Unlike drugs and alcohol, excess Internet usage could help your career, make you more informed and keep you up-to-date with the latest hilarious memes. But a recent (small) study by researchers in China showed that too much Internet usage — to the point that it's an addiction — can cause structural damage to your brain.

The researchers studied 17 adolescents with Internet Addiction Disorder (IAD) and found structural and functional interference in the part of the brain that regulates organization, possibly causing cognitive impairment similar to that caused by gambling and alcoholism.

Here's the science behind it: White matter is composed of nerve cells, while the gray matter that we hear so much about is made up of cell bodies. Myelin is a type of fat in the white part (nerve-heavy area) of the brain. This fat insulates the white matter in the brain and makes the transmission speed between nerve signals fast.

The researchers took MRI scans of the subjects and used a method called fractional anisotropy (FA), which measures organization in the brain by locating the presence of white matter. The teens in the study who had been diagnosed with Internet addition showed lower FA than the typical teens. However, the study only tested 17 young people with IAD and compared them against 16 healthy control subjects.

"Overall, our findings indicate that Internet addiction disorder has abnormal white matter integrity in brain regions involved in emotional generation and processing, executive attention, decision making and cognitive control," write the authors. "The results also suggest that IAD may share psychological and neural mechanisms with other types of substance addiction and impulse control disorders."

Internet addiction is not officially recognized as a disorder because it has yet to be classified in the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM), an encyclopedia of mental and cognitive-related conditions that's a virtual bible for psychologists. But the American Journal of Psychiatry says IAD is common and should be included in the DSM-V, due out May 2013.

People struggling with addiction often exhibit the same types of compulsive and impulsive behaviors. Something becomes an addiction when it interferes with daily activities and the person's ability to enjoy life without that thing — whether drugs, gambling, Internet or some other vice.

Some people might joke they're addicted to their smartphone or computer, but there's a difference between a constructive and enjoyable habit, and a real addiction.

Are you addicted to the Internet? Take the poll below and read these symptoms from the American Journal of Psychiatry's article about Internet addiction:

"All of the variants share the following four components: 1) excessive use, often associated with a loss of sense of time or a neglect of basic drives; 2) withdrawal, including feelings of anger, tension and/or depression when the computer is inaccessible; 3) tolerance, including the need for better computer equipment, more software or more hours of use, and 4) negative repercussions, including arguments, lying, poor achievement, social isolation and fatigue."

Do you think a person can be clinically addicted to the Internet?