According to study chief Dr. Kenneth S. Kendler, previous studies on the role of genes in illicit drug use were conducted in countries with high rates of drug abuse, namely the United States and Australia.

"This is the first study to show the importance of genetic factors in a culture/country (Norway) with rather low rates of drug problems," explained Kendler, who is from the Medical College of Virginia in Richmond.

"It has been suggested that in such countries, social rather than genetics factors should prove to be most important. Our results do not support that hypothesis," he said.

Kendler's team interviewed and assessed 1,386 Norwegian pairs of young adult twins about their lifetime use of illicit drugs, including marijuana, stimulants, opiates, cocaine, and psychedelics. They report their findings in the journal Psychological Medicine.

The findings overall, Kendler told Reuters Health, provide "rather strong evidence that individuals differ in their risk for drug abuse, that this difference is rather strongly influenced by genetic factors and this pattern of findings occurs in cultures with both low and high rates of drug abuse."

[Continue Reading]