Repeated use of drugs like cocaine and other stimulants often causes powerful addictions that can be difficult to overcome without assistance from rehab facilities. In fact, a new study has found that these drugs actually change the brain's circuitry, which makes recovery following addiction a difficult process.

Researchers from the University of California, Berkeley found that individuals who previously used cocaine show alterations in their brain's chemistry that cause the so-called "reward" neurotransmitter, dopamine, to be released when the recovering addict is exposed to cocaine-associated cues.

Additionally, dopamine is released into areas of the brain that are more malleable and susceptible to persistent changes.

Mu-Ming Poo, who led the investigation, said that the findings help explain why recovering cocaine addicts still feel cravings for the drug after they have gone through withdrawal and remained sober for extended periods of time.

While the study did not mention whether this alteration in brain chemistry can be reversed, experts often say that recovering addicts have a better chance of success with the help of drug rehabilitation.