A new study from the Department of Energy’s Brookhaven Natural Laboratory released this week suggests that people addicted to certain types of drugs might actually have lower density in crucial parts of their brain.
This and previous studies have shown that cocaine-addicted individuals, relative to non-addicted individuals, have lower gray matter density in frontal parts of the brain – which is important for paying attention and organizing one’s own behavior – and in the hippocampus, a brain region important for learning and memory.
But it doesn’t stop at cocaine. The study revealed that persistent alcohol or cigarette consumption may have a similar effect.
The longer cocaine, alcohol, and cigarettes were abused, the lower gray matter was found in the hippocampus and frontal regions of the brain.

This result means that curtailing drug use may be protective against such brain changes.
The study did not test the effects of other substances. It did, however, clarify that genetic makeup may predispose certain individuals to lose brain matter over

Source: www.huffingtonpost.com 2011/03/13