have depression before the events happened. The events failed to predict a diagnosis of new depression among those with two copies of the long variant. Among those who had experienced multiple stressful events, 11 percent with the short variant thought about or attempted suicide, compared to 4 percent with two copies of the long variant. These self-reports were corroborated by reports from participants’ loved ones.

The researchers suggest that effects of genes in complex disorders like psychiatric illnesses are most likely to be uncovered when such life stresses are measured, since a gene’s effects may only be expressed, or turned on, in people exposed to the requisite environmental risks.

Also participating in the study were: Karen Sugden, Alan Taylor, Dr. Ian Craig, Joseph McClay, Jonathan Mill, King’s College London; Dr. Honalee Harrington, University of Wisconsin; Judy Martin, Dr. Richie Poulton, Dunedin School of Medicine; Dr. Antony Braithwaite, University of Otago.

In addition to NIMH, the research was also supported by the University of Wisconsin Graduate School, United Kingdom Medical Research Council, Health Research Council of New Zealand, William T. Grant Foundation, Royal Society-Wolfson Research Merit Award.

NIMH is part of the National Institutes of Health (NIH), the Federal Government’s primary agency for biomedical and behavioral research. NIH is a component of the U.S. Department of Health and Human Services.

Jules Asher | EurekAlert!
Further information:
http://www.nimh.nih.gov

More articles from Health and Medicine:

nachricht Investigators may unlock mystery of how staph cells dodge the body's immune system
22.09.2017 | Cedars-Sinai Medical Center

nachricht Monitoring the heart's mitochondria to predict cardiac arrest?
21.09.2017 | Boston Children's Hospital

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: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>