The genes that make you prone to illegal drug abuse are different from those that cause dependence on legal substances like alcohol and nicotine, a new study has found. And genes that control caffeine addiction are entirely independent.
Researchers at Virginia Commonwealth University who examined the degree to which genetic risk factors for dependence were shared between illicit and the licit drugs, say their findings could help identify genes that lead to drug abuse or dependence (A/D).
The findings of the study appear in the November issue of the Archives of General Psychiatry.
"We wanted to know whether there was a single set of genes that influence risk for A/D on all substances," said Kenneth S. Kendler, lead author of the study.
"Our findings suggested two genetic factors - one which strongly impacted on risk for A/D of illicit drugs, such as cannabis and cocaine, and one that impacted on risk for A/D of licit drugs, including caffeine, nicotine and alcohol. However, these two factors were rather strongly correlated."
Kendler said: "This study also confirmed the strong role that genetic factors play in influencing our vulnerability to drug abuse and dependence."
Heritability - the proportion of individual differences in risk due to genetic differences - was estimated in this study to be more than 70 percent for cocaine, cannabis and nicotine A/D, nearly 60 percent for alcohol A/D, and, interestingly, quite a bit lower - around 35 percent - for caffeine A/D, he said.
A team of 36 medics began a complicated surgery at a super-speciality hospital here Tuesday to separate a two-year-old girl child with eight limbs from her 'parasitic conjoined twin' and enable her to lead a normal life.
A spokesperson of Sparsh Hospital in Narayana health city on the outskirts of Bangalore said the rare surgery on Lakshmi, from Araria in Bihar, began at 8 a.m. and would take about 40 hours to complete.
"It's a delicate surgery involving complicated cutting-edge operation, which is being conducted for about 40 hours non-stop. Though Lakshmi is a pair of conjoined twins, only one of them has a head. Two pairs of arms and legs have formed at either end of the two adjoining torsos, creating eight limbs, which she has been able to move and control," the official said.