Recent legislative efforts to either decriminalize or legalize marijuana have led to the perception that smoking a little pot may not be so bad for a person. However, the findings of a recent study from Harvard University researchers shows that the drug can lead to serious cognitive deficits, especially in individuals who begin smoking at a young age.

For the study, researchers asked a group of smokers and nonsmokers to sort a deck of cards based on certain rules. To test participants' mental flexibility, the rules of sorting were changed halfway through.

Researchers found that individuals who habitually smoked marijuana made repeated errors on the test, despite being told over and again that they were wrong. Additionally, individuals who reported starting smoking before age 16 showed the greatest impairment.

The authors of the study noted in their report that their findings provide solid evidence of the damage that smoking marijuana can cause, especially during adolescence when the brain is still forming.

Parents who believe that their children are abusing drugs may want to consider substance abuse programs for youths to help them avoid the long-term cognitive deficits caused by drugs.