Marijuana from Colorado is flowing into neighboring states, according to law enforcement officials. In those states, drug arrests in counties near the Colorado border are on the rise, the Los Angeles Times reports.

"It has just devastated these smaller agencies," said Tom Gorman, Director of the Rocky Mountain High Intensity Drug Trafficking Area program, which includes law enforcement organizations in four Western states. "The marijuana laws [in Colorado] were supposed to eliminate the black market. But in effect they have become the black market."

Possession of small amounts of marijuana is legal for adults in Colorado, but it remains illegal to take the drug out of state.

Rural counties along Nebraska's panhandle have been especially hard hit.

Law enforcement officials in Thomas County, Kansas and San Juan County, New Mexico also report an increase in marijuana coming from Colorado. Marc Finley, undersheriff for Thomas County, said the number of marijuana-impaired driving arrests recently surpassed those involving alcohol in his area.

Government researchers will have access to an increased supply of marijuana for medical research, the Drug Enforcement Administration (DEA) has announced.

Researchers at the National Institute on Drug Abuse (NIDA) will now have access to 650 kilograms of marijuana, up from 21 kilograms, The Hill reports. The marijuana is grown at facilities at the University of Mississippi.

NIDA has conducted about 30 studies on marijuana, according to the article. It also funds private research on the drug. "The additional supply to be manufactured in 2014 is designed to meet the current and anticipated research efforts involving marijuana - this projection of increased demand is due in part to the recent increased interest in the possible therapeutic uses of marijuana," NIDA said in a statement to The Hill.

NBC News reports NIDA will increase testing on the effects of marijuana on treatment of many conditions, including cancer, inflammation, pain, seizures, psychiatric disorders and autoimmune diseases.

Young people who misuse prescription stimulants to increase their attention span and memory may be risking long-term impairment to brain function, a new study suggests.

Researchers reviewed studies on potential lasting side effects of misusing "study drugs" such as Ritalin or Provigil. They found any short-term boosts in mental performance were offset by long-term decrease in brain plasticity, needed for planning ahead, switching between tasks and being flexible in behavior.

One of the drugs studied was methylphenidate, sold under the brand names Ritalin and Concerta. The drug is prescribed to treat attention deficit hyperactivity disorder. The researchers also looked at modafinil (Provigil), used to treat sleep disorders such as narcolepsy, Time reports. In addition, they surveyed the research on an emerging class of drugs called ampakines, being studied by the U.S. military to see if it will increase alertness in soldiers.

"What's safe for adults is not necessarily safe for kids," lead researcher Kimberly Urban of the University of Delaware said in a news release. "The human brain continues to develop until our late twenties or early thirties. Young people are especially prone to abuse smart drugs, but also more vulnerable to any side-effects. We simply don't know enough about the long-term effects of these drugs on the developing brain to conclude they are safe."

The findings are published in Frontiers in Systems Neuroscience.