HCPLive Network

How Gene Variant Linked to ADHD Could Operate

ADHD and other disorders characterized by decreased impulse control, including drug abuse, have been linked to dysfunction of the dopamine D4 receptor subtype. One subtype variant, D4.7, has been of particular interest because of its increased prevalence in those diagnosed with attention deficit-hyperactivity disorder (ADHD), but its function in ADHD has been poorly understood.

However, a mouse study published recently in Molecular Psychiatry provides insight into how D4.7 could play a role in increasing a person’s risk for ADHD and could also help explain how stimulants work to treat symptoms of ADHD.

Researchers inserted three variants of the dopamine D4 receptor into cells and into mice to investigate differences in biological activities. The researchers found that the D4.7 variant, unlike its D4.2 and D4.4 counterparts, was unable to interact with the short version of the dopamine type 2 (D2S) receptor to reduce glutamate release in a brain region associated with impulsivity and symptoms of ADHD in humans.

“Although previous studies have shown that dysfunctional dopamine D4 receptors are implicated in ADHD, this is the first study to show how this genetic difference might translate into functional deficits seen with this disorder,” Nora D. Volkow, MD, said in a press release. “Further research is needed to explore how this deficient interaction between receptors might be remedied, which could then lead to new medications for the treatment of ADHD,” added Volkow, who is director of the National Institute on Drug Abuse.

Although psychostimulant medications, which are the most commonly used treatment for ADHD, alleviate some symptoms, it is unclear how these compounds act within the brain to do so.

“Our results suggest that psychostimulants might reduce glutamate release by amplifying this D4/D2S interaction,” said Sergi Ferre, MD, the study’s primary author, said in a press release. “These results might also explain why these medications are less efficient in patients with the D4.7 variant.”

Source
Scientists Show How Gene Variant Linked to ADHD Could Operate [Molecular Psychiatry]



Further Reading
The FDA has approved Baxter’s Rixubis [Coagulation Factor IX (Recombinant)], an intravenous prophylactic treatment intended to control and prevent bleeding episodes and assist with perioperative management for children 12 years and younger with hemophilia B.
A compound known as P7C3-S243 appears to keep axons from degenerating after a blast injury, a University of Iowa mouse study has found. “We propose that P7C3-S243 serves as a chemical scaffold upon which new drugs can be designed to treat patients with condition of axonal degradation such as occurs in traumatic brain injury or other neurodegenerative disease,” the researchers wrote
Researchers have long known that the risk for schizophrenia is inherited. In new findings published online Sept 15 in The American Journal of Psychiatry, senior investigator C. Robert Cloninger, MD, PhD, of the Washington University School of Medicine in St. Louis, MO, said his team identified distinct gene clusters that contribute to 8 different classes of the disease.
Nancy Chiaravalloti, PhD, shares how cognitive function impacts patients with progressive multiple sclerosis at the 2014 Joint ACTRIMS-ECTRIMS Meeting in Boston.
A new set of guidelines from the American College of Physicians (ACP) advises physicians to prescribe exercises and behavioral therapy—not drugs—as first-line treatment for many patients with urinary incontinence (UI).
Using an experimental and highly sensitive test for cardiac troponin, a team of Johns Hopkins researchers found undetected signs of heart muscle damage in people with diabetes and pre-diabetes. That may suggest that hypoglycemia directly damages the heart.
As reported in the EMBO Molecular Medicine journal, researchers have discovered there are several types of dendritic cells within human skin that play a role in both the earlier and more advances stages of psoriasis.
More Reading