WASHINGTON (Reuters) - Young adults who abuse amphetamines may be more likely to suffer an often fatal tear in the body's main artery, the aorta, U.S. researchers said on Tuesday.

A study of medical records from 31 million people aged 18 to 49 and hospitalized from 1995 to 2007 found that those who had abused amphetamines had triple the odds of aortic
dissection, the team at the University of Texas Southwestern Medical
Center said.

Amphetamines, often called speed or crank, are widely abused but also legitimately used to treat attention deficit disorder, narcolepsy and other sleep disorders. They can also
aid in weight loss.

The drugs make the heart beat harder and can raise blood pressure. Researchers have previously found they could raise the risk of heart attack and some had suspected that abusing
the drugs could also cause aortal tears.

Writing in the American Heart Journal, Dr. Arthur Westover and his colleagues at UTSW said they also examined medical records for more than 49 million people over 50 from
the same period.

"We found that the frequency of aortic dissection is increasing in young adults but not older adults," Westover said in a statement. "It is not yet clear why."

"Doctors should screen young adults with aortic dissection for amphetamine abuse in searching for a potential cause."

Records from patients in California, Hawaii, Oregon and Washington state showed three times as many cases of aortic dissection linked to amphetamine abuse among young adults. These
states also have higher than average rates of amphetamine abuse,
Westover said.

"This illustrates that in areas where amphetamine abuse is more common, there are greater public health consequences," he said.

According to the National Institute on Drug Abuse, amphetamine and methamphetamine abuse is worsening in the United States.

In 1992 about 21,000 people were admitted to hospitals for treatment of amphetamine and methamphetamine abuse, representing 1 percent of all treatment admissions during the
year. By 2004, this figure had risen to 150,000, representing 8 percent
of all admissions.

(Reporting by Maggie Fox; Editing by Julie Steenhuysen and Paul Simao)