Even people who consider themselves to be casual cigarette smokers may be addicted, according to current diagnostic criteria. Researchers at Penn State College of Medicine and Duke University found that many light smokers who smoke one to four cigarettes per day or fewer meet the criteria for nicotine addiction and should therefore be considered for treatment. The researchers examined an existing data set from the National Institutes of Health, including more than 6,700 smokers who had been fully assessed to find out if they met the DSM-5 criteria for tobacco use disorder. They found that 85% of the daily cigarette smokers have addicted to some extent either mild, moderate or severe addiction.