The topic of marijuana addiction is emotionally charged. The two aspects of addiction—withdrawal symptoms unique to marijuana and alterations in the brain’s reward mechanism common to all addictive drugs—must be approached separately. THC’s stimulation of CB1 receptors causes a homeostatic reduction of receptor density, called downregulation. When THC stimulation wanes, the resultant relative lack of receptors leads to a transient deficiency of endocannabinoid activity. Hirnoven found a 20% reduction in endocannabinoid receptors in the cortex of individuals regularly using marijuana requiring 4 weeks of abstinence to be reversed. The effects of cannabinoid deficiency outlined by Budney include withdrawal symptoms of restlessness, anxiety, insomnia, boredom and irritability. Relapse to marijuana use often occurs to abort withdrawal symptoms. The influx of dopamine in the reward center (nucleus accumbens) caused by excessive cannabinoid stimulation is the sine qua non for addiction and leads to a neurologically based increase in the salience of marijuana. Modification of reward mechanisms increases the motivation to use marijuana to the point that cognitive rationality is clouded and denial is produced.