The addiction to stimulant drugs is a serious issue that confronts modern society. In those so afflicted, it is characterized by a satellite of issues including a behavioral pattern that grows out of control in the pursuit of obtaining and consuming ever-increasing amounts of drugs in spite of the fact that the use of these drugs negatively impacts both the individual's health and his or her social and personal life.
In light of recent evidence, drug addiction has come to be regarded as a, "relapsing brain disorder." In support of this view, marked structural changes in the striatal and pre-frontal brain regions have been reported in individuals with stimulant drug addiction. The pre-frontal area of the brain is ordinarily recruited in the regulation and moderation of behavior. Therefore, any deficit within this region may explain the dependency upon stimulant drugs on account of the fact that these chemicals impact those areas of the brain involved in motivated behavior.
The question naturally arises as to whether addiction itself causes changes in the structure of the brain or the structural anomalies described above precede the addictive behavior and predispose the affected individual to drug taking and its concomitant risky behavior. In support of the latter argument, the structure of the individual brain is an inherited characteristic and drug addiction is known to run in families. If, in fact, drug addictive behavior is an inheritable trait, the changes in brain structure would be regarded as an endophenotype – a trait that is a direct result of a genetic anomaly (genotype) and that is responsible for the overt clinical symptoms (phenotype).
In order to test this hypothesis, Dr. Karen D Ersche and her colleagues from the Behavioral and Clinical Neuroscience Institute and Department of Experimental Psychology and Department of Psychiatry at the University of Cambridge, Cambridge, UK, conducted a study in which, "we compared brain structure and the ability to regulate behavior in 50 biological sibling pairs." As a result of this exhaustive investigation, it was shown that the fronto-striatal regions of the brains showed marked abnormalities in not only addictive individuals but their biological siblings who possessed no apparent symptoms of drug dependency. The demonstration of changes in brain structure in close family members establishes the genetic connection and strongly suggests that such endophenotypic changes predispose the individual to drug addictive behavior.
These findings are of immense importance in not only understanding the nature of drug addiction, but also informing the general public and the legal system on how to best deal with addictive individuals. In addition, further studies designed to discover the underlying genetic abnormalities associated with this condition could provide immeasurable help in finding appropriate therapies for this brain disorder.