Beyond the use of MBCT to reduce depressive symptoms, research supports the effectiveness of mindfulness meditation in reducing cravings for individuals with substance abuse issues. Addiction is known to involve interference with the prefrontal cortex, which ordinarily allows for delaying of immediate gratification for longer-term benefits by the limbic and paralimbic brain regions. The nucleus accumbens, together with the ventral tegmental area, constitutes the central link in the reward circuit. The nucleus accumbens is also one of the brain structures that is most closely involved in drug dependency. In an experiment with smokers, mindfulness meditation practiced over a two-week period totaling five hours of meditation decreased smoking by about 60% and reduced their cravings, even for those smokers who had no prior intentions to quit. Neuroimaging among those who practice mindfulness meditation reveals increased activity in the prefrontal cortex.