Featured Research

from universities, journals, and other organizations

Possible Markers For Mental Illness Discovered

Date:
December 5, 2007
Source:
Ohio State University
Summary:
Researchers have discovered natural genetic differences that might help predict the most effective antipsychotic drugs for particular patients with mental disorders such as schizophrenia, Parkinson's and drug addiction. They found the differences in the gene for a molecule called the dopamine D2 receptor, a protein present on brain cells that are sensitive to the neurotransmitter dopamine.

Researchers have discovered natural genetic differences that might help predict the most effective antipsychotic drugs for particular patients with mental disorders such as schizophrenia, Parkinson's and drug addiction.

Related Articles


They found the differences in the gene for a molecule called the dopamine D2 receptor (DRD2), a protein present on brain cells that are sensitive to the neurotransmitter dopamine.

The receptor is known to play a key role in memory and in a variety of mental illnesses. Most antipsychotic drugs work at least in part by blocking this protein, but scientists don't yet understand how this helps patients. Nor can they explain why some people respond well to certain antipsychotic drugs and others respond poorly.

"Our study shows that these differences affect normal brain activity and memory processing, and therefore may also be important in mental illness," says principal investigator Wolfgang Sadee, program director in pharmacogenomics at the Ohio State University Medical Center.

The findings could lead to tests that will enable doctors to match patients with certain mental illnesses to the most effective therapy, something they cannot do now.

The study was done in collaboration with Professor Alessandro Bertolino, University of Bari, Italy, who performed the clinical research. It is published online in the Proceedings of the National Academy of Sciences.

"Identifying these predictive markers is important because antipsychotic drugs are effective in only a portion of patients upon first treatment, and it takes a month or more to establish their efficacy," says Sadee, who is also a professor of psychiatry and chair of the department of pharmacology.

"During this time, irreparable damage can result if the wrong antipsychotic is given to a patient."

Sadee notes that the D2 receptor gene has been implicated in mental illness for some time, but that a variety of clinical studies have failed to consistently link variations in the gene to disease.

These findings may change that.

For this study, Sadee and his colleagues analyzed 68 autopsy samples of normal human brain tissue. For each case, the researchers measured and compared the amount of messenger RNA made by each of the two copies of the DRD2 gene. Messenger RNA is a molecule made when a gene is involved in making its protein.

In 15 of the 68 cases, the relative amounts of messenger RNA made by one gene in the pair was strikingly different from the amount made by the other. The disparity was a clue that something was different between the genes.

Comparisons of these DRD2 genes to the rest revealed three small differences in the DNA called single-nucleotide polymorphisms, or SNPs (pronounced 'snips').

SNPs are tiny natural variations between individuals that occur at certain positions in genes, providing landmarks in the genome.

SNPs often have no effect on the function of the gene or its protein, but, in this case, laboratory experiments showed that particular changes in two of the SNPs alters how the messenger RNA for DRD2 is processed.

That, in turn, changed the relative amounts of two variants of the protein that are made by the gene.

"The two variants of DRD2 have distinct functions, facilitating or inhibiting dopaminergic transmission, so that a change in their ratios is potentially critical," Sadee says. "We believed that this change would enhance dopamine activity in the brain."

The researchers then tested this hypothesis in normal human volunteers who took simple memory performance tests. The participants' brain activity was monitored during the testing by functional magnetic resonance imaging (fMRI).

The results showed that volunteers with the two variant SNPs had significantly more brain activity than the usual SNPs for the same memory task.

"Their brain needed to 'work' more to get the same result," Sadee says. The two SNPs were also associated with reduced memory performance and attentional control.

Sadee and his colleagues are now testing the relevance of the SNP markers in patients with schizophrenia and in patients with cocaine addiction.

Funding from the National Institute on Drug Abuse supported this research.


Story Source:

The above story is based on materials provided by Ohio State University. Note: Materials may be edited for content and length.


Cite This Page:

Ohio State University. "Possible Markers For Mental Illness Discovered." ScienceDaily. ScienceDaily, 5 December 2007. <www.sciencedaily.com/releases/2007/12/071203190604.htm>.
Ohio State University. (2007, December 5). Possible Markers For Mental Illness Discovered. ScienceDaily. Retrieved February 1, 2015 from www.sciencedaily.com/releases/2007/12/071203190604.htm
Ohio State University. "Possible Markers For Mental Illness Discovered." ScienceDaily. www.sciencedaily.com/releases/2007/12/071203190604.htm (accessed February 1, 2015).

Share This


More From ScienceDaily



More Health & Medicine News

Sunday, February 1, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Hikers Rescued After Fall from Oregon Mountain

Hikers Rescued After Fall from Oregon Mountain

AP (Feb. 1, 2015) Two climbers who were hurt in a fall on Mount Hood are now being treated for their injuries. Rescue officials say they were airlifted off the mountain Saturday afternoon by an Oregon National Guard helicopter. (Feb. 2) Video provided by AP
Powered by NewsLook.com
Smart Glasses Augment Reality to Help Visually Impaired

Smart Glasses Augment Reality to Help Visually Impaired

Reuters - Innovations Video Online (Feb. 1, 2015) New augmented reality smart glasses developed by researchers at Oxford University can help people with visual impairments improve their vision by providing depth-based feedback, allowing users to "see" better. Joel Flynn reports. Video provided by Reuters
Powered by NewsLook.com
Flu Season Hitting Elderly Hard

Flu Season Hitting Elderly Hard

Reuters - US Online Video (Jan. 31, 2015) The CDC says this year&apos;s flu season is hitting people 65 years of age and older especially hard. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
CDC: Get Vaccinated for Measles

CDC: Get Vaccinated for Measles

Reuters - US Online Video (Jan. 30, 2015) The CDC is urging people to get vaccinated for measles amid an outbreak that began at Disneyland and has now infected more than 90 people. Linda So reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins