Pornography triggers brain activity in sex addicts similar to the effects that drugs have on the brains of drug addicts, researchers said on Friday — but that doesn't necessarily mean porn is addictive.

Although there are no precise figures, experts believe as many as 1 in 25 adults is affected by compulsive sexual behavior, more commonly known as sex addiction — an obsession with sexual thoughts, feelings or behavior they are unable to control.

Excessive use of pornography is one of the main features of the condition. That can affect personal lives and work, causing distress and feelings of shame, the researchers from Britain's Cambridge University said in a study published in the journal PLOS ONE.