"We have to understand that a core feature of addiction is that you know it is going to harm you, potentially even kill you, and nevertheless something has gone wrong with the motivational control and you keep doing it," said Markus Heilig from the Linkoping University in Sweden.
For the study, the team used a mouse model to measure the expression of hundreds of genes in five areas of the brain. The animal study gave very startling insights of human brain and patterns of addiction.
As part of the investigation, the role of reduced GAT-3 levels in rats was examined. These rats initially preferred sweetened water over alcohol . After the reduction, they were again presented with the choice between alcohol and sugar. The findings revealed that 15 per cent of the outbred rats chose alcohol over a high-value reward.
"Decreasing the expression of the transporter had a striking effect on the behaviour of these rats. Animals that had preferred the sweet taste over alcohol reversed their preference and started choosing alcohol," said lead investigator Eric Augier.
The team further examined the GAT-3 levels in brain tissue from deceased humans who had documented alcohol addiction. They were found to have lower levels of the protein than the control individuals.
Scientists are optimistic that the findings may help improve treatment for alcohol dependence.