Scientists have identified a gene involved in the susceptibility to cocaine addiction. The findings could lead to screens for those most likely to become addicted to the drug.
Rainer Spanagel, a professor of psychopharmacology at the Central Institute of Mental Health in Mannheim, Germany, led the work along with other teams in Spain, Brazil and the UK. The research, reported in the US journal Proceedings of the National Academy of Sciences, comprised an animal study in mice followed by a study in humans, and found that addicts were 25 per cent more likely to carry a specific gene mutant than non-users.
For the animal part of the study, mice were genetically altered to have a mutation in a specific gene, the mouse form of a human gene called CaMKIV, which the scientists thought may play a role in addiction. The gene makes a protein that is involved in responses to stimuli in nerve cells in the brain. The behaviour of normal mice was compared to the mice with the defective form of the gene in response to cocaine, and a link to addiction was made.
The scientists then ran human genetic tests on 670 cocaine addicts compared to 700 matched non-users. They found that a variation in the gene that resulted in a defective form of the protein was present in 50 per cent of the addicts compared to only 40 per cent in non-users. They concluded that 'the activity of CaMKIV regulated susceptibility to cocaine in laboratory animals and in humans'.
Spanagel said: 'you can certainly use this as a vulnerability marker for cocaine addiction', and proposed that people found to be susceptible could be given counselling.
There are, however, many environmental factors involved with addiction, and it is thought that other genes are also likely to play a role, further complicating the issue of identifying those susceptible to addiction. More research is required before firm conclusions can be drawn, but scientists hope to develop approaches for treating addiction. Experimental vaccines are now being designed that block the euphoria associated with the drug, with the hope of protecting the people found to be susceptible to cocaine addiction.