Research suggests shared genetic link in psychiatric and movement disorders

(Press-News.org) WINSTON-SALEM, N.C. – Sept., 26, 2012 – Fewer than 100 people in the world are known to be affected by a movement disorder called rapid-onset dystonia-parkinsonism (RDP), but its symptoms are life-changing. Seemingly normal young people are suddenly and dramatically unable to control movement of their arms or legs and have trouble speaking or swallowing. A normal life is nearly impossible.

RDP is caused by a genetic mutation (ATP1A3) that often runs in families. Now Wake Forest Baptist Medical Center researchers believe that same genetic predisposition might also be associated with psychiatric problems, such as anxiety, mood disorders and substance abuse/dependence.

Allison Brashear, M.D., chair of neurology at Wake Forest Baptist, and the lead investigator in this $2.5 million, four-year study funded by the National Institute of Neurological Disorders and Stroke (NINDS), said this is one of the few studies to look at this rare condition that has no known treatment. "RDP often occurs suddenly after a stressful episode, such as running a marathon or childbirth," said Brashear. "Patients become severely disabled over hours to days and do not recover."

Brashear and nine other Wake Forest Baptist scientists, as well as colleagues from Harvard Medical School and Mount Sinai School of Medicine, enrolled 56 individuals for this study. Twenty-three of the RDP patients were related, three RDP patients were unrelated. Of the 29 participants with the genetic mutation, 26 had dystonia symptoms and three were carriers, but without the motor symptoms; the remaining 27 participants without the mutation, were enrolled as the control group.

Following standard physical examination and behavioral assessment, Brashear's team found that individuals with the mutation but without the motor symptoms did not report any history of psychiatric disorder, while those with dystonia symptoms reported anxiety (48 percent; control 41percent), mood (50 percent; control 22 percent), psychotic (19 percent; control 0 percent) and substance abuse/dependence (38 percent; control 27 percent).

Researchers concluded that ATP1A3 mutations cause a wide spectrum of motor and nonmotor symptoms and that psychotic symptoms tended to develop before or simultaneous to the beginning of motor dysfunction. Further, the team believes the findings suggest psychiatric disorders may be another expression of the genetic mutation. Brashear said there are also clinical implications as a result of this study and suggested that those who deal with patients with psychosis, particularly in families with a history of dystonia-parkinsonism, consider the genetic mutation as a possible contributor to the mental illness.

### Co-authors in this study were: Jared F. Cook, M.A., Deborah F. Hill, M.A, Alethea Amponsah, B.A., Beverly M. Snively, Ph.D., Laney Light, M.S., Cynthia K. Suerken, M.S., W. Vaughn McCall, M.D., and Niki Boggs, B.A., of Wake Forest Baptist; Laurie Ozelius, Ph.D., Mount Sinai School of Medicine; and Kathleen J. Sweadner, Ph.D., Harvard Medical School.

Funding for this study was provided by the National Institute for Neurological Disorders and Stroke through Grant # NINDS 5R01-NS058949-04.