Researchers identify a gene for cocaine addiction
NOVEMBER 12, 2008
New research published in the US Journal, Proceedings of the National Academy of Sciences this month reports that scientists have found a gene that increases the likelihood of an addiction to cocaine. Researchers have shown that addicts are more than 25 per cent likely to carry the gene variant than people not using cocaine. This research is collaboration between the Central Institute of Mental Health in Mannheim, Germany, who led the study, the Federal and State Universities of Sao Paulo and the Addiction Biology Group at the Institute of Psychiatry, King’s College London. led by Gunter Schumann, Professor of Addiction Biology.
The research team in Germany linked a version of the CAMK4 gene with cocaine addiction after studying mice that had been genetically modified to alter the gene. One particular breed was affected more strongly by the drug and became addicted quicker than others in the group. Researchers at the Institute of Psychiatry wanted to see if this gene played a role in cocaine addiction in humans and ran genetic tests on 670 cocaine addicts and more than 700 matched non-users from Sao Paulo, Brazil. Looking at variations in the promoter of the gene, the team found one where 50% of cocaine dependent individuals and 40% in controls had an AA genotype.
"If you are a carrier of this gene variant, the likelihood of getting addicted to cocaine is higher," said Prof. Schumann, , who co-authored the research.
Dr Gerome Breen, aother co-author on the study added that "However, the size of the effect of this common variation means it is unlikely to be of use in predictive testing for cocaine addiction."
Genetic factors account for 70 per cent of cocaine addiction, scientists believe, making it as heritable as schizophrenia and other mental health conditions. However, many of the genetic variations involved probably exert their effect via interactions with environmental risk factors. The researchers hope this finding can help point the way towards novel and better treatments for the disorder, although much more work is necessary before this could be achieved. Such developments are needed, particularly in the UK as the European Union’s drug agency analysis has recently put the UK at the top of the list of countries abusing cocaine, with cocaine users outnumbering those anywhere else in Europe.
Please refer to 11 November 2008 edition of PNAS for a full copy of the paper entitled: Loss of the Ca2/calmodulin-dependent protein kinase
type IV in dopaminoceptive neurons enhances behavioral effects of cocaine.